Evaluation of emergence traps for monitoring blueberry gall midge (Diptera: Cecidomyiidae) adults and within field distribution of midge infestation.

The blueberry gall midge, Dasineura oxycoccana (Johnson) (Diptera: Cecidomyiidae), is a key pest of rabbiteye blueberry, Vaccinium virgatum Aiton, in the southeastern United States, but it has not been studied extensively and little is known about its ecology and management. Studies were conducted to develop an improved method for monitoring D. oxycoccana adults and to determine the within-field distribution of infestation. Four emergence traps were evaluated in an organic rabbiteye blueberry planting for their effectiveness in capturing D. oxycoccana adults early in the season. These traps included a jar trap, wheat blossom midge trap, petri dish trap, and bucket trap. The petri dish and bucket traps captured the highest numbers of adults in 2007 and 2008, respectively. Both traps had a clear plastic panel coated with adhesive. Adult midges emerging from the soil beneath the traps were caught in the adhesive as they flew up toward the light. Emergence traps are useful for detecting the presence of adults early in the season before larval infestation is apparent in the flower buds. To determine the pattern of midge infestation, flower buds were collected weekly from January to March in 2006 from rabbiteye blueberry plants located in a plot at the southwest border of an existing blueberry planting. There were no differences found in the number of larvae collected from various distances within blueberry rows. However, when flower buds were collected from an isolated rabbiteye plot in 2007 and 2008, D. oxycoccana infestation was not uniform. In both years, the southern border row had a significantly higher number of midge larvae per bud compared with the other rows.