Effects of height and adjacent surfaces on captures of Indianmeal moth (Lepidoptera: Pyralidae) in pheromone-baited traps.

Diamond-shaped pheromone-baited traps are used widely in food storage and food processing facilities for monitoring of Plodia interpunctella (Hübner), and here we evaluated to what extent trap captures were affected by 1) vertical placement of traps, 2) deployment of a horizontal landing platform to the diamond-shaped pheromone trap, and 3) placement of traps either freely exposed or along a sidewall. In the small sheds (height 1.8 m), traps were placed in three heights and significantly highest trap captures were obtained near the ceiling. When the same experiment was conducted in a larger room (height 6 m) with traps at seven heights, highest captures were obtained at both the lowest and highest traps. In a subsequent experiment, we deployed a horizontal platform to traps at seven heights and found that the importance of vertical placement became less important. Thus, it seemed that male moths preferred to orient to a pheromone source associated with a physical surface, such as the floor, ceiling, or landing platform. In a comparison of P. interpunctella male trap captures in a completely dark room (no visual cues), traps with a landing platform caught significantly more than traps without the platform. In a final experiment, we evaluated the effect of hanging traps either freely or adjacent to sidewalls, and significantly highest trap captures were obtained along side-walls. The results presented here suggest that deployment of a horizontal platform reduces the importance of the vertical placement of traps and seems to increase the trap efficiency, and we recommend placement of traps along sidewalls and/or near the ground.