Potential Nontarget Effects of Metarhizium anisopliae (Deuteromycetes) Used for Biological Control of Ticks (Acari: Ixodidae)

• Published in: Environmental entomology 2002-12, Vol.31 (6), p.1191-1196
• Main Authors: Ginsberg, Howard S, Lebrun, Roger A, Heyer, Klaus, Zhioua, Elyes
• Format: Article
• Language: English
• Subjects: Acheta domesticus; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; BIOLOGICAL CONTROL; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on protozoa and invertebrates; Fundamental and applied biological sciences. Psychology; Hippodamia convergens; Medically important nuisances and vectors, pests of stored products and materials: population survey and control; Metarhizium anisopliae; nontarget effects; Oncopeltus fasciatus; pathogenicity; Vectors. Intermediate hosts
• ISSN: 0046-225X; 1938-2936
• DOI: 10.1603/0046-225X-31.6.1191

The potential for nontarget effects of the entomopathogenic fungus Metarhizium anisopliae (Metschnikoff) Sorokin, when used for biological control of ticks, was assessed in laboratory trials. Fungal pathogenicity was studied against convergent ladybird beetles, Hippodamia convergens Guérin-Méneville, house crickets, Acheta domesticus (L.), and the milkweed bugs Oncopeltus fasciatus (Dallas). Fungal spores applied with a spray tower produced significant mortality in H. convergens and A. domesticus, but effects on O. fasciatus were marginal. Placing treated insects with untreated individuals resulted in mortality from horizontal transmission to untreated beetles and crickets, but not milkweed bugs. Spread of fungal infection in the beetles resulted in mortality on days 4–10 after treatment, while in crickets mortality was on day 2 after treatment, suggesting different levels of pathogenicity and possibly different modes of transmission. Therefore, M. anisopliae varies in pathogenicity to different insects. Inundative applications can potentially affect nontarget species, but M. anisopliae is already widely distributed in North America, so applications for tick control generally would not introduce a novel pathogen into the environment. Pathogenicity in lab trials does not, by itself, demonstrate activity under natural conditions, so field trials are needed to confirm these results and to assess methods to minimize nontarget exposure.