Behavioral responses of male epiphyasPostvittana (walker) to sex pheromone-baited delta trap in a wind tunnel

Abstract

The effects of parameters associated with a Delta sticky trap on the sex pheromone-mediated responses of maleEpiphyas postvittana (Walker) were tested in a wind tunnel. Males flying to a pheromone source landed closer to the source when other males were stuck on the base, suggesting the importance of visual cues in the landing behavior of males of this species. With an increase in time (numerical order of the male in the experiment), males became stuck on the base farther from the source whether or not other males were stuck on the base. The alignment of the trap to the wind or the location of the pheromone source within the trap did not significantly affect the percentages of males that entered the trap, but both significantly affected the position at which males entered the trap. When these data were corrected for the probability of catching males, a treatment with the source to the side of the trap was predicted to catch more moths than the other treatments tested, although this difference was not significant. However, in a field-trapping experiment the treatment with the source to the side caught significantly more moths than treatments with the source either in the middle or near the top of the trap. This latter result is probably due to the greater efficiency of the trap when the source is in this position, as indicated in the wind-tunnel experiment, rather than an increase in the numberof males entering the trap. Finally, the pheromone-mediated responses of malePlanotortrix octo were tested to the various trap alignments. As the angle of the trap to the wind increased, significantly fewerP. octo males entered the trap, due principally to both fewer males orienting to the source and proceeding to enter the trap after having landed on it. This difference between the responses ofP. octo andE. postvittana males is, we believe, due to the breakdown in plume structure from the source as the trap angle to the wind increases and to a greater sensitivity ofP. octo males to a more structured pheromone plume. This accounts, at least to some extent, for the consistently greater field catches ofE. postvittana overP. octo (and possibly other New Zealand leafroller moths) in many locations throughout New Zealand.