The invasive exotic spotted wing drosophila (SWD, Drosophila suzukii) has become the leading pest of berries and stone fruit nationwide. Inaccessible life stages (egg to pupa inside fruit), polyphagous diet, low predation and parasitism by indigenous beneficials, and rapid lifecycle (13 days) make SWD difficult to control, forcing growers to intensify pesticide use. EntrustTM (spinosyn) and conventional pesticides are effective, but SWD can evolve pesticide resistance.

This project laid the groundwork for effective, regionally tailored, organic IPM based on enhanced understanding of the biology of SWD and its natural enemies. Researchers tested behavioral, cultural, physical, biological, and chemical tactics.

Findings include:

• Food-grade gum traps with volatile attractants reduced berry damage by half.
• Spraying crops with a wax-based horticultural cuticle supplement reduced SWD damage in blueberry and cherry by 45-95% in field trials in OR.
• Attract-and-kill products like HOOK-SWD (attractants + spinosyn) reduced SWD by 50-90% in blueberry (NJ) and raspberry (CA) but were less effective at high SWD levels.
• Temperatures >85°F curtail SWD reproduction. Pruning, weed mat, and drip (vs. sprinkler) irrigation for hotter microclimates reduced SWD damage in some trials.
• Non-crop hosts like wild blackberry and pokeweed can harbor SWD.
• Generalist predators consume SWD pupae if pesticide use is low.
• The exotic parasitoid wasp Ganaspis brasiliensis, shows promise on SWD and has been cleared by APHIS for field release.
• Native parasitoids may evolve virulence (efficacy) against SWD.
• Hummingbirds reduced SWD trap counts and raspberry fruit damage in NY.
• Spinosyn controlled SWD in most trials, but highly spinosyn-resistant populations have arisen in CA, and some resistance has been reported in GA.
• Exclusion netting reduced SWD damage and improved net returns for organic high-tunnel raspberries in MN.