Effect of cyhalothrin on field populations of the cotton aphid, Aphis gossypii glover, in the Texas High Plains

Cotton aphid, Aphis gossypii Glover, population densities in untreated cotton plots were compared with those in plots receiving one and two applications of cyhalothrin (Karate registered ) and one application of dicrotophos (Bidrin registered ). The cyhalothrin applications were timed to simulate typical treatment(s) for bollworm, Helicoverpa zea (Boddie), infestations and the dicrotophos application targeted beneficial arthropods. Rapid increases in aphid population densities occurred within 2 wk of cyhalothrin applications, resulting in significant yield reductions. Aphid numbers in dicrotophos treated plots were not significantly different from those in untreated plots on any sample date. Increases in aphid numbers did not appear to be due to reductions in predator populations, and predator populations appeared to increase only in response to increasing aphid populations.