Effects of lure dose on efficacy of pheromone traps for monitoring Argyrotaenia citrana (Lepidoptera: Tortricidae) in California apple orchards

This study tested lowering the lure dose of Argyrotaenia citrana (Fernald) pheromone to improve the accuracy of the traps as indicators of larval density (and subsequent fruit damage) within coastal California apple orchards. Different doses of pheromone ranging from 1 to 0.001 mg were tested in commercial apple orchards in 1994 and 1995. Mean weekly trap catches were significantly higher in higher dose traps. However, the proportion of moths caught in higher dose traps versus lower dose traps remained fairly constant within each orchard, suggesting that lower dose traps were attracting moths from the same regional pool of moths as the higher dose traps. No statistically significant relationships were detected between average weekly moth catches using each of the 4 lure doses and A. citrana larval counts in 1995. These results suggest that lowering lure dose will not improve the accuracy of pheromone traps as predictors of A. citrana larval density. The lack of correlations between larval densities and male moth counts is discussed relative to the need to monitor female flight activity.