Influence of fungicides on development of an entomopathogenic fungus (Zygomycetes: Neozygitaceae) in the cotton aphid (Homoptera: Aphididae)

Smith, M.T.; Hardee, D.D.

Influence of fungicides on development of an entomopathogenic fungus (Zygomycetes: Neozygitaceae) in the cotton aphid (Homoptera: Aphididae)

1996

Smith, M.T. | Hardee, D.D.

Fungicides used commercially for control of cotton seedling diseases were evaluated under field conditions during a 3-yr period for their effects on the prevalence of the entomopathogenic fungus Neozygites fresenii (Nowakowski) Batko in the cotton aphid, Aphis gossypii Glover. The susceptibility of N. fresenii to the fungicides varied. Carboxin significantly reduced N. fresenii prevalence during the early season. Furthermore, A. gossypii population levels were significantly greater during the 1993 field test in plots treated with carboxin. In some cases etridiazole and metalaxyl also significantly reduced N. fresenii prevalence during the early season. Conversely, N. fresenii prevalence was generally equivalent to or greater in the fungicide-treated plots than in the control plots during the late season. Although numerous biotic and abiotic factors (that is, environmental or artificial or both) also influence fungal prevalence in field situations, this appears to be the 1st demonstration of reduced entomopathogenic fungal prevalence caused by the application of a granular fungicide at planting. Biological and cultural implications are discussed.

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