UBC Theses and Dissertations
Effects of certain insecticides on the biotic potential of Epitrix tuberis Gentner (Coleoptera: Chrysomelidae) Finlayson, Douglas Gordon
Investigations on biology and control of the tuber flea beetle Epitrix tuberis Gentner, were conducted at Merritt, B.C. in 1948. Although some insecticides under examination were commercially effective, there were indications that tuber damage was greater than expected in proportion to the control produced. The possibilities of a sub-lethal dosage and its effect on the potential of this species necessitated additional experiments in the laboratory. Cultures were fed on potato leaves dipped in solutions of the following insecticides: 0.005% D.D.T. 0.005% Toxaphene 0.005% D.D.T./O.3% Calcium Arsenate 0.3% Calcium Arsenate Since the effects of insecticides on both mortality and oviposition were under observation these treatments were introduced after the female of a mated pair of beetles had oviposited for one day. One hundred percent mortality was produced by each insecticide in 48 hours with a marked decrease in oviposition below the normal. However, the fact that oviposition occurred at all is the suspected reason that tuber damage was greater than expected from the control produced. This, accompanied by a mistimed application of the insecticide could well account for a heavy larval infestation of potato tubers although achieving excellent control of the adults. Contact treatments were carried out with the above insecticides and similar results were obtained which further substantiated the supposition that oviposition commenced before the application of the chemicals.