Hessian Fly (Mayetiola destructor) Interaction with Seed Applied and Foliar Applied Insecticides

The Hessian fly, Mayetiola destructor (Say), is a common economically important pest of wheat throughout the southeastern US. This pest of wheat is multi-voltine, with generation number dependent on temperature. Management approaches rely on resistant wheat varieties, crop rotation, timely plantings, and insecticide treatments. Currently, no published economic thresholds based on egg counts have been developed for Hessian fly. The objectives of this research were to show the impacts of a common insecticide seed treatment and common foliar spray on Hessian fly in wheat and to develop a preliminary egg count threshold. Wheat was planted early and timely at two different eastern North Carolina locations. Treatments included untreated wheat seed, bimonthly foliar lambda-cyhalothrin, imidacloprid seed treatment, and imidacloprid seed treatment + bimonthly foliar lambda-cyhalothrin. Number of eggs present on leaves, number of larva, and the number of pupa in the plant were counted for the fall generation and the spring generation was eliminated through foliar sprays. A regression was used to run egg counts against larva, egg counts against pupa, and egg counts against yield to develop a preliminary threshold for management. Wheat treated with imidacloprid had fewer eggs, larva, and pupa compared to plots with other treatments.