High-dosage codling moth, Cydia pomonella L., aerosol pheromone emitters enhance rather than disrupt attraction

Field studies in Michigan apple orchards documented the effects of codlemone, (E, E)-8,10-dodecadien-1-ol, released from aerosol pheromone emitters (Suterra CM Puffer and Isomate CM MIST) on subsequent male codling moth behavior.  Pheromone plumes originating from a single aerosol emitter reduced male captures in baited traps up to 180m away. Traps within 5m of the emitter captured many males. Catch of released, marked, and sterilized moths demonstrated that males moved preferentially from areas of no or low pheromone concentration towards aerosol emitters, where they were captured in nearby traps. Additionally, moths bypassed baited traps placed between the release and recapture locations.  Dispersal of released moths in aerosol-treated orchards (1 unit ha^-1) was twice that of moths in orchards treated with high point-source density pheromone dispensers (Isomate CM FLEX, 1000 ha^-1) or those left untreated. Moths caged for 24 h on aerosol-treated foliage and then released into apple orchards had an eleveated response to traps than were males exposed to 2 Isomate FLEX dispensers or caged on untreated foliage. Overall, these findings suggest that aerosol emitters operative competitively, by causing males to displace away from females. We propose the term induced allopatry for the phenomenon of mating disruption by spatial segregation of the sexes where movement towards and aggregation near the high pheromone sources diverts males away from females that are releasing very low quantities of pheromone.