PREDATORS FEEDING ON THE COLORADO POTATO BEETLE IN INSECTICIDE-FREE PLOTS AND INSECTICIDE-TREATED COMMERCIAL POTATO FIELDS IN EASTERN NORTH-CAROLINA

Field studies in insecticide-free research plots and insecticide-treat ed commercial potato fields were conducted to determine the identity a nd seasonal abundance of the predators feeding on the Colorado potato beetle, Leptinotarsa decemlineata (Say) in eastern North Carolina, Tax a were classified as predaceous on Colorado potato beetle eggs or larv ae only if they were observed to feed on them in the field or to readi ly accept and survive for a prolonged period on a diet of eggs and sma ll larvae in laboratory studies. Excluding soil arthropods, which were not sampled, Colorado potato beetle eggs and larvae were by far the m ost abundant prey available in potato fields during this study, The co ccinellid Coleomegilla maculate (DeGeer) was the most abundant predato r but its abundance varied independently of prey abundance. In additio n, 13 insect genera, at least three spider families, one phalangid, an d one mite species were found to prey on the Colorado potato beetle. P rior to the application of carbofuran to commercial potato fields for control of the European corn borer (Ostrinia nubilalis Hubner) and Col orado potato beetle, dynamics and composition of the predator communit ies were generally similar to those in the much smaller untreated rese arch plantings. Although carbofuran applications always suppressed or eliminated the predator population, predators recolonized the commerci al fields within 1 to 2 weeks following its application. (C) 1996 Acad emic Press, Inc.