Landscape features determining the occurrence of Rhagoletis mendax (Diptera: Tephritidae) flies in blueberries

Non-crop areas surrounding farms can support pest populations if they provide overwintering habitats or alternative hosts for them to feed and/or mate. Here we tested the hypothesis that a native North American pest of highbush blueberry, the blueberry maggot fly (Rhagoletis mendax Curran) is more abundant near forest habitats. For this, we monitored R. mendax adult occurrence using a trapping network across multiple farms and years (2009-2012) in New Jersey (USA), and then performed geospatial analysis on these data to determine whether traps in blueberry fields near forest habitats experience higher R. mendax adult captures than others. In addition, we conducted mark-release-recapture studies to determine the distance R. mendax flies can move into blueberry fields. Our results reveal that proximity to forest habitats positively affects R. mendax adult occurrence on traps. However, the type of forest was critical such that presence of flies on traps declined with increasing distance from upland forest while distance from wetland forest had no effect. We also showed that R. mendax flies can disperse up to 76 m into a blueberry field from adjacent wooded habitat within 48 h. In sum, our study identified landscape features important for R. mendax occurrence in blueberry fields, which can improve sampling methods and the development of precision-based pest management programs. Based on our findings, monitoring efforts and insecticide applications for R. mendax should be targeted mainly to fields close to upland forest and directed to the field borders within distances of less than 80 m from field edges.