D3200: A bioassay method to test stem gall qasp Hemadas nubilipennis mortality to systemically delivered chemicals in blueberry bush shoots

Blueberry stem gall wasp (Hemadas nubilipennis) is a pest of high-bush blueberry and is a challenge to control with foliar applied insecticides, due to adult activity during bloom and larval development within the plant tissues. Insecticides delivered within plant tissues by the vascular system of the plant, known as systemics, were evaluated for control of blueberry stem gall wasp using single shoot bioassays and measuring larval mortality. Shoots containing one gall were administered either imidacloprid or flupyradifurone at 10%, 1%, 0.1%, and 0.01% dose within a floral pick. After five days galls were sliced open, and larvae were assessed for mortality. Additional shoots were used to determine mean active ingredient recovered from galls and leaves. Mean percentage of larval survival correlated negatively with active ingredient recovered. Imidacloprid and flupyradifurone were found to have the greatest potential for control of blueberry stem gall wasp at a 1% rate. This bioassay method can be used in the future to inform decisions on use of other systemics by evaluating larval mortality response to dose, and active ingredient recovered from gall tissues.