Evaluation of Dicyphus hesperus for biological control of sweet potato whitefly and potato psyllid on greenhouse tomato

The potato psyllid, Bactericera cockerelli Sulcer (Hemiptera: Psyllidae), and the sweetpotato whitefly, Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae), are major pests in tomato in the USA, Mexico, and Central America. Earlier research revealed that the mirid bug Dicyphus hesperus Athias-Henriot (Heteroptera: Miridae) has favorable rates of development and reproduction when reared on whitefly and psyllid and is able to provide good control of both pests on tomato in cage experiments. Consequently it could have potential as a biological control agent of these pests. Nevertheless, it has yet to be demonstrated that the addition of D. hesperus to existing biological control programmes improves management of these pests in commercial tomato greenhouses. In the present study, experiments were designed to evaluate D. hesperus as a predator of B. tabaci and B. cockerelli in tomato in large cages simulating commercial greenhouse conditions in two different cropping seasons (fall-winter and summer) in two subsequent experiments. In each season, a randomized complete block design was used with three replicates and two treatments: (1) No D. hesperus, receiving B. tabaci and B. cockerelli, and (2) D. hesperus, receiving B. tabaci and B. cockerelli as No D. hesperus plus D. hesperus. The predator established and reproduced well in the crop and also provided significant reduction of the whitefly and psyllid populations in both cropping seasons. In addition, no evidence of plant damage on either leaves or flower was observed, although a little fruit damage of presumably non-economic significance was recorded. Our results demonstrate that implementation of augmentative releases of D. hesperus would improve biologically-based management strategies in tomato and presumably help to increase adoption of such programmes in tomato in North America.