Evaluation of mass trapping as a management strategy for grape berry moth

Grape berry moth, Paralobesia viteana (Clemens), is a major pest of vineyards in eastern North America. Control of cluster infestations by grape berry moth larvae is a major driver of insecticide applications to grapes in this region, so there is a need to identify effective alternative management strategies for this pest. Mass trapping is a potential non-pesticide approach for reducing grape berry moth damage, but it has not been well tested for this insect. In May 2015, a field experiment was performed to test the effectiveness of mass trapping as a management tool. We aimed to determine (1) whether mass trapping at vineyard borders reduces grape berry moth infestation, (2) whether moth capture is related to damage severity, and (3) whether the distribution of damage is affected by mass trapping treatments. Four different trap density treatments were applied to vineyard border areas at each farm in a randomized complete block design. An additional pheromone monitoring trap was deployed at the border and interior of each vineyard to measure male flight activity. Comparison of preharvest damage samples using ANOVA did not detect significant differences between mass trapping treatments. In treatments with higher trap density, more male moths were trapped; however, similar levels of infestation were observed between treatments. Linear regression of grape berry moth damage on distance from the vineyard border showed that the relationship between these variables was similar in vineyards that received different treatments. We conclude that mass trapping does not significantly reduce grape berry moth damage in vineyards.