Effect of landscape on spotted wing Drosophila (Drosophila suzukii) infestation in raspberry

Drosophila suzukii is an emerging pest of soft-skinned fruit crops worldwide and sustainable pest management relies on understanding and predicting infestation risk. Previous studies have focused on D. suzukii’s host preference and fruit crop susceptibility to predict farm risk, while few studies have examined the relative role of landscape. The amount and quality of woodland and woodland edges surrounding a farm may be important for providing wild hosts such as common blackberry (Rubus spp.) and honeysuckle (Lonicera spp.). In this study, we examined the contribution of landscape composition and configuration to D. suzukii infestation risk, which we defined as the date of first infestation and overall severity of infestation. We collected broad- and local-scale landscape factors including quality of woodlands (presence and abundance of wild hosts) and quantity of total woodland and woodland edges. Over the 2013 growing season, we monitored D. suzukii across Southern Wisconsin at 18 raspberry farms that varied across a low to high woodland gradient with yeast-sugar traps placed in raspberries and woodlands. Date of first infestation was correlated with percent woodland (at 1.5km), with high woodland farms infested earlier in the season. Results on the relationship between landscape and infestation severity are forthcoming.  In 2014, the study will be expanded with collaborators in Michigan and Minnesota to understand if these patterns hold across the Upper Midwest. Study results will broaden our understanding on the effect of landscape on D. suzukii infestation in raspberry and will help growers make more informed decisions in their pest management.