Field evaluation of commercial plant extracts against Drosophila suzukii (Diptera: Drosophlidae) in raspberry

Abstract

ABSTRACTDrosophila suzukii (Matsumura) (Diptera: Drosophilidae) was detected in 2008 in southern Europe and North America and it has spread rapidly throughout the two continents mainly affecting thin-skinned berries and stone fruits which constitute an important, economic and social driver in these regions. This study analyzes the potential control ability of four commercial plant-derived extracts, namely Sophora flavescens (shrubby sophora), Cinnamomum zeylanicum (cinnamon), Capsicum frutescens (chili) and Allium sativum (garlic), against D. suzukii, under raspberry high tunnel field conditions. Extracts were applied in a randomized complete block design using spinosad as positive control. As expected, spinosad treatment resulted in a satisfactory control, reducing significantly the number of larvae and adults emerged from treated fruits even ten days after application. Sophora flavescens extract produced a significant reduction of 60.7% in emerged adults, with no reduction in the number of larvae, six days after application. In addition, garlic extract caused significant reduction in the mean number of larvae (over 50%) and emerged adults (over 48%) six days after application. These findings suggest that garlic and S. flavescens affect egg viability and/or larvae development. Tentative explanations about the variability of the results and possible benefits of repetitive treatments are discussed.