Variation in the laboratory susceptibility of turf-infesting white grubs (Coleoptera: Scarabaeidae) to biological, biorational and chemical control products

Abstract

White grubs are the most widespread and damaging pests in turfgrass habitats of the northeast USA, and their management is highly dependent on chemical pesticides. Because this complex includes at least eight species, opportunities for pest management would be enhanced by understanding how susceptibility to control products varies across taxa. The objective of this laboratory study was to measure variation in the susceptibility of four species to 18 biological, biorational and chemical insecticides used as curative controls. Across species, the most efficacious biological and chemical insecticide alternatives were Steinernema scarabaei and chlorpyrifos respectively. For biorational and chemical insecticides, the European chafer [Amphimallon majale (Razoumowsky)] was the least susceptible species. For biologicals, the Japanese beetle (Popillia japonica Newman) was the least susceptible. Considering all control products, the oriental beetle [Anomala orientalis (Waterhouse)] was the most susceptible. The magnitude of variation in susceptibility supports the idea that a single product will not reliably suppress populations of all taxa, and highlights the need for pest management practitioners to identify white grub species before intervention. This differential susceptibility could have broader consequences for grub management if a numerically dominant target species is more completely suppressed than a co-occurring species.