Flower thrips (Frankliniella tritici) and western flower thrips (Frankliniella occidentalis) prevalence and importance in southeastern blackberry production

Blackberry production has rapidly expanded in the southeastern United States, with acreage increasing in Georgia, North Carolina, and South Carolina. Along with this increase in production has come new pest management concerns. Growers have reported high numbers of thrips during bloom and early fruit development and have been concerned that these insects are reducing fruit set and damaging developing fruit. In 2008, we monitored thrips populations at 4 blackberry plantings in western North Carolina and 1 planting in eastern North Carolina. At 2 of these locations, we monitored populations through harvest. Thrips were monitored weekly using yellow sticky cards, blue sticky cards, and 3 cylindrical traps colored either yellow, light blue, or dark blue. At each location, flower samples were collected near each trap, followed by fruit samples as the season progressed. Plant samples were then compared to trap captures. Thrips collected in traps and from plant tissue were counted, and a subset of 30 individuals per sample were identified to species. Thrips populations fluctuated throughout the growing season and were comprised of primarily eastern flower thrips (EFT). A late season flight of western flower thrips (WFT) was observed at the season-long western North Carolina location. This suggests that EFT may be responsible for floral feeding, while WFT may be a potential contamination pest.