Survey for spotted-wing drosophila (Diptera: Drosophilidae) in the five-county nursery production region of middle Tennessee, USA

Abstract

Through global trade, spotted-wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), a native of Southeast Asia, has spread to at least 3 other continents since 2008. Initial reports of the fly in new regions often are associated with damage in agriculture fields, but the fly may be present in the landscape for years before populations reach a level at which they become a pest in fruit production. In 2012, spotted wing drosophila was reported in blueberry fields in eastern Tennessee, USA, for the first time. In order to determine whether the fly was established in middle Tennessee, we conducted landscape surveys over 2 yr in the middle of the state's ornamental nursery industry where many fruit and ornamental hosts of the fly are grown. Red and yellow colored traps baited with yeast solution were placed in 17 locations of the 5-county nursery production region of middle Tennessee. Traps were monitored weekly for 8 wk in 2013 and 9 wk in 2014. Flies were caught at all 17 locations in 2013 and 16 of 17 locations in 2014. First activity was delayed 3 wk and total captures were 77% lower in 2014 relative to the previous year, likely due to high mortality of overwintering flies resulting from unusually cold winter temperatures in the region. No statistical differences were detected between trap colors in the landscape or between total captures of each sex, despite a trend for more female than male captures by the end of the season. Beginning Feb 2014, we also sampled weekly from a single yellow monitoring trap suspended within a plot of mixed-species dogwood trees (Cornus spp.; Caryophyllales: Cornaceae) for nearly 1 yr. Adult D. suzukii consistently were caught from late Jul until mid-Dec when the first frost occurred. Our surveys confirm that spotted wing drosophila is well established in the middle Tennessee nursery production region, despite no concurrent reports of damage by local small-fruit producers in the region.