Effects of Five Granular Insecticides on the Abundance of Selected Arthropod Pests and Predators in Peanut Fields

Abstract

The effects on nontarget arthropods of five granular insecticides applied at flowering time to control the lesser cornstalk borer, Elasmopalpus lignosellus (Zeller), were compared in a 2-yr field study in conventionally planted and tilled ‘Sunrunner’ peanuts. Insecticides used were chlorpyrifos 15 G (15% granular), ethoprop 15 G, fonophos 10 G, Fortress 10 G, terbufos 15 G, and an untreated control. Beat sheets were used to sample weekly for arthropods inhabiting the canopy, and pitfall traps were used to sample for epigaeic (soil-surface dwelling) arthropods. Samples were taken for at least 5 wk after treatment. The applications of granular insecticides had very transitory effects on populations of secondary pests such as the com earworm, Helicoverpa zea (Boddie), and fall amlywoml, Spodoptera frugiperda (J. E. Smith) and no effect on populations of predaceous hemipterans. No consistent evidence of effects on secondary pests was noted. Abundance of three of the four groups of epigaeic predators that were monitored declined in some of the treated plots for as long as 1 mo. This underscores the need for timely applications of granular insecticides based on scouting.