Infestation of Wild Fruit by<i>Drosophila suzukii</i>Surrounding Maine Wild Blueberry Fields¹

Abstract

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) is an invasive vinegar fly that attacks a large variety of soft fruits including wild blueberries in Maine. Wild blueberry fields in Maine are commonly surrounded by woodland edges that contain wild fruit. These edges are important refugia as they provide the fly with needed shade and moisture during the hottest parts of the day. The wild fruit in these wooded edges are also potential alternative hosts for D. suzukii. We surveyed wild fruit along blueberry fields to determine the types of fruit present and measured D. suzukii infestation levels in surveyed fruit. We also measured the number of adult D. suzukii along field edges and the level of infestation in the wild blueberry crop. Drosophila suzukii was found in nine out of seventeen surveyed wild fruit species along field edges. Our results suggest a correlation between wild fruit infestation levels and adult fly densities in the crop fields. Blueberry fields with higher levels of wild fruit infestation also showed higher levels of adult D. suzukii trap captures in the commercial blueberry fields. These wild fruit hosts may allow D. suzukii to increase its population abundance prior to moving into commercial blueberry fields.