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Aspects of the biology of entomogenous fungi and their associations with arthropods Jovel Ayala, Eduardo Méliton


I investigated several aspects of the biology of entomogenous fungi (mostly Clavicipitaceae with few species of Hypocreaceae). My primary motive in this research was to gain an understanding of the interactions between entomogenous fungi and arthropods. My study included field collections and identification of entomogenous fungi from BC and a few collections from Peru and Idaho. I addressed some aspects of the interactions among arthropods and fungi, life histories of fungi under laboratory conditions, and observations of chemical changes of fungi growing in the presence of heavy metals. About fifty entomogenous fungi were collected in the province, mainly as anamorphs, but this permitted isolation and cultivation of many species. Of special interest is a small group of fungi parasitic on spiders some of which may be new records for western Canada. Interactions of entomogenous fungi and heavy metals yielded a cerebroside not detected, or known to be produced, in the absence of heavy metals. This compound showed antibiotic activity against Staphylococcus aureus. The induction of this cerebroside by exposure to copper also is a promising approach to obtaining new drugs, or to increase the yield of selected compounds, from these organisms. The biological activities of other extracts were assessed, demonstrating additional compounds of interest (e.g., antiviral, antibacterial, phototoxic and antifungal substances). Cultures grown on substances rich in oils and proteins (nuts and seeds) appeared to induce development beyond the anamorph stage to early teleomorph form. No perithecia developed although large synnemata and relatively bright pigmentation were observed. The ability to induce complete development of ascocarps would be of laboratory interest in the possible production of substances from wild ascocarps. Cultures obtained in this study will be deposited in the Canadian National Culture Collection, Ottawa, in the Canadian Culture Collection (UBC). Further research remains necessary to fully understand the relationship between teleomorph and anamorph stages of entomogenous fungi, their nutritional requirements, for the production of teleomorph stages under laboratory conditions, and particularly to establish systems that may allow a chemical exploration for new drugs. The preliminary studies of anti-arthropod activity by entomogenous fungi were partially successful in controlling a variety of laboratory-reared and naturally growing arthropods. The production of bio-pesticides is currently of great interest because of the problems with chemical pesticides and environmental pollution. Gaining a better understanding of the biology of these organisms will allow us to develop new genetic strains of species for both biopesticides and biosynthetic applications. Both kinds of substances can contribute to maintain the health and equilibrium of the coastal temperate rainforest of the Pacific Northwest.

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