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Cornell Fruit Resources

Resources for Commercial Growers

Monitoring

Spotted Wing Drosophila

Genus species: Drosophila suzukii

Simple traps can be made to monitor for this very important pest — research on SWD traps and baits has shown that the commercially available traps and lures by Scentry and Trece work as effectively as the home-made whole wheat dough trap. Traps baited with an apple cider vinegar drowning solution plus an ampule containing a fermenting whole wheat dough bait floating in the cider vinegar have proven successful in capturing adult SWD. Traps should be checked once per week, adding fresh vinegar drowning solution and fresh bait. For easier sorting through trap contents to find SWD, check traps daily.

There is a trap network run by Extension personnel across New York State who are monitoring SWD in fruit plantings. The results of their findings are posted on the Spotted Wing Drosophila blog and a distribution map is generated from the SWD trap network. The SWD findings by the network can provide early warning of SDW arrivals in NY.

Another outcome of monitoring SWD with traps is to gain a perspective on the effectiveness of insecticide treatments in eliminating SWD from a planting, though research to validate this is lacking.

Fruit can be inspected for evidence of larval feeding. Small holes in berries made by the larvae may leak juice when the berry is gently squeezed; this is especially diagnostic on blueberry. Fruit with multiple drupes, such as raspberry may be so fragile as to not lend itself to this type of examination. Infested red raspberry fruit may leave a red juice stain on the berry receptacle when the fruit is picked. Raspberries may also leak juice onto foliage. Fruit with small indents or bruises where the berry surface appears to have flattened or deflated may be infested.

Salt Floatation to find larvae. Immersing fruit in a solution of 1 Tbsp. (14.8 cc) table salt per 1 cup (236.6 ml) water, will cause larvae to emerge from fruit. An effective sample size being used for checking fruit for infestation on large-scale commercial farms is at least 100 fruit per block per harvest. Suggested methods were adapted for NY growers in Guidelines for Checking Fruit for SWD Larvae in the Field (pdf).

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