Spotted cucumber beetle/southern corn rootworm: profile of a polyphagous native pest

Abstract

Spotted cucumber beetle, Diabrotica undecimpunctata (Coleoptera: Chrysomelidae), a North American native leaf beetle species also known as southern corn rootworm (SCRW), is a polyphagous pest of various crops including cucurbits (Cucurbitaceae), corn (Zea mays), soybeans (Glycine max), snap beans (Phaseolus vulgaris), peanut (Arachis hypogaea), and sweetpotato (Ipomoea batatas). Larvae are below-ground pests of corn, sorghum (Sorghum spp.), peanut, and sweetpotato. Adult damage impacts cucurbits by damage to seedlings and fruit and transmission of bacterial wilt (causal agent Erwinia tracheiphila) by eastern populations. Adult feeding also damages fresh market beans and occasionally leafy and fruiting vegetables. Damage on many other crops such as field soybeans, dry beans, and sorghum, is often cosmetic and/or inconsequential. Adults overwinter in mild climates and spread seasonally northward, with multiple generations and populations increasing into the late summer. Diverse natural enemies attack all stages, but their ecology and impact are poorly known, particularly below ground. A female-produced sex pheromone and floral volatiles are known attractants, and cucurbitacins (bitter phytochemicals) are feeding stimulants, offering potential selective behavioral control. Management practices are directed against pest complexes, including other below- and above-ground pests, depending on the crop. Chemical controls are soil-applied for protection from root-feeding larvae, systemic seed treatments for early-state crop feeding, and broadcast application in fruiting cucurbits and beans. Action thresholds and monitoring are not well developed. Cultural controls include field and cultivar choice, row covers in high-value crops, and available crop resistance. The wide host range, abundance, and mobility of adults make prediction and monitoring challenging.