INFLUENCE OF FUNGICIDES ON DEVELOPMENT OF AN ENTOMOPATHOGENIC FUNGUS (ZYGOMYCETES, NEOZYGITACEAE) IN THE COTTON APHID (HOMOPTERA, APHIDIDAE)

Fungicides used commercially for control of cotton seedling diseases w ere evaluated under field conditions during a 3-yr period for their ef fects on the prevalence of the entomopathogenic fungus Neozygites fres enii (Nowakowski) Batko in the cotton aphid, Aphis gossypii Clover The susceptibility of N. fresenii to the fungicides varied. Carboxin sign ificantly reduced N. fresenii prevalence during the early season. Furt hermore, A. gossypii population levels were significantly greater duri ng the 1993 field test in plots treated with carboxin. In some cases e tridiazole and metalaxyl also significantly reduced N. fresenii preval ence during the early season. Conversely, N. fresenii prevalence was g enerally 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) als o influence fungal prevalence in field situations, this appears to be the Ist demonstration of reduced entomopathogenic fungal prevalence ca used by the application of a granular fungicide at planting. Biologica l and cultural implications are discussed.