Captures of Stenoma catenifer (Lepidoptera: Depressariidae) are influenced by pheromone trap density in Hass avocado orchards

Stenoma catenifer Walsingham is a quarantine pest of avocado. Therefore, its detection in avocado-growing regions of Mexico that had been desig-nated pest-free can halt national and international trade. One option for monitoring S. catenifer is the use of synthetic sex pheromone traps. In this study we determined the optimal density of pheromone-baited traps for monitoring S. catenifer. The experiment was conducted in 4 commercial Hass avocado orchards in Colima, Mexico, each with different pest infestation levels. Trap densities were established at 0.5, 1, 2, or 3 traps per ha. The traps were checked every 15 d and the number of moths recorded. The density of 3 traps per ha captured the most moths per trap followed by 1 trap per ha; similar small numbers of moths were captured at densities of 0.5 and 2 traps per ha. In general, there was a linear relationship between trap catch and trap density per ha. The overall default error rate, i.e., the proportion of traps did not detect moths when they were present, was 5.5% at a density of 3 traps per ha and 2.7% at trap densities of 0.5 and 2 traps per ha. Furthermore, at a density of 1 trap per ha all traps captured moths and so there was no default error. Since S. catenifer is a quarantine pest that must be detected promptly to reduce the risk of dispersal and establish-ment in moth-free areas, it is suggested that a density of 1 trap per ha should be used in avocado orchards to effectively monitor for the presence of this pest. However, this estimate was obtained through the bootstrapping technique, which involves the creation of pseudoreplicate datasets by resampling. Randomized field experiments with true replicates are needed to corroborate this result.