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The effects of atmospheric ionization on insects measured with a stationary flight apparatus Hildebrandt, Jacob 1960

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THE EFFECTS OF ATMOSPHERIC IONIZATION ON INSECTS MEASURED WITH A STATIONARY FLIGHT APPARATUS by JACOB HILDEBRANDT B.A., University of B r i t i s h Columbia, 1957  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n the Department of PHYSICS  We accept this thesis as conforming to the required standard  THE UNIVERSITY OF BRITISH COLUMBIA October, I960:  In presenting the  this  r e q u i r e m e n t s f o r an  thesis in partial advanced degree a t  of B r i t i s h Columbia, I agree that it  freely  agree that for  available  the  f o r r e f e r e n c e and  permission f o r extensive  s c h o l a r l y p u r p o s e s may  D e p a r t m e n t o r by  be  gain  s h a l l not  be  a l l o w e d w i t h o u t my  The U n i v e r s i t y o f B r i t i s h V a n c o u v e r $, C a n a d a .  shall  study.  I  Columbia,  the  of  University  copying of  his representatives.  copying or p u b l i c a t i o n of t h i s  the  Library  g r a n t e d by  that  fulfilment  make  further this  Head o f  thesis my  I t i s understood  thesis for written  financial  permission.  ABSTRACT In recent years a* number of publications have shown a renewed interest in the possible effects of atmospheric e l e c t r i c i t y on bio^ l o g i c a l systems.  The work here presented i s an attempt to measure  the changes i n the behaviour, or the power output, of certain insects; during stationary f l i g h t i n a unipolar atmosphere.  Since several  published references indicate the existence of a "weather sense" i n insects, which has been attributed to s e n s i t i v i t y to atmospheric space charge fluctuations, various species of f l i e s were chosen for this study. Various studies have been carried out on insect f l i g h t endurance with f l i g h t m i l l s .  For this work a new type of closed  insect flight, apparatus has been developed, i n which environmental conditions can be altered, and the p u l l and wing beat frequency of the f l y under test recorded simultaneously.. Insects were attached to a mechano-electrical transducer either d i r e c t l y or i n d i r e c t l y .  The transducer output was resolved  into an AC component, whose frequency corresponds to the wing beat frequency, and a DC component whose magnitude corresponds to the force exerted by the insect i n f l i g h t .  Both components were traced on graph-  i c a l recorders. In a modified apparatus two transducers were used for measuring the p u l l and wing beat frequency independently. Even under identical physical conditions insects were found to behave i n an erratic manner, so that possible small effects due to variations of the ion concentration were d i f f i c u l t to establish..  iii  The spiracles of some f l i e s were dilated by increasing the ambient CO^ concentration up to 15$ causing various changes i n the f l i g h t patterns without rendering them more regular. From a s t a t i s t i c a l analysis of the energies produced, some evidence can be obtained that individuals of Muscina stabulans and L u c i l i a sericata under a negative ionization excess display greater a c t i v i t y than those under normal conditions or under positive ion excess.  More tests w i l l be necessary to substantiate the results. The use of the apparatus as an entomological olfactometer  or for the test of other insect responses i s suggested; several insect repellents were tested on the same apparatus.  iv  TABLE OF CONTENTS  1.  INVESTIGATIONS  INTO THE BIOLOGICAL  A.  General remarks  B.  Atmospheric  EFFECTS OF AIR  IONIZATION 1  ionization. .  .  ( i ) A i r i o n s and c o n d u c t i v i t y measurements  2  ( i i ) Production of a i r ions  4:  ( i i i ) Physiological studies (iv)  Mechanism o f i o n a c t i o n  C.  Insect  D.  Method o f i n v e s t i g a t i o n  8  studies  (i) Flight  8  9  mills  ( i i ) Stationary  2.  5>  flight  apparatus  10  EXPERIMENTAL DEVELOPMENT OF A STATIONARY FLIGHT  A.  Preliminary  B.  Transducer  s t u d i e s on i o n s p r o d u c e d operated s t a t i o n a r y f l i g h t  ( i ) Mechano-electronic  (j.'O.  (iv)  by a t r i t i u m apparatus  source  12 . . . . . . . 1 2 - '  Feeding Flight  13 stimulation  Transducer  ( v i i ) Wing b e a t  (ix)  .15  calibration  . . . .  16  f r e q u e n c y d e t e r m i n a t i o n and r e c o r d i n g .  ( v i i i ) Time o f f l i g h t Pull recording  :  . . . . . . . . . 1 4  (v) T o r s i o n w i r e (vi)  .11  . . . . .  transducer  . ( i i ) c l n s e c t i mounting  (iii)  APPARATUS  integration  . . 16  . . . . . 1 7 . . . 1 8  V  C.  A p p l i c a t i o n o f the s t a t i o n a r y f l i g h t apparatus ( i ) Experiments i n i o n i z e d a i r (a) Ion Sources  . . . • • . • • • 1 9  (b.) Grounding the i n s e c t  . . . . . . 1 9  (c) Experimental, c o n t r o l s  20  ( i i ) A d d i t i o n o f carbon d i o x i d e to i o n i z e d a i r  21  ( i i i ) Use of i n s e c t r e p e l l e n t s D.  3.  22  Insect rearing ,  22  RESULTS OF AIR-IONIZATION STUDIES A.  Observations on i n s e c t f l i g h t  24  B.  Insect f l i g h t i n an i o n i z e d atmosphere. . . . ( i ) Description of f l i g h t records.  \  . . . . . . . . . . . 2 6  ( i i ) Duration of f l i g h t  .27  ( i i i ) Power and energy o f i n s e c t s i n f l i g h t  27  ( i v ) Forward p u l l and speed of i n s e c t s i n f l i g h t (• ' :(v)'jEffectaof(;cafbonJ.d'ioxide^and'insectlfepeitlents C.  F i n a l Discussion  . . . . .  30 ...  31 32  APPENDICES A,  An estimate o f the mean distance d i f f u s e along a t r a c h e o l e  B.  through which i o n s  of radius  IOJA.  .  34  Improved e x p e r i m e n t a l arrangement f o r f u r t h e r i n v e s t i g a t i o n 37  BIBLIOGRAPHY  39 i  LIST OF  ILLUSTRATIONS, TABLES, AND  Fig.  1  Determination  Fig.  2:  Ion c u r r e n t d e n s i t y f r o m a 50 m i l l i c u r i e as a f u n c t i o n o f d i s t a n c e and p o t e n t i a l  Fig.  3  of i o n current density  Method f o r m e a s u r i n g e f f e c t s o u r c e and c o l l e c t o r p r o b e by  44' tritium  source? 44  of metal g r i d s  between 45  Fig.  4  Currents produced  Fig.  5  D i a g r a m o f RCA  Fig.  6  Basic bridge c i r c u i t  Fig.  11  Method o f a t t a c h i n g i n s e c t  Fig.  8  View o f t o r s i o n w i r e m o u n t i n g  Fig.  9  Method o f c a l i b r a t i n g  t h e arrangement  5734 t r a n s d u c e r and  shown i n F i g . 3 . . .  extension , . . . . .  shown i n P l a t e  displacement  and  3  output  48 of  the  force  49  Calibration  Fig.11  Method o f o b t a i n i n g c o n s t a n t f l o w o f COg  Fig.12.  COg  curves f o r transducer  ..49 50  i n t h e wind t u n n e l as a f u n c t i o n  p r e s s u r e a t the o r i f i c e  o f gas  50  l e v e l s were sampled  51  P o i n t s i n the wind t u n n e l a t w h i c h COg  Fig.14  R a t e o f i n c r e a s e o f CO,, a t p o i n t s shown i n F i g . 13  Fig.15  Sample f o r w a r d the  stationary  r e c o r d i n g o b t a i n e d f r o m an  flight  Wing b e a t  Fig.17  T r a n s f o r m a t i o n o f V o l t a g e v e r s u s Time g r a p h s  Fig.19 Fig.20  51  insect  apparatus  Fig.16  Fig.18  frequency  . . . .  . . . . . . . . .  Fig.13  in  47  . . . . . . 4 8  F i g . 10  force  52  r e c o r d accompanying F i g . 15.  . . . . .  53  shown i n  F i g . 15 i n t o V o l t a g e 3/2 v e r s u s Time p l o t s . . . . . . . . P u l l changes due t o t h e p r e s e n c e o f two commercial repellents . B l o c k d i a g r a m o f f l i g h t a p p a r a t u s and. a u t o m a t i c r e c o r d i n g system Detailed  schematic  diagram  46 47  f o r transducer  transducer f o r a given applied  levels  PLATES  . . . . .  54 54 55  ..56  vii  Table 1  Tabulations of. duration of insect f l i g h t  57  Table 2.  Energies of f l i e s measured i n the f l i g h t apparatus under normal conditions and under ionization. . . . . .  59  Table 5.  Summary of results of ionization study.  61  Plate 1  Experimental arrangement.  62!  Plate 2  Flight apparatus and graphical recorders. . . . . . . .  63  Plate 3  Detail of f l i g h t apparatus  64  ...  viii  ACKNOWLEDGEMENT This work was carried out with the assistance of a National Research Council of Canada Bursary and Studentship  to the writer during  the period September, 1958, to May, I960, and a National Research Council of Canada Research Grant to Dr. Otto Bluh» Thanks are expressed to the National Research Council of Canada for their f i n a n c i a l support, and to Dr. 0. Bluh f o r the suggestion of the research topic and for placing his research funds at my disposal. I am.grateful  to Mr. G. J . Spencer, Professor Emeritus of  the Zoology Department, f o r frequent advice regarding  entomological  problems, and to Mr. Earl Price, of the Physics Department, for his help i n technical matters during the construction of the apparatus.  1  1.  INVESTIGATION INTO THE BIOLOGICAL EFFECTS OF AIR-IONIZATION  A,. General remarks Throughout history claims have been advanced for possible weather effects on l i v i n g organisms.  It was recognized that physiolog-  i c a l and even psychological states of man were affected by certain atmospheric conditions, e.g., thunderstorms, or wind currents variously known as Fohn, Mistral, Solano, Chinook, etc.  Various- efforts have  been made to isolate the known physical variables, such as temperature, pressure, humidity, atmospheric pollutants, etc., and to measure their effects.  In the present century a considerable number of investiga-  tions have centred around such additional geophysical variables as atmospheric e l e c t r i c i t y and radioactivity, geomagnetism, sunspots, cosmic radiation, gravitational f i e l d s , and ozone concentration. These studies indicated that atmospheric ionization i s one of the e l e c t r i c a l factors i n our environment having certain specific physiological effects, and, to some extent affecting man's general state of ^ e l l being'.  The mechanism by which extremely small numbers of unipolar  charges can influence an organism has not, so f a r , been elucidated and experiments are s t i l l under way i n several countries i n order to c l a r i f y the matter.  Considerable s c i e n t i f i c interest has been attached to the f i e l d of biometeorology, or the study of the influence of climate, weather, altitude, etc., on animals and plants and i n particular on  2  man's health.  This border-field of medicine and meteorology has  produced a certain amount of inconclusive and even conflicting publications.  In the past decade attempts have been made to review c r i t i c a l l y  a l l previous work, to isolate the many variables i n weather which affect l i v i n g organisms, and to make controlled quantitative laboratory experiments.  By isolating the variables one may,  however, be eliminating  the natural conditions which might consist of a combination of factors. Interest i n the therapeutic uses of ions has stimulated successful research into c l i n i c a l applications, for example, i n the r e l i e f of air-borne a l l e r g i e s , asthma, and high blood pressure.  B.  Atmospheric ionization  (i)  A i r ions and conductivity measurements  Coulomb had noticed the e l e c t r i c conductivity of a i r in 1795 > but i t was not u n t i l 1899  that Elster and Geitel discovered the  existence of a i r ions, i . e . , gaseous particles of molecular size i n the atmosphere, carrying positive or negative charges.  The ionizing  process almost always occurs by the removal from Og or Ng of one electron which then may become attached to neutral Og forming 0~, or much less frequently, recombine with the positive ion.  None of the  electrons become attached to Ng and Ng, ions are not observed (Martin 1954).  Thus the ultimate result of ionization i s the production of  negative molecular  ions of oxygen, and positive molecular  nitrogen and oxygen, with the  predominating.  ions of  Ion clusters are formed  3 when dipolar water molecules and perhaps also polarized oxygen molecules attach themselves to the ions, or when the ions become bound to atmospheric impurities. Free a i r ions have been c l a s s i f i e d on the basis of their size and mobility into three categories: small, large, and intermediate. The small ions have mobilities (v  v= velocity,  ) between 1 and 2 cm/sec. per volt/cm.,  £"= f i e l d strength).  It has generally been found  that negative ions have s l i g h t l y greater mobilities than positive ions (Chalmers 1957, p. 55)» although the values depend on humidity, temperature, pressure, age, the presence of 0^, or of other substances, etc. The small ion i s thought  to consist of roughly 4 to 12; Og, or HgO molecules:  clustered around the charged p a r t i c l e . The much larger Langevin ions (1905) have mobilities i n the order of l/500 that of the small ions and are probably charged atmospheric pollution particles or condensation nuclei (evaporated sea s a l t , dust, smoke, acid, etc.) The third or intermediate group discovered by Pollack (1915) with/-between 0.1 and 0.01 CGS i s believed to consist of HgSO^ particles comprising some 2000 molecules each (Chalmers, p. 57). Since 1905 mobilities and also ionic concentrations have been measured by the c y l i n d r i c a l condenser method of Gerdien p. 128).  (Chalmers,  A later version with p a r a l l e l plates using essentially the  same principle has been described (Hicks and Beckett, 1957/), while on a different principle, Montel (l939» 1944, 1956) u t i l i z e d the transit time between two AC grids*  4  A very ion  (Krueger,  target, per  equation area  and convenient  Hicks, Beckett unit area  1958).-  The number N o f i o n s  o f the probe.  of a i r ions  p r i n c i p a l n a t u r a l agents g i v i n g r i s e  p h e r e above l a n d a r e ( F r e y 1 9 5 6 ) : giving  rise  t o i o n s i n t h e atmos-  ( l ) the r a d i o a c t i v i t y  t o 4.9 i o n p a i r s p e r c c p e r s e c ;  of free a i r  (2?) t h e r a d i o a c t i v i t y o f  e a r t h : 3.1 i o n p a i r s / e c / s e c ; and (3} s p a c e r a d i a t i o n : 1.5 i o n  pairs/cc/sec;  that  an a v e r a g e ambient The  latter  ion  pairs/cc.  i s , a t o t a l o f 9.5 i o n p a i r s / c c / s e c r e s u l t i n g i n i o nconcentration  f i g u r e may v a r y  o f approximately  suggested, e f f o r t s desired proportions  700 i o n p a i r s / c c .  w i t h w e a t h e r c o n d i t i o n s f r o m 40 t o 80,000  Ever since the p o s s i b l e therapeutic value  o f a i r i o n s was  have b e e n made t o p r o d u c e them a r t i f i c i a l l y i n f o r c o n t r o l l e d experiments without  on t h e v i c i s s i t u d e s  o f the weather.  Dessauer  and  (19.39) p r o d u c e d i o n s b y c o r o n a d i s c h a r g e s  points with high voltages  inert  (1931) c h a r g e d  particles  Tchijevsky  of pharmacologically  having to  submicroscopic  MgO i n a f l a m e ,  g e n e r a t e d b y an e l e c t r o s t a t i c  A l t h o u g h i t was f o u n d t h a t d e l e t e r i o u s n i t r o g e n o x i d e s any  striking  N=l/qA, where I = c u r r e n t , qi = e l e c t r o n i c c h a r g e , a n d A  The  rely  i o n current  and p e r u n i t time, i s determined from the  ( i i ) Production  the  means o f o b t a i n i n g a measure o f  d e n s i t i e s employs a m i c r o m i c r o a m m e t e r a n d t h e B e c k e t t  probe the  simple  high voltage  discharge,  this  type  of ion generator,  from  sharp  machine. and 0^ accompany now m a n u f a c t u r e d  5 by the Philco Corporation i s being successfully used i n allergy treatment (Kornblueh, Piersol, and Speicher 1956, Locke I960). X-rays and u l t r a v i o l e t rays have been known for some time to produce a "clean" ionization, but the equipment was elaborate and costly, while the efficiency of ion production was r e l a t i v e l y low.  The  Westinghouse "Sterilamp" (Knowles and Reuter 1940;) was expected to overcome some of the d i f f i c u l t i e s encountered  i n UWionization.  Apparently i t i s s t i l l under development (Science News Letter, 75(12), p. 185, 21 Mar. 1959). In 1952; the Wesix E l e c t r i c Heater Company instituted a research project to study and design radioactive sources.  Polonium: 210, emitting  short range alphafe was replaced i n 1956 by the longer-lived tritium, adsorbed on titanium.  The tritium f o i l i s i n the centre of a plastic  holder; i t emits soft beta rays (l5 KEV), which ionize the surrounding air.  The plus and minus ions may be separated e l e c t r o s t a t i c a l l y .  This type of ion generator i s now most frequently employed, and has been used i n the present investigation.*  ( i i i ) Physiological studies; The literature on ionized a i r can be traced back to 1903 when Sokoloff f i r s t pointed towards natural ionization as a biological factor.  The favourable effects of negative ions on blood pressure,  * Thanks are expressed to Mr. Wesley W. Hicks, President of the Wesix E l e c t r i c Heater Company, San Fransisco, who provided us with three ion sources.  6  respiration, and general fatigue reported by Dessauer ( l 9 3 l ) , a f t e r 10 ?  years of study, have generally been supported by subsequent investigators (Yaglou et a l . 1933,  Okada 1938,  etc.)..  at least 20 papers between 193.4. and 1941  The Russian Tchijevsky  published  i n which he attributed remarkable  curative powers and l i f e - s u s t a i n i n g q u a l i t i e s to ions.. After 1946 earlier statements.  a trend developed to discount almost a l l of the Awareness of the lack of uniform experimental  conditions, and of the production of ozone and nitrous oxides i n the e l e c t r i c a l discharge methods of ion generation are responsible for the lack of f a i t h sometimes found i n discussing the  subject..  For many years people have t r i e d to determine what weatherfactors can be correlated with the observed periodic changes during illnesses, of accident rates, death rates, b i r t h rates, moods, etc. As such changes occurred indoors as well as i n the open, a i r e l e c t r i c a l factors were examined which penetrate buildings without  appreciable  losses, and when a i r ion densities measured indoors were found to follow closely those measured outdoors (Israel 195l), this discovery supported the theory that ionization could be one of the factors involved (Frey 1951,  1952,  Michalowicz 1958,  1955,  Gutmann 1957i von Deschwanden and M i l l e r  Dubos; 1959,  to mention but a few).  such investigations are i n general inconclusive.  1952,  The results of  The d i f f i c u l t i e s and  dangers of making hasty correlations with single meteorological  factors  have been emphasized by Israel (l95l))» Berg (19.55)'., Hartweger (1956), and Buettner (1957). At the present time most investigators are using  artificial  climates under laboratory conditions, i s o l a t i n g one variable at a time.  7 The main successes have been achieved in experiments on man and certain mammals.  The results to date are quite extensive and only a few of  the major ones can. here be mentioned, Krueger and his associates have been studying the effects of gaseous a i r ions on the c i l i a r y rates of the mammalian trachea (Krueger and Smith 1957,  1958,  1959).  Their conclusion i s that 0~  ions accelerate the rate, while CO^ ions are responsible for the adverse effects such as reduced c i l i a r y a c t i v i t y , contracture of tracheal smooth muscle, pronounced mucosal ischemia, and enhanced vulnerability to trauma due to exaggerated l a b i l i t y of the mucosal vessels (Krueger,  Hildebrand, and Meyers 1959). However, Schorer (1952), after more than ten years study, reported that whenever the number of negative ions exceeded the positive ions, the feeling of well-being was  disturbed.  Kornblueh has attempted to resolve some of the discrepancies (Licke I960); by postulating that positive charges may be beneficial only for heart ailments  (in those 60$ of the population who are not  entirely immune to ions), whereas negative charges are generally to be preferred.  c  Studies have also been made relating ion a c t i v i t y to glandular a c t i v i t y (Nielson and Harper 1954), growth (Danforth 1952-, Worden and Thompson 1956), pollinosis (Kornblueh and G r i f f i n 1955), tumor., regression (Eddy et a l . 195l)> ulcers (Cupcea et a l . 1959)» rheumatism (Tchijevsky 1940:, Verdu 1955), and other physiological functions and diseases*  8. (iv) Mechanism of ion action Rohrer (1952) concluded from studies on dissolved protein that positive ions could cause the stimulating action of vagotonal regulation by electron withdrawal, or oxidation.  Krueger and Smith  (195-9.X offer an explanation on an enzymatic basis for the acceleration in c i l i a r y rate by negative ions and the concomitant beneficial effects to the respiratory system through the observation that negative ions increase the rate of reduction of cytochrome oxidase* Cupcea, Deleanu, and F r i t s (1959) summarize three possible mechanisms thus far proposed (mainly by East-European researchers): (l); a pulmo-gastric or tracheo-gastric reflex, (2.) a humoral pathway, through change i n c o l l o i d s t a b i l i t y of serum protein, or (3) by charges taken up which exert direct effects on the brain stem.  It i s of course  also possible that a combination of these pathways may be operating. Discrepancies s t i l l persist i n the l i t e r a t u r e , even though measuring techniques and ion control have greatly improved.  The absence  of any well-founded theory about the physico-chemical mechanism of ion action makes i t s e l f f e l t i n the continuing controversial nature of statement on the subject*  C. Insect Studies  Entomologists have observed behavioral changes among certain insects i n association with storm a c t i v i t y ; f o r example Uvarov (l93l) refers to a book by Marchal (1912) i n which the statement i s found that  9 i n s e c t s a r e more a c t i v e observed  just  prior  an i n c r e a s e d i r r i t a b i l i t y  honey b e e s i n f l u c t u a t i n g  fields  ( q u o t e d by W e l l i n g t o n , 1957)..  to thunderstorms. and  an a l t e r e d  P r a e n k e l and on  of  flight  activity,  statements,  pull  of a i r i o n concentration. and w i n g b e a t  thunderstorms Andrewartha  i t seemed  a l a b o r a t o r y study o f the m e t a b o l i c  i n s e c t s as a f u n c t i o n  of insect  Gunn ( l 9 4 0 ) and  among  insects.  I n view o f t h e s e o b s e r v a t i o n s and to undertake  (1954)  f o o d uptake  corresponding to those of  (1954) a l s o m e n t i o n w e a t h e r e f f e c t s  profitable  Schua  frequency  activity  As m a n i f e s t a t i o n  during  stationary  were m e a s u r e d .  D.  Method o f  (i)  Investigation  Flight  Metabolic  mills  s t u d i e s concerned  with f l i g h t  e n d u r a n c e and  c o n s u m p t i o n have b e e n made w i t h v a r i o u s forms o f r o u n d a b o u t s the i n s e c t t o an arm  i n which  i s c o n s t r a i n e d to f l y i n a c i r c u l a r p a t h by b e i n g a t t a c h e d free  to r o t a t e  i n a horizontal plane.  I n t h i s way  Krogh  W e i s - F o g h (1952:)' f l e w a number o f l o c u s t s s i m u l t a n e o u s l y * and (1953) made e x t e n s i v e s t u d i e s on A  similar  used  energy  flight-mill  was  built  the b i t i n g  flies  and  Hocking  of NorthemSanada.  on s u g g e s t i o n o f D r .  Otto Bluh  and  by a r e s e a r c h g r o u p i n the F e d e r a l E n t o m o l o g i c a l L a b o r a t o r y a t  Kamloops, B.C., t h e Og  as  e a r l y as 1952^ ( u n p u b l i s h e d ) .  consumption o f l o c u s t s  the sensory h a i r patches (Weis-Fogh 1949).  on  Krogh  i n stationary flight  (l95l);  while  determined  stimulating  t h e f r o n s and v e r t e x w i t h an a i r s t r e a m  10 (ii.)' Stationary f l i g h t apparatus Tor our purposes f l i g h t - m i l l s or roundabouts were thought unsuitable since observations and measurements are much more readily made on a stationary insect, and furthermore, the large volume of a i r required could not be kept uniformly ionized at a high ion density. That stationary f l i g h t i n an a i r stream was i n most respects equivalent to free f l i g h t was shown by Hollick (1940), provided the velocity of the a i r stream was equal to the speed of f l i g h t of the insect. It was accordingly decided to attach the specimen under test to a sensitive mechano-electrical obtain an instantaneous  transducer i n a wind tunnel to  measure of the p u l l exerted by the insect.  Of the five methods of obtaining the wing beat frequency described by Hocking (1953), the stroboscopic technique was by far the simplest, although, as w i l l be described later, i t proved inadequate for our purposes.  Both parameters were found to be subject to f a i r l y rapid  fluctuations so i t was essential that they be recorded for future comparative studies.  simultaneously  11  2.  A.  EXPERIMENTAL DEVELOPMENT OF  Preliminary  Unipolar by means o f t h e  s t u d i e s on  a r r a n g e m e n t shown i n F i g . 1.  a grounded guard r i n g the  vicinity  equipped w i t h  i o n s p r o d u c e d by  a tritium  source  i o n d e n s i t y measurements were made i n t h e  c o n s i s t e d of a c i r c u l a r  in  A STATIONARY FLIGHT APPARATUS  brass  The  d i s c of r a d i u s  1.3  to reduce d i s t o r t i o n of  o f the  probe.  a decade s h u n t  collector cm  the  probe  surrounded  by  electrostatic  A K e i t h l e y Model 200 enabled current  laboratory  field  Electrometer  measurements down t o  -13 a p p r o x i m a t e l y 10:  amp.  The  a c c e l e r a t i n g p o t e n t i a l and Wire g r i d s w i t h as  shown i n F i g . 3.  e l e m e n t s and  the  By  dependence o f  on  electrode  a 7 mm  varying  distance  the  current  separation  relative  DC  i n the  ion  p o t e n t i a l s of  the  between e l e m e n t s i t was  p o s s i b l e to  a s e r i e s o f c u r v e s s i m i l a r t o vacuum tube c h a r a c t e r i s t i c s , grid  and  collector I t was  of the as  various  currents, voltages,  assumed t h a t  o f the  o b s e r v e d i t c o u l d be approximately equal  give  that rise  the  ion-current  concluded  to the  characteristics.  m o b i l i t i e s , i . e . , that  concentration  o f the  relating ( F i g . 4.).  would appear Since  none were  same p o l a r i t y  t h e y were a l l l i g h t  o f p o l l u t a n t s i n the  t o heavy i o n s , was  stream  d i f f e r e n c e s i n the m o b i l i t i e s  ion current  that a l l ions  2.  obtain  i n t e r e l e c t r o d e spacing  appreciable  a i r ions g i v i n g r i s e  irregularities  and  any  and  on  i s shown i n F i g .  mesh were t h e n p l a c e d the  density  negligibly small.  have  ions  l a b o r a t o r y , which  may  12  Bi  Transducer operated stationary f l i g h t apparatus:  ( i ) Mechano-electronic transducer For converting a small mechanical force or displacement into an e l e c t r i c a l impulse (cf. for literature Lion 1959) a transducer tube, type RCA 5734, was selected.  As i l l u s t r a t e d i n F i g . 5, i t i s essentially  a triode with the grid and cathode assembly held i n a fixed position, while the anode, supported by a rod, i s capable of angular displacement through the centre of a thin f l e x i b l e metal diaphragm, thus altering the plate current. An extension of the l / 8 " plate-pin by means of a thin glass rod of 4" or 5" length increased the s e n s i t i v i t y enough to enable a blowfly, exerting a force of 30 mg for example, to produce a voltage change of approximately 1 volt i n the bridge c i r c u i t shown in F i g . 6. To minimize d r i f t , care must be taken to provide constant voltages for both the filament and plate.  (Thus one must allow for  a time of about 8 hours after charging a lead storage c e l l to permit the voltage to become stable.)  It was found that the variable balancing  potentiometer should be small relative to the fixed resistances so that i r r e g u l a r i t i e s at the s l i d i n g contact w i l l not appreciably affect the stable balance (Fig. 6).  The output from point A may then be amplified  for display or recording.  ( i i ) Insect mounting The specimen may be immobilized for mounting by ether, etc., but for insects anaesthesia with COg has been found most convenient.  133  A short exposure for 1 min. i s usually sufficient for 30 sec anaesthesia during which time the insect may be attached to i t s mounting f o i l (Fig.  7). It was found that a narrow strip of aluminum takes up most  of the unwanted complex vibrations set up by the wing motion, leaving -  only a sine wave for each wing beat.  Presumably i n order for the c l i c k  mechanism to function, the mesonotum moves dorso-ventrally while the wings take up bistable positions (Pringle 1958).  The thin f o i l thus  serves also to allow almost free mesonotal movement in the v e r t i c a l plane. For attaching the insects to the f o i l Hocking has suggested a mixture of beeswax and resin, although beeswax alone seems to serve the purpose quite well.  A droplet of wax i s melted onto the t i p of  the f o i l with a 5 watt nichrome wire heater and quickly applied to the middle of the mesonotum i n the region devoid of macrochaetae anterior to the scutoscutellar suture.  (Care i s taken not to seal  the suture because the scutellar sclerite must remain free to articulate during wing movements.) The droplet which s o l i d i f i e s immediately on contact i s kept as small as possible consistent with firm attachment.  ( i i i ) Feeding Hocking's study revealed that many adult insects when flown to exhaustion require only carbohydrates and a brief rest while feeding before continuing again in prolonged f l i g h t .  Consequently before each  t e s t - f l i g h t i t i s necessary only to feed the insect a few mg of 20-25$ sugar solution.  For precise metabolic studies Hocking coated the bore  of his micropipettes with wax: to prevent adhesion of sugar solution, and then recalibrated them.  14  F o r our p u r p o s e s i t was an  (l.0A= 0.001  o r d i n a r y 1Q;X  pipette, rubber  controlling  tubing.  tapered  the  stimulus  but  more t h a n rotating of  a few  flight,  even t h e r e w i t h  areas,  apparent haustion.  tarsi,  ( K r o g h and  only L u c i l i a  an  on  test  turned  reason,  the  stops  Once a t r e s t  the  found  to  be for  difficulty  inducing  Aedes communis t o f l y . )  s e r i c a t a and  front  o f the  and  Phormia  s p e c i e s used  f l i e s flew without  on u n t i l  the m a j o r i t y stopped  i s suf-  campus, g a r d e n s , Muscina  t h e y were  stabulans stimulated  insect.  e x p e d i e n t , w h i c h p r o v e d s u c c e s s f u l on  Weis-Fogh 195l)  effect  a few  time t h e a i r j e t was  solution.  the a d d i t i o n a l s t i m u l i  to f l y f o r lengthy p e r i o d s , provided  Although  small  so s e r i o u s i n the  the m o v i n g b a c k g r o u n d H o c k i n g had  little  with  the  i n most c a s e s  the s p e c i e s a v a i l a b l e a r o u n d the u n i v e r s i t y  apparently  to  contact  T h i s was  ( T h i s p r o b l e m i s not  a u x i l i a r y a i r j e t d i r e c t e d at the  reserves,  diluting  of t a r s a l  movements.  to m a i n t a i n  although  Removing t h e  had  flight  sufficient  seconds.  induced  Schistocerca  cell  w i t h d r e w t h e measured q u a n t i t y o f  u s u a l l y state that loss  nearby a g r i c u l t u r a l  by an  specimen  s u c t i o n through a length of  m e l l i f e r a , D r o s o p h i l a m e l a n o g a s t e r , and  c o u l d be  the  stimulation  flight-mills,  Of and  f l o w by o r a l  to i n i t i a t e  i t i s not  a i r f l o w and  Apis  c c ) haemocytometer r e d  t i p o f the p i p e t t e and  References  true,  to f e e d  Most s p e c i m e n s r e a d i l y a p p l i e d the p r o b o s c i s  (iv)' F l i g h t  ficient  sufficient  their  they  had  flight  becoming more f r e q u e n t  1959),  here.  i n t e r r u p t i o n from  depleted  after  i n the a i r s t r e a m , an  (Friedman  their  10-20 as  the  the  energy  minutes f o r  no  Insect neared  external stimulus  such  ex-  15 as bodily contact, quickly bringing an object nearby, a loud noise, or shutting off the a i r stream would be required to r e i n i t i a t e f l i g h t * By using the amplified output of the transducer to operate a shutter in the a i r stream i t was possible to obtain f l i g h t s to exhaustion  within  a period of about one hour without further assistance from the operator. Hocking (1953) describes how  his f l i e s alighted on a launching  pad to rest for brief periods and.then once again resumed f l i g h t .  A  landing s t r i p in the form of a rotating r o l l e r was placed below an insect'; in the stationary m i l l .  The f l y was expected to resume f l i g h t  each time i t tried to land and found no firm footing.  A 5 / 8 " OD rubber  hose served as a cylinder, mounted on a horizontal axle belt-driven by a.small reversible e l e c t r i c motor, while the insect was held about 1/8"  from the cylinder surface.  When the r o l l e r was put into motion,  the insect began to f l y immediately, but very soon tried to land.  After  a few thwarted attempts i t would stop flying with i t s legs drawn up away from the r o l l e r . constant  Apparently  the a i r stream i s required as a  stimulus.  (v) Torsion wire To f a c i l i t a t e insect mounting and calibration of the DC amplifier, and for wider v e r s a t i l i t y , the direct mounting (Fig. 5 and Fig. 7 ) was replaced by the torsion wire arrangement shown i n F i g . 8 and i l l u s t r a t e d in the plates.  Strains on the transducer produced while  attaching the f o i l to the lever system were prevented by disconnecting at point B of F i g . 8 .  The effective length of the extension to the  transducer i l l u s t r a t e d i n the figure was 10/3 x 5, or 16.5  cm.  By  16 adjusting the position of point C the mechanical advantage may be altered to suit the size and strength of the insect.  (vi); Transducer calibration The characteristics of the 5734 were checked for l i n e a r i t y by applying a force horizontally to the extension rod (Fig. 9), and measuring the output voltage with VTVM and the displacement on the micrometer scale of a microscope.  The results are shown i n Fig. 10.  Since a l l later experimental measurements were i n the 0 to 2 volt range, i t i s seen that i n this interval both output and displacement are directly proportional to applied force.  ( v i i ) Wing beat frequency determination and recording The frequency of the wing beats was at f i r s t determined by the standard stroboscopic method at fixed time intervals of 20 sec and then plotted graphically.  Because of the unpredictable variation i n  frequency i t soon became apparent that a more rapid means of recording would be required i f the test were to have any v a l i d i t y . By trying a number of different glass extensions to the transducer i t was possible to select a size and weight such that the resonant frequency of the rod (or a multiple thereof) was i n the neighbourhood of the observed wing beat frequency.  A f l y i n g insect then  developed an AC voltage of:''0^05 volt or greater at the transducer, s u f f i c i e n t l y large to be displayed on an oscilloscope.  By comparing  the sine wave from the transducer with the signal from an audio o s c i l l a t o r by means of the Tektronix Dual Trace Unit 53C* one could measure the  17  frequency  continuously.  potentiometer  was  audio o s c i l l a t o r  To  o b t a i n the r e s u l t s  i n g r a p h i c a l form,  mounted c o a x i a l l y w i t h t h e f r e q u e n c y i n the c i r c u i t  shown i n F i g . 19 and  ,  a  c o n t r o l o f the  ;  the o u t p u t d i s p l a y e d  on an E s t e r l i n e - A n g u s r e c o r d e r .  ( v i i i ) Time o f f l i g h t  I t was or decrease on  their  total For  thought  that  the a c t i v i t y  time  This effect  t h e p u l l and wing b e a t  flying  time  o f i o n s m i g h t be  frequency  f u e l w o u l d be  thus might  number o f s t o p s was  s h o u l d t h e n be r e f l e c t e d  pull  frequency.  insect  Triggering  on AC  Mode o f t h e T e k t r o n i x 531  o f them f e l l  Thus a s i g n a l a p p e a r e d  l o n g as the i n s e c t  t o a c t u a t e a DC  was  flying.  also  obtained.  rates.  the  to note  the  clock,  With the  Slow, t h e T r i g g e r i n g  so a d j u s t e d t h a t b o t h t r a c e s f r o m  d i s a p p e a r e d whenever one  total  close  t o o p e r a t e an e l e c t r i c  time was  as  The  c h e c k on a c t i v i t y  w h i l e t h e o p e r a t o r had  a v e r y p r e c i s e measure o f the f l i g h t  amplitude.  necessary  u n s a t i s f a c t o r y , p a r t i c u l a r l y where  By u s i n g t h e t r a n s d u c e r o u t p u t  53C  effect,  expended a t a g r e a t e r r a t e . independent  i n the  carbohydrate.  f r e q u e n t , as i t r e q u i r e d the c o n t i n u o u s test  c o u l d be  statements  s h o u l d i n c r e a s e , w i t h the  s e r v e as an  o b s e r v a t i o n o f the and wing b e a t  to i n c r e a s e  type o f i o n e x e r t e d a s t i m u l a t i n g  A stop watch proved  control  the  o b t a i n a b l e from a g i v e n q u a n t i t y o f  example, i f a c e r t a i n  consequence that  the e f f e c t  o f i n s e c t s , as i n d i c a t e d by  "weather-sense".  flying  integration  Slope  the Dual T r a c e U n i t  below an a r b i t r a r y minimum  at the V e r t i c a l  Out  T h i s output  amplified  r e l a y which i n t u r n c o n t r o l l e d  was  terminal only and  rectified  the P r e c i s i o n Time-It  clock.  18  The  same r e l a y  s h u t t e r when f l i g h t itself,  i t was  ceased.  3).  The  Rather  found p r e f e r a b l e  w i t h a s h u t t e r about Plate  c o u l d be u t i l i z e d  2! cm  to o p e r a t e the a i r stream  than t u r n o f f the blower  t o s h u t o f f the a i r s t r e a m a b r u p t l y  i n front  o f t h e mounted i n s e c t  sudden movement o f t h e n e a r b y  s t i m u l u s t o resume  s h u t t e r was  rest  thus e l i m i n a t i n g  p e r i o d s o f the  ( F i g . 18 an  and  additional  flight.  L a t e r t h e r e c o r d e r - d r i v e m o t o r s were a l s o relay,  motor  t h e gaps i n t h e g r a p h s  controlled  by  this  c o r r e s p o n d i n g t o the  insect.  (ix) Pull recording  The  f o r c e m e a s u r e d by means o f the VTVM o f F i g . 6 was  plotted  v e r s u s t i m e , b u t h e r e , e v e n more so t h a n i n t h e c a s e o f t h e wing f r e q u e n c y , l a r g e random v a r i a b i l i t y n e c e s s i t a t e d recording  t o e n a b l e an  examination  continuous  beat  graphical  o f the p u l l p a t t e r n s under v a r i o u s  conditions.  A s i m p l e two  s t a g e DC  of approximately 1 v o l t  t o be  amplifier  enabled  the t r a n s d u c e r o u t p u t  r e c o r d e d on a s e c o n d E s t e r l i n e - A n g u s  graphical recorder.  One  could also  e l e c t r o m e t e r w h i c h has d e s i g n e d f o r use  have u s e d  a built-in  h i g h i n p u t impedance DC  210  amplifier  d i r e c t l y w i t h an E s t e r l i n e - A n g u s .  F o r v e r y low  i n p u t a p p l i c a t i o n s , P r a g l i n and B r e c h e r  have d e s i g n e d a s t a b l e and for  the ready-made K e i t h l e y Model  t h e 5734 t r a n s d u c e r .  linear  high gain amplifier  (1955)  specifically  1$  G.  Application of the stationary f l i g h t apparatus  ( i ) Experiments i n ionized a i r (a) Ion sources - Two tritium ion sources were positioned on either side of the a i r jet i n front of the insect and the Beckett probe was placed about 1 cm behind. current of approximately 5 x l 0 ~  1 0  This arrangement gave a probe  simp.  Turning on the a i r jet did not  alter this value appreciably, indeed sometimes even increasing the ion current, indicating entrainment of ions by the a i r stream.  The ion  velocity was estimated from mobility data to be at least twice that of the a i r jet generated by a hair-dryer type blower and motor.  Ionized  molecules could therefore d r i f t across and thoroughly mix with a slower a i r current. (b) Grounding the insect - An insect suspended on an insulator i n a unipolar atmosphere builds up a static e l e c t r i c a l charge and thus limits the number of ions which can reach i t s surface.  The  aluminum f o i l attached to the animal was therefore grounded by means of a very fine copper wire loosely strung from the roof of the wind tunnel.  Its presence had negligible effect on forces measured by the  transducer.  The e l e c t r i c a l resistance of the integument and of the  drop of beeswax was then determined by charging a 0.01juf condenser to l/e of the charging potential.  RC time constants of approximately  100 seconds or longer indicated a resistance greater than 1 0 ^ ohms. An ion current of 10  amp would then produce at least a 10 volt drop.  Although this figure was small relative to the 500 volt potential of the ion source, to ensure optimum ion current at a l l times the integument  20; of the insect was e l e c t r i c a l l y grounded by bridging the beeswax with inorganic s i l v e r micropaint Mich.).  (SCP 12, Micro-Circuits Company, New  Buffalo,  This l e f t in the c i r c u i t only a resistance of less than 10  ohms due to the  exoskeleton.  The aluminum f o i l s themselves were coated with beeswax to reduce the number of ions bypassing the insect via a low resistance path to ground. Total ion currents through the insect i t s e l f were between 3x10*" P  and 6 x l 0 : 7  10  amp.  (c) Experimental controls - When preliminary f l i g h t s had revealed the marked differences in behaviour between similar individuals, internal control seemed most l i k e l y to offer the best means of detecting small magnitude changes. the measured quantities was  A standard deviation of  therefore determined for each individual  insect from a number of control runs; the runs under the desired conditions were then compared only with the insect's own vations.  control obser-  Each test run i n ionized a i r was usually preceded by  control runs and followed by one i n unionized a i r .  two  It proved to be  d i f f i c u l t to find specimens which would f l y well enough for several successive measurements, and many flight-runs were therefore l e f t unfinished.  For this reason the number of complete recordings remained  r e l a t i v e l y small.  No selections as to size, sex:, and age of the f l i e s  were made. Although insects could be made to resume f l i g h t immediately after feeding, some evidence of fatigue persisted i n the succeeding run.  21. Consequently after feeding 5 mg. of 20$ sucrose solution, specimens were allowed to rest for a half hour period before the next experimental run. A number of t r i a l s were made i n which the insect was not flown to exhaustion before feeding.  As these did not reveal any obvious  new features, and since quantitative comparisons are more d i f f i c u l t , they are not included i n the subsequent calculations. ( i i ) Addition of carbon dioxide to ionized a i r In an effort to smooth out some of the fluctuations i n the recorded quantities the concentration of COg i n the tunnel was increased up to 15$.  Above this l e v e l a c t i v i t y ceased altogether. The p o s s i b i l i t y  existed that with higher concentrations of blood COg the strong peaks of a c t i v i t y and the subsequent minima would not appear so pronounced and thus enable a better evaluation of the ion study. Carbon dioxide was metered into the system by the method i l l u s t r a t e d i n F i g . 11.  A constant flow rate was maintained by keeping  a fixed pressure at an o r i f i c e leading to the blower.  A water manometer  gave an expanded scale when the mercury manometer read below 40  mm.  Concentrations up to 15$ were readily achieved, but above this level the gas diffused out of the tunnel almost as fast as i t entered (Fig. 12). To obtain an estimate of the time required for the COg concentration to reach a steady state, and also to see i f appreciable concentration gradients existed i n the tunnel, a small sample was withdrawn and analyzed at one minute intervals after the CO^ valve was opened.  After obtaining a concentration-time curve at one point i n  the tunnel, i t was flushed with fresh a i r and the process repeated at  22: several other points  ( F i g . 13).  F i g . 14 shows t h a t a t t h e p a r t i c u l a r  p r e s s u r e o f 35 cm. HgO t h e COg l e v e l r e m a i n e d 4 minutes  throughout  (iii)  By  Use o f i n s e c t  repellents*  i n t r o d u c i n g v a r i o u s r e p e l l e n t s and a t t r a c t a n t s  olfactometer.  mill  c o u l d be u t i l i z e d  blower b e f o r e r e a c h i n g the j e t n o z z l e .  A i r from a compressor  I n t h i s way t h e v e l o c i t y  u n a l t e r e d , while the c o n c e n t r a t i o n of r e p e l l e n t site  Insect  During Muscina  o f the j e t remained  was h i g h e s t  at the  t h e summer months a s u f f i c i e n t  number o f L u c i l i a and  c a n be caught n e a r t h e n a t u r a l b r e e d i n g g r o u n d s a d j a c e n t t o A week's s u p p l y may be t a k e n w i t h an i n s e c t  a t one e x c u r s i o n and t r a n s f e r r e d  available  at  repellent,  rearing  d a i r y and p o u l t r y b a r n s .  hot  the l i q u i d  was  of the i n s e c t .  D.  net  a i r i n a closed  the f r e s h a i r stream near the  s a t u r a t e d by p a s s i n g i t t h r o u g h a f l a s k c o n t a i n i n g t o the blower.  i n t o the  as an e n t o m o l o g i c a l  S i n c e the a p p a r a t u s d i d not r e c i r c u l a t e  t h e c h e m i c a l s were i n t r o d u c e d i n t o  and t h e n c e  constant a f t e r  t h e whole volume o f t h e a p p a r a t u s .  wind t u n n e l the f l i g h t  system,  essentially  immediately as d e s s i c a t i o n can r e s u l t  and d r y w e a t h e r .  Water must be made w i t h i n a few h o u r s i n  S e v e r a l d a y s ' s u p p l y o f w a t e r may be i n t r o d u c e d  one t i m e by i n v e r t i n g a f i l l e d  * Dr. Robert Wright, B r i t i s h experiment  to cages.  g l a s s j a r onto f i l t e r  Columbia  Research Council,  and k i n d l y p r o v i d e d the r e p e l l e n t s .  paper  in a  suggested  this  23 p e t r i dish.  If eggs are required for continued breeding, scraps of  fresh l i v e r , meal, f i s h , etc., may be placed on the moist paper daily and the eggs removed (Peterson 1953). Insects not needed for egg-laying do not require a protein diet and may be maintained s a t i s f a c t o r i l y for several days on alone.  carbohydrate  Wicks of dental gause dipping i n 5$ sugar solution are recommended  for feeding but sugar cubes lying i n the cage seem to serve the purpose satisfactorily. Eggs recovered from the breeding cages are placed on a l a r v a l medium consisting of ground meat or a mixture of yeast, milk and agar boiled in water.  Active maggots are best kept at a temperature of 23-25°C  and a humidity of 70$.  ;  To reduce the disagreeable odour, the protein  content of the culture medium i s kept low.  When f u l l y grown, the larvae  crawl into loose dry sand or sawdust to pupate and the adults emerge i n approximately  two weeks time.  In the f a l l and winter months these insects tend to deposit fat in preparation for hibernation rather than produce 'eggs (Galtsoff 1937).  Fresh l i v e r must therefore be available before and during the  c r i t i c a l few days that the young female w i l l oviposit.  24  3.  A.  RESULTS OF  O b s e r v a t i o n s on  Hollick  insect  AIR-IONIZATION STUDIES  flight  (1940), working w i t h Muscina s t a b u l a n s ,  t h a t w i n g movements i n f r e e f l i g h t  differed significantly  o f the  same i n s e c t h e l d  insect  i s c o n t i n u a l l y t r y i n g to a c c e l e r a t e  the  point  stationary in s t i l l  of attachment, t h i s  could  I t i s n o t e w o r t h y however t h a t  relatively  stable u n t i l  sistent  w i t h the  l a r g e l y by  the  per  that beat  that  generally  of  being  flight  connection  potential  that  by  Hocking an  the  only  other the  pair.  stroke  free  of  irregular pull frequency  remained sharply  i s con-  frequency i s governed (Pringle  1957)  at  rapid  n e r v e i m p u l s e had  ( p . 230)  points  antagonistic  such a  t o be  transmitted  out  that  Pringle  a c t i o n between t h e  a c t i v e l y i n response  two  to  H o c k i n g o f f e r s the a l t e r n a t i v e  and  the  action  so p r e d i c t s a s l i g h t l y  nerve stimuli..  i n a m p l i t u d e a p p e a r e d i n the  t r a c e s on  our  s l o w sweep s p e e d , a b o u t 50-100 s u c c e s s i v e this  fastened  stability  immediately f o l l o w i n g  i s powered b i o l o g i c a l l y ,  During  the  those  off rather  to take place  a m p l i t u d e between s u c c e s s i v e  once.  the  wing beat  This  the  itself  the w i n g s y s t e m  muscles which each c o n t r a c t  stretched  explanation  the  from  195l).  found i t necessary to p o s t u l a t e sets of  explain  a c c e p t e d view t h a t  t e t a n u s would r e s u l t i f one  In t h i s  twist  c r u i s i n g speed.  mechanical resonance of  (Boettiger  and  Since  n e a r e x h a u s t i o n when i t f e l l  which enables a c t i v e muscle c o n t r a c t i o n s rate  air.  i n part  observed.  t o a minimum n e a r 2/3  demonstrated  No  decreasing  such p e r i o d i c v a r i a t i o n s  oscilloscope.  With a  very  w i n g - b e a t s were d i s p l a y e d  i n t e r v a l approximately 5 nerve pulses  should  have  at  25 arrived, and one would therefore expect a step in amplitude every 10 - 20 beats.  The uniform amplitude of the wing beats tends to support Pringle's  theory of myogenic contraction. In tethered f l i g h t insects have been observed to attempt, in varying degrees and i n various ways, to free themselves from the point of attachment.  These efforts may take the form of twisting by  increasing the amplitude of one wing beat or, as i n our observations, by periods of extraordinarily strong f l i g h t .  If one examines Hocking's  data on parasite drag as a function of velocity (pp. 66-267) i t i s apparent that the horizontal force at maximum speed i s almost equal to the weight of the insect.  Our measurements showed however that an insect  weighing 20^-25 mg frequently recorded forces of 50-60 dynes (twice i t s weight) for short durations, followed by periods of r e l a t i v e l y weak flight.  One could reason that the insect overexerts i t s e l f for a short  time, then slows down to recover.  As already noted, greater p u l l i s  brought about mainly by a change i n the angle of attack of the wings and in the amplitude of the wing beat, rather than by an increased beat frequency.. When interpreting the results i t i s necessary to remember that the insect acquires different characteristics after some time on the m i l l .  Flight periods generally become longer, but they are weaker,  more erratic and show more numerous rest periods.  It seems that although  certain insects have an extremely efficient metabolic system requiring only water and carbohydrate and almost no mineral, l i p i d or protein replacement, s t i l l after prolonged muscular a c t i v i t y catabolic degeneration does become evident.  26 In those cases where a single run appears to be longer or more energetic than the others, one cannot rule out the p o s s i b i l i t y of energy carry-over from the previous run.  For his work on f l i g h t  endurance, Hocking a r b i t r a r i l y defined exhaustion as f a i l u r e to resume f l i g h t after three successive stimulations. We found however that further stimulation sometimes induced up to four minutes more f l i g h t . In any case i t i s impossible to t e l l precisely when the insect has depleted a l l i t s reserves. Atmospheric temperature, pressure, and humidity were recorded but no corrections were made to the results.  Conditions in the laboratory  were f a i r l y uniform over the period during which any given insect  was  being flown.  B.  Insect f l i g h t in an ionized atmosphere  (i) Description of f l i g h t records Sample p u l l and wing beat frequency recordings are shown i n Fig.  15 and F i g . 16 respectively. The p u l l recordings generally show  strong f l i g h t for the f i r s t  few minutes after the commencement of a  run, followed by an alternation of weaker and stronger a c t i v i t y .  The  average forward force diminishes gradually as the energy reserves are expended.  Superimposed on the major features are rapid fluctuations  having short periods of several seconds to half a minute.  Consistent  patterns, characteristic of f l i g h t under a particular set of conditions, were not observed on s u p e r f i c i a l inspection.  27 The wing beat frequency i s r e l a t i v e l y much more regular.  A  rested L u c i l i a began f l y i n g at a rate of 200-240 beats per second, dropping off to about 180 per second after 15-30 minutes of f l i g h t . At  the end of a run the frequency f e l l f a i r l y rapidly to around 140-160,  when f l i g h t ceased altogether.  As i n the case of the p u l l recordings  each run showed novel variations and no features common to particular conditions could be established. Of the thirty sets of records obtained, seven were s u f f i c i e n t l y complete to be used i n the subsequent quantitative analysis.  ( i i ) Duration of f l i g h t Flight times for those runs i n which measured amounts of sugar solution were fed are shown i n Table 1.  Standard deviations for  each specimen were calculated using the relation  0" jr^T IL 3  It i s seen from the summary i n Table 3 that two f l i g h t s with positive ions and two with negative ions f e l l outside the 2o~limits (5$ probability), but since these times are not consistently longer or shorter they cannot be regarded as significant, and could be attributed to sudden and unpredictable changes i n the character of the insect% behaviour.  ( i i i ) Power and energy of insects i n f l i g h t The total power required by an insect i n free flight i s the sum of two terms:  the power needed to maintain the insect i n the a i r ,  and the power needed for forward movement (Hocking p. 269). A semiempirical expression for the total power i s :  P= ^  + \ p CD S V  3  where the f i r s t term describes the power to remain a l o f t , and the second  28  term  relates  to the motive  power, and where  b = a c o n s t a n t f o r each  insect,  & = the amplitude  o f the wing beat  n = the wing beat  frequency,  i n radians,  P = the a i r d e n s i t y , C = the d i m e n s i o n l e s s d r a g c o e f f i c i e n t ,  r a n g i n g f r o m 1.1  t o 2.3,  S = the c r o s s s e c t i o n a l area of the thorax, V = the f l i g h t  The parasite (cf.  velocity.  force required  t o m a i n t a i n a g i v e n v e l o c i t y , known a s  d r a g d , i s r e p r e s e n t e d by the i d e a l p  Hocking  In  P  the present apparatus  n o t known by d i r e c t  to  dp i s r e c o r d e d : found  d = P  velocity  o f the i n s e c t  However, a v o l t a g e v p r o p o r t i o n a l  c v , where c i s a c o n s t a n t , i n o u r case  from the c a l i b r a t i o n  curve  20  (Fig. 10).  t h e above two e q u a t i o n s and s u b s t i t u t i n g  dp one o b t a i n s an e q u a t i o n c o n n e c t i n g P d i r e c t l y w i t h v :  It required  may be assumed t h a t  to remain  values),  ( e . g . see H o c k i n g  one may n e g l e c t t h e e f f e c t  on t h e t o t a l power r e q u i r e m e n t . i s nearly  second  since f o r small insects  a i r b o r n e i s much l e s s  movement a t h i g h speeds  b/9n  the f l i g h t  measurement,'  By e l i m i n a t i n g V f r o m for  formula  JL = l - ^ C p S V *  p . 268)':  is  dynes/volt  hydrodynamic  t e r m Kv  constant. will  t h a n t h e power f o r f o r w a r d p . 257 and p . 270 f o r t y p i c a l  of variations  i n t h e t e r m b/(9n  I t i s probable that  I n the ensuing d i s c u s s i o n ,  be c o n s i d e r e d .  t h e power  in fixed  flight  therefore,  only the  29  For purposes of comparing insect responses under different atmospheric  conditions, i t i s desirable to determine the t o t a l energy  (rather than the power at any instant) expended by an insect after being fed a measured quantity of sugar solution.  Since Energy = Power x Time =  ( K v ) ( t ) , one may find a quantity proportional to energy by integrating z  a plot of v *versus t, K being unknown. 3//  Relative energies are then  treated by s t a t i s t i c a l methods to find i f significant changes due to the presence of ions have occurred. The information from the graphical recorder gives only the voltage v versus time t, so i n order to get the v^-t curve one has to regraph each point, raised to the 3/2 power. f i r s t marked o f f i n one minute intervals.  The raw records were  An average value of v was  chosen in the interval, then raised to the 3/2 power by slide rule, and plotted without intermediate tabulation. Wherever large or rapid changes occurred, intervals smaller than one minute were chosen.  A sample  transformation i s shown i n F i g . 17. Each graph was integrated three times by means of a planimeter, and the average value of the area tabulated (Table 2).  The standard  deviations were computed separately for each insect from the control runs i n ionized a i r using the expression  0~  _i  The results of these calculations are shown i n Table 2 and i n Table 3.  Six out of the nine runs taken with negative ion excess show  energies larger than the mean energies (obtained from control runs) by more than one standard deviation <T, while only one out of nine was smaller.  Two f l i g h t s out of the nine under these same conditions showed  energies just s l i g h t l y larger than the 2<T(5% probability) l i m i t s ,  30)  whereas none under p o s i t i v e Two  out o f e i g h t  ionization  show a c o m p a r a b l e  runs taken w i t h p o s i t i v e  variation.  i o n excess produced e n e r g i e s g r e a t -  e r t h a n t h e mean by one <r, w h i l e t h e r e m a i n d e r were unchanged. is  some i n d i c a t i o n  greater activity,  from these data that  to confirm these  The a p p a r a t u s as d e s c r i b e d was and t h e t i m e v a r i a t i o n s  e n e r g y , as has been  s e e n , had t o be  A p r o b a b l e improvement  Pringle  exhibit  i n p a r t i c u l a r when i o n i z e d n e g a t i v e l y .  have t o be c o l l e c t e d  t h e magnitude  flight  wings  i n a manner v e r y d i f f e r e n t  d i f f i c u l t y would a l s o  primarily  o f the f o r c e s  from that  s t u d y on i n s e c t Lucilia  involved.  i n Appendix  i t i s dangerous  Power  t o use  flight.  t h e method o u t l i n e d  r a n g e and  conclusions  i n the  flies,  i s o n s a s t o t h e o r d e r o f magnitude  I f one  t a k e s 0.5  p r o d u c e d by L u c i l i a o f 1.5>  Appendix.  in flight  s p e e d does not p r o v i d e  s e r i c a t a o r Muscina s'tabulans.  s e c t i o n a l a r e a o f 8 mm*",  o f v e l o c i t i e s and p u l l  can be made.  v o l t s a s a measure o f t h e a v e r a g e and a s s u m i n g  deflection  a drag  0 o f 0.00120 gm/cc, and a mean t h o r a c i c one  and  and w i t h t h e h e l p o f h i s d a t a compar-  or Muscina i n f l i g h t ,  an a i r d e n s i t y  their This  C h r y s o p s n i g r i p e s u s e d by H o c k i n g has a p p r o x i m a t e l y t h e same s i z e as o u r t e s t  and  B.  t o draw  found i n f r e e  p u l l and s p e e d o f i n s e c t s  i n f o r m a t i o n on t h e s p e c i e s  i n t e n d e d to study  i n s e c t s which are l i k e l y  be overcome by  ( i v ) Forward  Hocking's  on f i x e d  More d a t a  computed f r o m t h e f o r c e d a t a .  ( p . 80) warns t h a t  energy from r e s u l t s  (25 mg)  a  findings.  i n t h e method i s o u t l i n e d  about  weight  there  o r m e t a b o l i c e f f i c i e n c y , when t h e a i r s u r r o u n d i n g  them i s i o n i z e d , and will  insects during  Thus  obtains f o r P = ("j?^ ^) * ( 0  c v  ) ^  X  coefficient cross  31  a v a l u e o f 4700 e r g / s e c .  U s i n g t h e g r a p h o f power v e r s u s a i r s p e e d g i v e n by H o c k i n g (p.  2 7 0 ) , one  finds  cia/sec, o r n e a r l y  that  t h i s power p r o d u c e s a v e l o c i t y  10 mph.  This  figure  H o c k i n g s e x p e r i m e n t a l d a t a on f l i g h t be n o t e d t h a t  f o r short  producing deflections almost  o f up t o 1.5  parasite  v e l o c i t y may  obtains:  V =  ~ --%•  =  into  = 472  fCoS  further  drag versus a i r speed  t h e s e s p e c i e s were c a p a b l e o f  volts,  this  being equivalent  calculated  Hocking's graph t h i s  •^•^^B^V  this  = cv.  Substituting  e q u a t i o n and  t h e above  solving for V  cm/sec. i n c l o s e agreement  one  w i t h the  figure  c h e c k can be made f r o m H o c k i n g ' s g r a p h o f p a r a s i t e (p. 266).  Our  calibration  corresponds to a v e l o c i t y  a g a i n i n good agreement  (v)  Effect  d a t a show t h a t o f 10 d y n e s .  as t h e COg  o f Carbon  d i o x i d e and i n s e c t  c o n c e n t r a t i o n was Flight  f r o m 10-15$ COg, and above t h i s  c o n c e n t r a t i o n was  On cm/sec,  w i t h the observed speeds.  c h a n g i n g the b a s i c p a t t e r n .  the s t a t i s t i c a l  0.5  o f a p p r o x i m a t e l y 500  repellents  A p r o g r e s s i v e d e c r e a s e i n the s t r e n g t h o f f l i g h t  in  to  from the e q u a t i o n r e l a t i n g  f r o m t h e t r a n s d u c e r i s p r o d u c e d by a f o r c e  evident  It should  cm/sec o b t a i n e d a b o v e .  One  volt  a l s o be  d r a g . a n d a i r s p e e d dp  v a l u e s f o r the parameters  490  (pp. 301-302).  with  double t h e i r normal a i r speed.  The  of  490  i s i n r e a s o n a b l e agreement  speeds  time i n t e r v a l s  o f about  discussion normal.  level  increased, without  became  essentially  movements were e x t r e m e l y weak ceased a l t o g e t h e r .  originated  The  i n runs i n which the  data used COg  32  The effects of two commercial insect repellents are i l l u s t r a t e d by the sample recording of Fig. 18.  Although insects generally flew  more strongly when these chemicals were f i r s t introduced, the p u l l returned to normal after a few minutes.  This may be due to exhaustion,  or to inurement of the chemoreceptors which become less,sensitive under prolonged stimulation (cf. mammalian olfactory sensation).  The study  of the effects of insect repellents was not pursued i n greater detail..  C.  F i n a l discussion  In these investigations attention should be given to the mechanism by which the ions could exert their effects on the insects. The sites which seem most l o g i c a l are the tracheal system, the external sensory system, or the external integument i t s e l f .  Krueger's work on  the mammalian trachea, in which negative ions increase the c i l i a r y rate and positive ions decrease the rate and reduce mucous flow, definitely shows that the l i n i n g of the upper respiratory tract i s affected by ions.  The tracheal system of insects d i f f e r s however from the mammalian  respiratory system i n several important respects: a dry wax-covered layer of cuticle (Roeder 1953)  i t i s lined with instead of a mucous  membrane well-supplied with circulatory and nervous elements; and the diameters of the tracheoles are much smaller than those of  lung-breathing  animals. Although the fine branches of the ultra-tracheolar network are f i l l e d with l i q u i d , this tracheolar f l u i d i s known to be retracted during a c t i v i t y to allow increased^ventilation. From a knowledge of diffusion rates, kinetic theory, and recombination coefficients i t can  33 be estimated that a large proportion of the ions entering the spiracles i s possibly discharged before the ions reach the terminal c e l l s (see Appendix A).  Since i t i s known that almost no diffusion takes place  between the a i r tubules and the blood (Williams 1953, Snodgrass 1956), ions, such as Og, would have to travel the whole length of the tracheole before reaching an enzyme system at the terminal c e l l .  There i s ,  therefore, some reason to believe that the tracheolar system i s not the only channel through which ions may affect insects, i f they do so. The olfactory organs of insects (the s e n s i l l a lasiconica, the s e n s i l l a coelonica and ampulacea, and the s e n s i l l a placodea) are located externally around the mouth parts and antennae.  The exoskeleton  in these regions i s perforated by pore ducts, beneath which are situated the olfactory nerves covered only by a very thin membrane allowing diffusion of odorous substances (Frisch 1954).  As well as the sensory  pores, a network of fine h e l i c a l pore canals permeates the integument (Roeder 1953) enabling part of the Og uptake and 2 5 $ of the COg output to be exchanged by cutaneous diffusion (Weber 1954).  It i s conceivable  that a i r ions could reach the insect's system by these pathways as easily as through the tracheoles. With the limited number of complete t r i a l runs, statements on the effect of a i r - i o n i z a t i o n on insect metabolism can only be attempted with caution.  The analysis seems to indicate that an excess of negative  a i r ions, i n particular, results i n an enhanced insect a c t i v i t y . It appears probable that our laboratory findings give substance to the previous qualitative observations on a c t i v i t i e s and a i r - e l e c t r i c a l weather factors; a continuation of the experiments along the same l i n e s may contribute to a c l a r i f i c a t i o n of the question of "weather sense" i n insects.  34 APPENDIX A  An estimate of the mean distance through which ions diffuse along a tracheole of radius 10/t.  The procedure w i l l be to calculate the average number of c o l l i s i o n s per second that each ion i n a gas undergoes with the walls of the container; then to determine the lifetime of an ion from recombination data and the c o l l i s i o n frequency; and f i n a l l y to estimate the distance the ion diffuses or i s propelled by respiratory movements during this lifetime.  (i) C o l l i s i o n frequency with the wall It i s shown from Kinetic theory (eg. Moore, 1955, p. 167) that the number of molecules striking unit area per second i s l/4 nc, where n i s the number of molecules per cc and c i s their mean speed, o  19  At 20 C, n = 2.5x10  per cc.  For an ion consisting of a cluster of  five Og molecules c = 200 m/sec at room temperature.  The total number  of c o l l i s i o n s with the walls of area A i s l/4ncA per second, or l/4y-cA, where N i s the number of molecules i n the box of volume V. of c o l l i s i o n s per second per molecule i s then -^-'^ycA=  The number . For  a long thin cylinder with radius R « t h e length L, this becomes c_JjL^L - c tiy xoo m//u^ 7 gee" tubule 1  o  tfir K  L  Zn  of radius 10^u..  r  e x p l i c i  2  <  10*10  =  m  1 G  f  o  r  a  ( i i ) Average lifetime of an ion Nolan and de Sactay (192?) have derived recombination equations for small ions and large nuclei, which, i n a unipolar atmosphere with - ^ j r ~ 1. ' ^> $  no rate of production, reduce to  r>  z  r>t  »  w  n  e  r  \ i s the  e  recombination coefficient, n^ i s the concentration of small ions, and N^ i s the number of uncharged large nuclei.  Since each c o l l i s i o n  with the wall may as an approximation be considered equivalent to a c o l l i s i o n with a large nucleus, one can use the above equation to find the number of c o l l i s i o n s an ion makes before losing i t s charge. Consider one condensation nucleus of radius 0.2/* and one ion in 1 cc of a gas.  Then the total number of c o l l i s i o n s which the nucleus  undergoes with the ion i s c/U  I£L2*« • ^  a.S  z  However i f n, = 2xl0 , N. = 1, Y)= 5 x l 0 f , then 6  6  But this number of  -5  ions undergoes 2x10 x 2.5 x 10. nucleus.  ^n,= 1  7  per second, that i s , one ion decays per second.  yito'^ptr  = 50 c o l l i s i o n s with the condensation  One can therefore conclude that after 50 c o l l i s i o n s one ion  w i l l lose i t s charge to a nucleus.  In a tracheole with a radius of  10yxthe average lifetime i s therefore J Q ^ = 5X10 ^sec. ( i i i ) Diffusion distance The distance which an Og molecule diffuses during a time a  t may be found from Einstein's diffusion equation D=0.173 — sec,  Ax  - .[ * « o.i7S v  K T «  IO' ": 1  I.13*/OC™.  Ax = 2Dt. Using T h i s  i s  o  n  i  y  about  l/lOO the length of a tracheole. Respiration i s however aided by active pumping movements of the abdominal segments so that the tracheal trunks behave l i k e bellows.  I f the speed of the a i r streaming into the  *c  36 tracheole were as high as 20m/sec, the distance travelled i n 5xl0~^sec i s s t i l l only 10~ cm, about l / l O the length of a tracheole. be noted that the tracheole tapers to a diameter of O^^&t  It should i t s inner  extremity, thus further increasing the probability of decay.  (iv) Estimate of distance which an ion travels in the human respiratory tract Consider the nasal passage as a tube of cross sectional area 2 1 cm .  During a deep breath about 2 l i t r e s of a i r may be inspired in  half a second.  Thus the velocity of the a i r in the tube i s 40 m/sec.  The number of c o l l i s i o n s an ion makes with the tube wall i s a. R or 17,700 per sec. Assuming again that an ion can survive an average 50 x 10~^ -3 of 50 c o l l i s i o n s , the mean lifetime w i l l be ^. „ „ — = 2.8 x 10 sec,  3 and i t w i l l travel a distance of 4 x 10 approximately  -L. i I  x 2.8 x 10  -3 — 11 cm.  This i s  the length of the nasal passage and takes the ion into the  trachea where the aforementioned specific effects have been observed.  37 APPENDIX B  Improved experimental arrangement f o r f u r t h e r  investigation  So that n a t u r a l c o n d i t i o n s be reproduced as c l o s e l y as p o s s i b l e it  seems e s s e n t i a l that the speed of the a i r moving past a tethered  i n s e c t must at a l l times be equal to the speed the i n s e c t would have i f i t were i n f r e e f l i g h t .  H o l l i c k ( 1 9 4 0 ) observed that wing movements  of Muscina stabulans i n s t a t i o n a r y f l i g h t were i d e n t i c a l with those i n free f l i g h t only when the drag of the a i r stream j u s t balanced the measured forward p u l l .  T h i s means that i n our f l i g h t m i l l the output  of the transducer must be made zero at a l l times.  One  could acheive  t h i s c o n d i t i o n most simply by manually a d j u s t i n g the speed of an  exhaust  blower, or b e t t e r perhaps by l e t t i n g the transducer operate a s e l f r e g u l a t e d e r r o r - a c t u a t e d servomeonanism which c o n t r o l s the speed of the blower.  The f l i g h t speed of the f l y i s then equal to the a i r speed  i n the wind tunnel and may wire anemometer.  be recorded by means of a c a l i b r a t e d hot  (To reduce turbulence the i o n sources may  be removed  from t h e i r holders and placed some distance ahead and to the s i d e s of the i n s e c t . )  From a second transducer nearby on which i s mounted a dead i n s e c t one obtains a voltage p r o p o r t i o n a l to p a r a s i t e drag dp.  The  power i s found simply by e l e c t r o n i c a l l y m u l t i p l y i n g the anemometer voltage by the p a r a s i t e drag.  (P=d V=Force x p  *  d  i  f :  a  n  c  e  ^  Energy/time=Power  u xme  The q u a n t i t y most o f t e n r e q u i r e d , the energy, i s then obtained by p l a n i m e t r i c or e l e c t r o n i c i n t e g r a t i o n of the power-time r e l a t i o n without the intermediate i n a c c u r a c i e s i n v o l v e d i n the tedious task of r a i s i n g  38 the force graph to the 3/2 pov/er.  Also, absolute values of energy could be  obtained and not merely relative values.  ; 39  BIBLIOGRAPHY  ANDREWARTHA, H.G., and BIRCH, L.C., (1954) "The D i s t r i b u t i o n and Abundance o f A n i m a l s " , (Book) U n i v e r s i t y o f C h i c a g o P r e s s , C h i c a g o . BERG, H., (1955) " W i d e r s p r e c h e n d e A u s s a g e n i n d e r m e d i z i e n i s c h e M e t e o r o l o g i e " , Munchener M e d i z i e n i s c h e W o c h e n s c h r i f t , .27(23), 10: June 1955, pp. 749-752. a  BOETTIGER, E.G., ( l 9 5 l ) " S t i m u l a t i o n of the f l i g h t A n a t o m i c a l R e c o r d , v o l . I l l , 1951, p . 443.  m u s c l e s o f the f l y " ,  BUETTNER, K.J.K., ( l 9 5 7 ) " P r e s e n t knowledge on c o r r e l a t i o n s between w e a t h e r c h a n g e s , s f e r i c s , and a i r e l e c t r i c space c h a r g e s , and human h e a l t h and b e h a v i o u r " , F e d e r a t i o n P r o c e e d i n g s ( B a l t i m o r e ) , 16(2:), J u l y 1957, pp. 631-637. CHALMERS, J.A., London.  (1957) " A t m o s p h e r i c  Electricity",  (BooR),  Pergamon P r e s s ,  CUPCEA, S., DELEANU, M., and FRITS, T., (1959) " E x p e r i m e n t e l l e U n t e r s u c h u n g e n uber den E i n f l u s s der L u f t i o n i s a t i o n a u f p a t h o l o g i s c h e V e r a n d e r u n g e n d e r Magenschlwmhaut", A c t a B i o l o g i c a e t M e d i c a G e r m a n i c a , Band 3, H e f t 5, 1959, pp. 407-416 DANFORTH, C.H., (1952:) "An e x p e r i m e n t to t e s t t h e e f f e c t , i f any, o f d i f f e r e n c e s i n i o n i z a t i o n l e v e l s o f t h e a i r on the g r o w t h o f c h i c k e n s " , 1 March 1952, R e p o r t t o W e s i x E l e c t r i c H e a t e r Company, San F r a n c i s c o . von DESCHWANDEN, J . , and MILLER, B., (1952) " L ' i n f l u e n c e de I ' a l t i t u d e e t de l a c o n d u c t i b i l i t e e l e c t r i q u e de l ' a i r s u r q u e l q u e s e l e m e n t s de l a c i r c u l a t i o n p e r i p h ^ r i q u e " , G a z e t t e M e d i c a l e de F r a n c e , 5 9 ( 2 2 ) , S u p p l . 43-44, 1952. DESSAUER, F., ( l 9 3 l ) "Zehn J a h r e F o r s c h u n g a u f den P h y s i k a l i s c h M e d i z i e n i s c h e n G r e n z g e b i e t " , ( B o o k ) , George Thieme, L e i p z i g . DUBOS, R . J . , (1959) " C l i m a t e a f f e c t s h e a l t h " , S c i e n c e News 75.(20), 16 May 1959, p . 310.  Letter,  EDDY, W.J., STRELTZOV, L., WILLIAMS, J . , SCIORTINO, L., ( l 9 5 l ) "The e f f e c t o f n e g a t i v e i o n i z a t i o n on t r a n s p l a n t e d t u m o r s " , C a n c e r R e s e a r c h , 1 4 ( 4 ) , 1951, p. 245. FRAENKEL, G., and GUNN, D.L., (1940) "The o r i e n t a t i o n o f animals', K i n e s i s , t a x e s , and compass r e a c t i o n s " , O x f o r d , the C l a r e n d o n P r e s s , 1940. FREY, W., (1951) " L u f t e l e k t r i s c h e U n t e r s u c h u n g e n " , V e r e i n s b e r i c h t , S c h w e i z e r i s c h e M e d i z i e n i s c h e W o c h e n s c h r i f t , 8 l ( 4 7 ) , 1951, p . 1156.  40 (1952) "Die I o n i s a t i o n der Luft i n geschlossenen Raumen", Schweizerische Medizienische Wochenschrift, 8_2(39), 1952, pp. 994-6. (l955) "Atmosphare und vegetative Nervensystem", Acta Medica Scandinavica, Suppl. 307, 1955, pp. 53-56. (1956) "Die atmosptiarishe R a d i o a k t i v i t a t a l s b i o l o g i s c h e r R e i z " , Medizienische K l i n i k , ' j j l , 1956, pp. 577-583. 1  FRIEDMAN, S., (l959) "Sustained f l i g h t i n Phormia (by a new method) and i t s e f f e c t s on blood pH", Journal o f Insect Physiology, 2(2), May 1959, PP. 118-9. von FRISCH, K., (1954) "The Dancing Bees", (Book), Methuen, London, E n g l i s h E d i t i o n 1954. GALTSOFF, LUTZ, WELCH and NEEDHAM, (l937) " C u l t u r e methods f o r i n v e r t e b r a t e animals", (Book), Comstock, Ithaca N.Y., 1937, pp. 414-417. GUTMANN, M.J., (l957) "The i n f l u e n c e of sorocco weather on b r o n c h i a l asthma i n Jerusalem", Acta Medica O r i e n t a l i a , 1 6 ( l l - 1 2 ) , 1957, pp. 255-261. HARTWEGER, E.W.S., (1956) "Zur Therapie der W e t t e r f u h l i g k e i t und Wetterempfindlichkeit ('Fohnerkrankungen*)", Medizienische K l i n i k , £1(12), 23 Mar. 56, pp. 474-6. HICKS, W.W., and BECKETT, J.C., (1957) " C o n t r o l of a i r i o n i z a t i o n and i t s b i o l o g i c a l e f f e c t s " , AIEE T r a n s a c t i o n s , 7 6 ( 3 0 ) , P t . 1, 1957 pp. 108-112. HOCKING, B., (1953) "The i n t r i n s i c range and speed of f l i g h t o f i n s e c t s " , The Transactions o f the Royal Entomological S o c i e t y of London, 104, P t . 8, 23 October 1953, pp. 223-345. HOLLICK, F.S.J., (1940) "The f l i g h t o f the dipierous f l y Muscina stabulans", P h i l o s o p h i c a l T r a n s a c t i o n s , 2301 P t . B, 1940, pp. 357-390. ISRAEL, H., (1951) " L u f t e l e k t r i z i t a t und B i o k l i m a t o l o g i e " , Experimental Medicine and Surgery, £ ( 2 - 4 ) , May-Nov. 1951, pp. 322-332. 1  KNOWLES, D.D., and REUTER, E., (1940) "The S t e r i l a m p — I t s e l e c t r i c a l and r a d i a t i o n c h a r a c t e r i s t i c s " , Transactions o f the E l e c t r o c h e m i c a l S o c i e t y , 73_, 1940. KORNBLUEH, I.H., and GRIFFIN, J.E., (1955) " A r t i f i c i a l a i r i o n i z a t i o n i n p h y s i c a l medicine", American Journal of P h y s i c a l Medicine, 3 4 , December 1955, pp. .618-631. KSRNBLUEH, IvH., PIERSOL, G.M. and SPEICHER, F.P., (1956) " R e l i e f from air-borne a l l e r g i e s " , Report to P h i l c o Corporation, 1 Oct. 1956.  1  41 KROGH, A., and WEIS-FOGH, T., ( l 9 5 l ) T h e r e s p i r a t o r y exchange o f the desert l o c u s t ( S c h i s t o c e r c a g r e g a r i a F o r s k a l ) before, during, and a f t e r f l i g h t " , J o u r n a l of Experimental Biology, 2g, 1951, pp. 344-357. M  (1952) "A roundabout f o r studying sustained f l i g h t of l o c u s t s " , J o u r n a l o f Experimental Biology, 2_9, 1952, pp. 211-219. KRUEGER, A.P., HICKS, W.W., and BECKETT, J.C., (1958) " E f f e c t s of u n i p o l a r a i r ions on microorganisms", J o u r n a l of the F r a n k l i n I n s t i t u t e , 26j5(l) J u l y 1958, pp. 9-19. KRUEGER, A.P. and SMITH, R.F., (l957) " E f f e c t s o f a i r ions on i s o l a t e d r a b b i t trachea", Proc. Soc. Exp. B i o l . Med., 96., 1957, pp. 807-9. (1958) "The e f f e c t s of a i r ions on the l i n i n g of mammalian trachea", J o u r n a l of General Physiology, 42_(l), 20 Sept. 1958, pp. 69-82. —•  (l959 ) "Parameters of gaseous i o n e f f e c t s on the mammalian t r a c h e l " , J o r . Gen P h y s i o l . , 42(5), 20 May 1959, pp. 959-969. (l959 ). "Enzymatic b a s i s f o r the a c c e l e r a t i o n of c i l i a r y a c t i v i t y by negative a i r i o n s " , Nature, 183(4671), 9 May 1959, p. 1332. b  KRUEGER, A.P., SMITH, R.F., HILDEGRAND, G.J., and MYERS, C.E., (1959) "Further s t u d i e s of gaseous i o n a c t i o n on trachea", Proceedings of the S o c i e t y of Experimental Biology and Medicine, 102(2), Nov. 1959, pp. 355-7. LION, K.S., (1959) "Instrumentation i n S c i e n t i f i c Research, E l e c t r i c a l Input Transducers", McGraw-Hill Book Co. Inc., N.Y., 1959. LOCKE, J.K., (i960) "Ionized a i r and human h e a l t h " , Popular E l e c t r o n i c s ,  13.(3), Sept. 1960. MARTIN, T.L., (1954) "Production of u n i p o l a r a i r with Radium i s o t o p e s " , Communications and E l e c t r o n i c s , No. 10, Jan 1954, pp. 771-6. MEDINA, A., and GORRITI, A.R., (1954) " A p p l i c a t i o n of i o n therapy i n hypertension", N a t i o n a l M i n i s t r y of P u b l i c Health, Buenos A i r e s , 12 Apr. 1954. MICHALOWICZ, M., (1958) " S e n s i b i l i t e generale et i n d i v i d u e l l e aux processus e l e c t r o l o g i q u e s et electro-magnetiques n a t u r e l s et a r t i f i c i e l s " , Schweizerische Z e i t s c h r i f t f u r allgemeine Pathologie und B a k t e r i o l o g i e , 21, 1958, pp. 575-6. MONTEL, E., (1939) "Sur l a determination des m o b i l i t e s des ions gaseux", Comptes Rendus, 208, 1939, pp. 1141-44. (1944) "Sur une n o u v e l l e m'ethode de mesure des m o b i l i t e s d'ions dans l e s gaz", Comptes Rendus, 2_18, 1944, pp. 391-393.  42.  (1956) "An AC f i e l d mothod f o r m e a s u r i n g t h e m o b i l i t y o f g a s e o u s i o n s " , C.R. A c a d . S c i . , 243.(22), 26 Nov. 56, p p . 1735-7. MOORE, W.J., (1955) " P h y s i c a l C h e m i s t r y " , Second E d . , p f . 167-168.  (Book), P r e n t i c e - H a l l , I n c . ,  NIELSON, C.B., and HARPER, H.A., (1954) " E f f e c t o f a i r i o n s on s u c c i n oxidase a c t i v i t y o f the r a t a d r e n a l g l a n d " , Proceedings o f the S o c i e t y o f E x p e r i m e n t a l B i o l o g y and M e d i c i n e , 86, 1954, pp. 753-756. NOLAN, J . J . , and DE SACHY, G.P., (1927) ^ A t m o s p h e r i c i o n i z a t i o n " , o f t h e R o y a l I r i s h Academy, _3_7, 1927, pp. 71-94.  Proceedings  OKADA, Y., (1938) "Uber den E i n f l u s s d e r I n h a l a t i o n v o n i o n i s i e r t e r J :C L u f t a u f den l e b e n d e n K & r p e r " , Nagoya I g a k k i S a s s h i , 47, 27 D e c . 1938, p p . 771-832. PETERSON, A., (l953) "A Manual o f E n t o m o l o g i c a l T e c h n i q u e s " , Ohio S t a t e U n i v e r s i t y C o l u m b i s , O h i o , pp. 66-67. PRAGLIN a n d BRECHER, (1955) "An a m p l i f i e r flowmeter", pp. 385-7.  Review o f S c i e n t i f i c  (ed.)  5734 b r i s t l e  I n s t r u m e n t s , .26(4), A p r . 1955,  PRINGLE, J.W.S., (1957) " I n s e c t P l i g h t " , Cambridge, ROEDER, K.D.,  f o r t h e RCA  (Book),  (Book), U n i v e r s i t y P r e s s ,  (l953) " I n s e c t P h y s i o l o g y " , ( B o o k ) , W i l e y , New Y o r k .  ROHRER, E . , (1952) " E i n B e i t r a g z u r F r a g e d e r b i o l o g i s c h e n W i r k u n g i o n i s i e r t e r Luft", Schweizerische Medizienische Wochenschrift, 8 2 ( 4 1 ) , 1952, p p . 1063-4. SCHORER, G., (1952) "Uber b i o l o g i s c h e Wirkung i o n i s i e r t e r L u f t " , S c h w e i z e r ,. . i s c h e M e d i z i e n i s c h e W o c h e n s c h r i f t , 8 2 ( l 4 ) , 1952, p p . 350-4.  -  SNODGRASS, R.E., (1956) "Anatomy o f t h e Honey Bee", ( B o o k ) , Comstock, I t h a c a , 1956, Ch. 8, p p . 227-242. TCHISEVSKY, k.L., Acta. M e d i c a  (1940) " T S a i t e m e n t du rhumatisme aux a e r o i o n s S c a n d i n a v i c a , 104, 1940, p p . 561-577.  artificiels",  UVAROV, B.P., ( l 9 3 l ) " I n s e c t s and c l i m a t e " , T r a n s a c t i o n s o f t h e R o y a l E n t o m o l o g i c a l S o c i e t y o f London, J_9, 24 A p r . 1931, PP» 1-247. VERDU, R., (1955) " I o n o t e r a p i a a n t i r r e u m a t i c a " , L a S e m a m M e d i c a , 3 Nov. 1955, p p . 788-791. WEBER, H., (1954) " G r u n d r i s s d e r I n s e k t e n k u n d e " , V e r l a g , S t u t t g a r t , 3rd r e v i s e d e d i t i o n . WEIS-FOGH, T., (1949) "An a e r o d y n a m i c s e n s e r e g u l a t i n g f l i g h t i n l o c u s t s " , Nature, WELLINGTON, W.G.,  (Book), Gustav  Fischer  o r g a n s t i m u l a t i n g and 164, 1949, pp. 873-4.  ( l 9 5 7 ) "The s y n o p t i c a p p r o a c h  to studies of i n s e c t s  43  and climate", Annual Review of Entomology, 2j, 1957, pp. 143-162. WILLIAMS, CM., (1953) "Insect breathing", S c i e n t i f i c American, 188, Feb. 1953, PP. 28-32. WORDEN, J.L., and THOMPSON, J.R., (1956) "Air-ion concentration and the growth of c e l l s i n v i t r o " , The Anatomical Record, 124(2), Feb. 1956, p. 500. YAGLOU, CP., BENJAMIN, L . C , and BRANDT, A.D., (1933) "Physiological changes due to exposure to ionized a i r " , Journal of Heating, Piping, and A i r Conditioning, _5_, 1933, pp. 422-430.  Tritium source  600v  Beckett probe and guard ring  Ti  { =* \  i i  Ion current  Reversing switch  Electrometer  rrrj rtn  FIG. I  FIG. 2  Determination  of  ion current density  Ion current density from a  50 millicurie tritium  source as a function of distance and potential.  rf VTVMi 1,  it 71  Electrometer  Source  G  t  J  ;  Probe n 1 / 7 77  600v Electrometer  J  Electrometer  /7" 7 7  fTTl  VTVM  300v !  /7T7  FIG. 3  Method  of  measuring  the effect of  metal  grids between source and collector probe.  ¥6 L5T  V  £  Potentiol of  G  relative to source for various  4  distances to the probe x. FIG. 4  Currents produced by arrangement shown in FIG. 3 . V| fixed a t - 4 2 5 v , to  G, 3cm ,  V$ = -560v,  G, to G  2  z  source  I cm . The currents are a  function of the variables V between G  distance  2  and of x (distance  and the collector probe)  Fixed  cathode and  Movable  grid  plate  6.9 mm. O.D. Pinholder from miniature tube base 125" pin, .040" 5" glass rod,  FIG. 5  Diagram of 5734  0D.  .040" I.D.  transducer and  extension.  6v Battery  FIG. 6  Basic  bridge circuit for  transducer  FIG. 7  Method  of  Wax Pull  B  attaching insect.  jp+S cm vertical glass rod attached to transducer.  10 cm Direction of resultant force.  Vertical torsion wir<  N  3cm  -Aluminum  damping  vane  immersed in oil.  FIG. 8  View of torsion wire mounting shown in Plate 3.  Gloss rod extension  FIG. K)  Calibration  curves for transducer  FIG. II  Method of obtaining constant flow of  CO  Percent CO* FIG. 12.  C0  2  levels in the wind tunnel as a  pressure at the orifice.  function of  gas  To C0  C0  2  2  analyzer  and  -  air from blower.  FIG. 13  R)ints in the wind tunnel at which sampled. Analyzer intake  CC\  CO  a  levels were  1.6 in. from floor.  (%)  Orifice pressure  2  4  6  Time (min) after start of C 0 FIG. 14  Rote of increase of C 0  2  35 cm  H 0 2  8 2  flow.  at points shown in FIG. 13.  10  .52  0.0 FIG. 15  Sample  forward  0.2  force recording obtained from an  insect  flight  in the  stationary  0.4  apparatus. 0.6 Volts 0.8  1.0  1.2 1.5  Time  240 FIG. 16  Wing  beat  220  frequency record accompanying  FIG. 15.  200  180 VYing beat frequency (pa/sec) 160  min.) 10  Paper speed 15  20  25  I2  1  30  per hour.  Specimen No. 21 0  5  10  15  July 2 2 ,  1959.  20  25  Lob. temp. 27.5°C 30  35  0  5  10  Fed 15  6.0 mg. 2 0 % 20  sugar 25  solution 30  35  40  45  50  FIG.  17  (above)  Transformation graphs  shown  Voltage^*  FIG. 18 Pull  of in  versus  Voltage FIG. 15 Time  versus  Time  into plots.  (right)  changes  commercial  due insect  to the  presence  repellents.  of  two  BLOWER  REGULATED  J  GAS ANALYSER  b  r~| POWER SUPPLY DC AMPLIFIER  REPELLENT VAPORIZER  i T O O v DC  TRANSDUCER No.1  i  TRANSDUCER No. 2  o  BLOWER  CRO  DUALTRACE AUDIO  AUTOMATIC AIR S T R E A M SHUTTER  OSCLLATOR ELECTROMETER  A  _  4»B  OUT  HOv A C  IMPEDANCE MEASURING  POTENTIOMETER  I2»  sr"  CIRC.  AC R E L A Y  WING B E A T FREQUENCY RECORDER ELECTROMETER  B L O C K DIAGRAM O F FLIGHT A P P A R A T U S A N D  OC^)—T  AUTOMATIC  RECORDING  SYSTEM  D E T A I L E D  S C H E M A T I C  D I A G R A M  TABLE I Tabulations of duration normal c o n d i t i o n s  Specimen number  2 L  3 L  4 L  5 L  10 M  and under  Normal  of insect  under  ionization.  Positive  85.3 M i n 80.0 84.0 83.2+2.8 64.2 74.3 81.7 73.3+8.8  flight  Negative  81.3 Min  66.3 Min  87.3  105.7 86.5 82.2 90.0 90.8+6.9  104.3 77.3  94.0  48.3 56.8 61.7 58.3 48.-7 54.5 54.7+5.3  51.5 56.7  58.8  63.0  60.53  47.3 52.1  59.1 81.3 59.9+15.0 11 M  40.6 39.5 41.7  45.7 40.6+3.8 14 M  101.0  16 M  44.8 39.5 46.7 38. Ii 44.5  54.4 78.1  64.8  38.6 37.8  4T7T+3.8  35.0 3T7T  59.3  TABLE I  S p e c i m e n Number  18 M  19 M  Normal  (Continued)  Positive  54.6 38.3 54.0 49.0+9.2  Negative  56.1  34.0 39.2:  50.9 36.4  40.1+7.5 20 M  50.9  46.4  29.5 28.9  31.6 35.0 27.7  38.2 31.8+4.0 21 M  32.0 50.0 41..0+13  L indicates  Lucilia  sericata  M indicates  Muscina  stabulans  31.9  24.8  41.1  3 6..53  TABLE  II  Energies of f l i e s measured i n the f l i g h t apparatus under normal conditions and under ionization. (Arbitrary units proportional Specimen Number  to energy.)  Normal  Positive  Negative 67.7  10 M  73.9 67.4 131.4 64.8 84.4+10.0  85.6  11 M  78.7 90.0 56.5 73.5 88.2 54.0 73.5+15.4  84.2 88.4  16; IM  62.5 53.8 41.2 40.3 48.4 60.4 68.2 53.5+10.3  66.5 50.2  74.-9  19 M  50.3 48.8 53.8 67.2 55.2+8.4  66.1  71-6  20 L  76.7 55.2 106.1 69.2 69.8 82.9 76.6+17.3  79.5  67.4 61.6  21 M  68.9 73.2 71.1+3.4  77.2  TABLE II (Continued) Specimen Number 23 L  Normal 87.9 78.9 83.4+6.4  Positive 83.1  Negative 101.9  61 TABLE III Summary of results of ionization study  Time of f l i g h t Positive  Negative  Energy Output Positive  Negative  Within Mean + <y ( i . e . unchanged)  8  6  6  2  Deviation > M+0"  4  35  2  4  < M-C  3  1  0  1  > M+2'0~  1  2  0:  2  < M-2.0-  1  0  0  0  M+3<T  0  0'  0  0)  Outside  FLIGHT  APPARATUS and GRAPHICAL  RECORDERS  PULL & HORIZONTAL AC  VERTICAL TUBE from  SPECIMEN  BLOWER  INTAKE  FLUID DAMPIN IR S T R E A M  i r,  under  TRANSDUCER  AC  TRANSDUCER  TEST to  GAS  ANALYSER  SHUTTER  TORSION TORSION  NICHROME HEAD  PLAT  FLIGHT  APPARATUS  WIRE  HEATER  

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