Biological Control Potential and Drawbacks of Three Zoophytophagous Mirid Predators against Bemisia tabaci in the United States

SIMPLE SUMMARY: The silverleaf whitefly, Bemisia tabaci, is a serious economic pest of tomatoes, particularly as this insect can carry devastating plant diseases. Growers currently rely on costly insecticides and biocontrol agents may offer a viable alternative in the integrated pest management of tomatoes. We studied one established and two native omnivorous plant bugs’ (mirids) ability to control whiteflies, whether they damaged tomato plants, and their ability to persist in the crop. Established biocontrol agents have advantages as they typically have little impact on non-target native species, they have adapted to the local environment and are less expensive than importing and testing exotic agents. In field cage studies, all three species controlled whiteflies. However, the damage the mirids caused to tomato plants varied greatly. We also tested whether an alternate host plant, sesame, could increase mirid numbers and reduce plant damage. These experiments showed that the benefits of sesame varied among the mirid species. Although not all established generalist mirids would be suited for use as biocontrol agents, this study showed that two of USA’s mirid species could be immediately available to help manage existing and future invasive pests of tomato. ABSTRACT: Miridae (Hemiptera) of the tribe Dicyphini are important zoophytophagous predators use to control pest arthropods in vegetable crops. However, the risk that their herbivory may cause economic damage could hinder their application as useful biocontrol agents and may limit the likelihood they would meet regulatory requirements for importation. We conducted field cage studies to assess the predation capacity and tomato plant damage of three mirid species established in south USA, a known biocontrol agent (Nesidiocoris tenuis), and two native species (Macrolophus praeclarus and Engytatus modestus). All three species significantly reduced the number of whiteflies (Bemisia tabaci) on tomato plants compared to tomato plants without mirids. More damage, evaluated as the number of necrotic rings, was observed on tomato plants with E. modestus and N. tenuis compared to M. praeclarus. In our experiments that included sesame plants (Sesamum indicum) with tomato plants, mirid numbers increased despite a low number of prey, thus showing a benefit of the plant-feeding habit of these predators. USA’s established mirids may therefore prove to be immediately available biological agents for the management of present and future tomato pests.