D3038: Nut factors driving abundance and ovipositional preference of the hazelnut weevil (Curculio obtusus) in hybrid hazelnut

The hazelnut weevil, Curculio obtusus (Blanchard) (Coleoptera: Curculionidae), is native to North America and associated with endemic American (Corylus americana Marshall) and Eastern beaked (Corylus cornuta var. californica Marshall) hazels (Fagales: Betulaceae). Recently hybridized hazels, C. americana × C. avellana L. from Europe, have been developed for production of hazelnuts in the Midwestern US and Canada and C. obtusus is suspected to pose a threat to the economic stability of this new crop. Little is known about the ecology of C. obtusus. The purpose of this study was to study the seasonal phenology of adults and their oviposition in hybrid hazelnut plantings in the Upper Midwest in order to inform future management should it become necessary. We sampled pairs of six hybrid hazel genotypes weekly via beat-sheet sampling from May through July at two field locations in Minnesota. Female C. obtusus were dissected to count the number of mature eggs contained in ovarian tubules. We also measured hazelnut characteristics such as in-shell nut volume, shell thickness, and hazelnut cluster size weekly. Results will be presented in person. This work will form a baseline for development of integrated pest management plans for C. obtusus in the burgeoning hybrid hazelnut industry.