Spotted Wing Drosophila Prefer Low Hanging Fruit:Insights into Foraging Behavior and Management

Spotted wing drosophila is an invasive insect that attacks ripe, small fruit such as raspberries, blackberries and blueberries. Little was known about its foraging ecology. Here we evaluated adult alightment and egglaying preference within and among raspberry plants using sentinel Tangletrap-coated and clean raspberry fruit, respectively, positioned within the exterior and interior plant canopy at four different heights and conducted in field cages using sexually matureadults. Alightment of adults on Tangle-trap-coated fruit indicated a preference for fruit positioned at lower heights and/or interior locations based on significantly greater numbers being captured on sentinel sticky-coated berries at the two lowest heights. Oviposition in clean raspberry fruit also yielded a similar pattern. In mark-release-recapture studies conducted in the field, spotted wing drosophila prefer sentinel sticky fruit positioned on exterior rows as they alighted on these berries in significantly greater numbers than fruit at in the central portion of the plot. Likewise, in field trials with wild fly populations, infestations were significantly greater in edge rows compared with interior rows. Collectively, our results suggest that monitoring and behaviorally based management strategies may be more effective if they target adults foraging in the lower canopy of small fruit plants located on the crop perimeter.