Effects of aerial applications of cypermethrin and demeton-S-methyl on nontarget arthropods of wheat.

Cypermethrin (Ripcord) and demeton-S-methyl (Duratox) were each applied to large fields of winter wheat by fixed-wing aircraft. The numbers of soil surface- and foliar-dwelling arthropods were estimated at intervals before and after treatment in both the treated and an untreated control field, using pitfall traps and a D-Vac suction sampler. Cereal aphids were the major group of phytophagous insects collected from all of the trial sites. Both compounds caused an initial decline in their numbers immediately after spraying but a significant "resurgence" in aphid populations was observed in the demeton-S-methyl-treated field towards the end of the study. The major groups of entomophagous arthropods collected from the fields were Carabidae, Staphylinidae, Linyphiidae, Empididae, and Braconidae. With the exception of the effects of cypermethrin on linyphiids and demeton-S-methyl on empids, both of the treatments had only minor, short-lived effects on these entomophages. Neither of the compounds had any significant, long-term effects on general feeding (e.g., detritivorous) arthropods.