The broad spectrum insecticide, acephate, neonicotinoid insecticides, acetamiprid, thiamethoxam, and imidacloprid, and other insecticides, λ-cyhalothrin, emamectin benzoate, indoxacarb, and spinosad were evaluated for their effects on the cotton aphid, Aphis gossypii, its entmopathogenic fungus, Neozygites fresenii, aphid parasitoids, lacewings, and coccinellids. Numbers of cotton aphids were significantly higher in plots treated with broad-spectrum insecticide than in untreated plots. Also, levels of both fungus-infected aphids and parasitized aphids were significantly higher in plots treated with broad-spectrum insecticide than in untreated plots. Numbers of lacewings and coccinellids were not significantly different between insecticide treated and untreated plots. Levels of fungus-infected aphids were lower in acetamiprid- treated plots than in other treatments. Aphid population levels were lower in acetamiprid and thiamethoxam treated plots than in dicrotophos and untreated plots. Numbers of cotton aphids in neonicotinoid plots were lower than in untreated plots for both dryland and irrigation fields. However, levels of fungus-infected aphids in neonicotinoid plots were lower than in untreated plots. Numbers of cotton aphids in λ-cyhalothrin, indoxacarb, and spinosad-treated plots were not significantly different from those in untreated plots. Levels of fungus-infected aphids, numbers of lacewings and coccinellids were not significantly different among insecticide treatments.
Population dynamics of the cotton aphid, its fungus, and other natural enemies were evaluated in Bt and conventional cotton in two locations. Numbers of aphids were not significantly different between Bt and conventional cotton. Different locations between Station I and Station II had different numbers of aphids and different levels of fungus-infected aphids. Levels of fungus-infected aphids, winged aphid populations, and fungus-infected winged aphids were not affected by cotton variety.