Efficacy of Selected Granular Insecticides in Soil in ‘Florunner’ Peanut Fields to Larvae of Lesser Cornstalk Borer (Lepidoptera: Pyralidae)

Abstract

Survival of lesser cornstalk borer, Elasmopalpus lignose/lus (Zeller), larvae in soil from conventionally tilled and planted ‘Florunner’ peanut, Arachis hypogaea L., fields treated with selected granular insecticides at pegging was evaluated in Alabama and Florida in 1988 and 1989. Insecticides tested were chlorpyrifos, fonofos, butathiofos, ethoprop, tefluthrin, terbufos, and Fortress (O, O-diethyl O-1,2,2,2,2, tetrachlorethyl phosphorothioate). Survival of lesser cornstalk borer larvae in untreated soil was 84.8 ± 2.1% (x ± SEM). Chlorpyrifos and fonofos significantly reduced larval survival compared with larval survival in soil from untreated plots 5-14 d after application in all four experiments. They were also the only insecticides that reduced larval survival at 25-28 d after application in three of the four experiments. Chlorpyrifos was the only insecticide that was effective for> 14 d in all four experiments. The length of effectiveness of chlorpyrifos, as indicated by laboratory bioassay, ranged from 19 to 67 d after treatment.