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Entomopathogenic Fungi

Entomopathogenic Fungi

Taxonomic placing: Fungi.

Common name: None.

Of the several hundred fungal species that were identified as causing insect diseases, about one hundred are specific to insects in terrestrial and aquatic habitats. Many fungal taxa contain entomopathogenic fungi, most being placed in the classes Zygomycetes [e.g. Entomophthora muscae (Cohn)Fresenius and Erynia [Zoophthora] radicans (Brefeld) Humber et al.) and Hyphomycetes [e.g. Beauveria bassiana (Balsamo) Vuillemin, Verticillium lecanii (Zimmermann) Viegas, Metarhizium anisopliae Metschnikoff) Sorokin and Nomuraea rileyi (Farlow) Samson. The host range may be limited to a single family (e.g. N. rileyi on Noctuidae), a single order (E. muscae on Diptera) or may be broad, including several orders (e.g. B. bassiana on Lepidoptera, Hemiptera and Coleoptera). Most entomopathogenic fungi consist of isolates that are specific to the insect taxon on which they were found or to closely related species.

Insect infection is by spores that contact the cuticle, germinate, and emit germ tubes which penetrate the cuticle and invade the body. The pathogen circulates in the haemolymph as protoplasts, hyphal bodies and/or hyphae, colonizes various organs (sometimes aided by a secreted toxin), and eventually kills the host. The hyphae then protrude from the cadaver’s cuticle and form spores that infect healthy insects. Spore germination on the host (during infection), and hyphal growth along with sporulation on the cadaver, occur mostly at night when the relative humidity exceeds 90% and temperatures are moderate (e.g. 18-20°C). Solar radiation is lethal to these processes. In the last decade several commercial formulations of entomopathogenic fungi (Green Muscle of M. anisopliae, Naturalist®L and Mycotrol® of B. bassiana, and Mycotal and Vertalec of V. lecanii) were developed and used for pest control in greenhouses and in the field. Other important fungi, such as E. muscae and E. radicans, which have fastidious growth requirements and complicated life cycles, have yet not been developed commercially.

Over forty species of entomopathogenic fungi were found in Israel.

REFERENCES

Ben-Ze’ev, I.S. 1993. Check-list of fungi pathogenic to insects and mites in Israel, updated through 1992. Phytoparasitica 21: 213-237.

Butt, T.M., Jackson, C. and Magen, N. 2001. Fungi as Biocontrol Agents, Progress, Problems and Potential. CABI Publishing.

Lacey, L.A., Grzywacz, D., Shapiro-Ilan, D.I., Frutos, R., Brownbridge, M. and Goettel, M.S. 2015. Insect pathogens as biological control agents: Back to the future. Journal of Invertebrate Pathology 132: 1–41.

Samson, R.A., Evans, H.C. and Latge, J-P. 1988. Atlas of Entomopathogenic Fungi. Springer-Verlag, Berlin.

van der Geest, L.P.S. and Bruin, J. 2008. Diseases of mites and ticks: from basic pathology to microbial control - an introduction. Experimental and Applied Acarology 46: 3-6.

Dr. Aviva Uziel. E-mail: uziel@agri.huji.ac.il

Website:

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