Population dynamics of Indian meal moth in coffee bean warehouses in New Jersey

Abstract

The Indian meal moth, Plodia interpunctella (Hübner), activities were monitored both inside and outside of two coffee bean warehouses in New Jersey from September 2018 to October 2020, using pheromone traps, sticky traps, light traps, and water traps. The first P. interpunctella adult appeared on pheromone traps when the average weekly temperature reached 20.7–23.8 °C inside the two warehouses. Two to three P. interpunctella peaks were found inside the warehouses. The first peak occurred from late June to early July when the average weekly temperature was 25.9 °C. The second peak occurred from late August to early September when the average weekly temperature was 26.5 °C. The third peak occurred during late September to early October when the average weekly temperature dropped to 18.6 °C. Light traps captured significantly fewer P. interpunctella than pheromone traps during first peak, but significantly more P. interpunctella during the second and third peaks. Large numbers of P. interpunctella 5th instar larvae started to appear on double-sided tape which was placed on the interior walls from week 39 of 2020. Plodia interpunctella adults distributed unevenly in the two warehouses and changed with time. Mating disruption (MD) had a significant impact on the percentage of females captured and female oviposition. However, using MD and periodic freezing of infested coffee bean bags did not cause a decline of P. interpunctella at the end of the 2.5-year study period, likely due to the frequent importation of new infested commodities. No significant difference of the P. interpunctella counts between pheromone traps installed inside and outside of the warehouses in 2019, but significant more P. interpunctella was found from inside of both warehouses in 2020. Percent of total females captured was 1.1, 39.9, 52.8 and 20.1% from pheromone traps, sticky traps, water traps, and light traps, respectively.