Capture of Males of the Light Brown Apple Moth, Epiphyas postvittana (Walker), in Pheromone-Baited Delta Traps of Differing Size and Design

The light brown apple moth, Epiphyas postvittana (Walker), is a polyphagous pest first reported in California in 2006. State and federal agencies responded by initiating a large-scale trapping program to monitor its spread and population dynamics. The purpose of this study was to compare the trap catch between two delta traps differing in size and design. Both trap types were baited with female pheromone and trapped E. postvittana males on a sticky base. This insert was 121 cm2 in the smaller Jackson traps compared to 360 cm2 in the larger Scentry LP traps. In addition, the ends of the trap floor were folded upward (forming barriers) in the Scentry LP traps, whereas Jackson traps lacked such barriers. Working in San Francisco, I established 13 pairs of traps (one Jackson and one Scentry LP trap) and serviced them weekly during two separate 6-week intervals (June-August and September-October, 2008, respectively). Data for the Scentry LP traps showed that significantly more males were caught in September-October than in June-August, whereas captures in the Jackson traps were not significantly different between the early and late sampling periods. Correspondingly, numbers of males captured per trap per day were not statistically different between the two trap types in the early period but were significantly higher for the Scentry LP traps than the Jackson traps in the later period. Implications of these results for the ongoing detection and survey program are discussed