t The pink bollworm, Pectinophoragossypiellais a key pest of cotton world-wide. In Israel mating disruption sex pheromone is used in all cotton fields and recent repeated outbreaks of the pest populations has suggested a change in the population sex pheromone characteristics. The research goals were to (1) determine the change in pheromone characteristic of PBW females after long experience to Mating Disruption (MD), (2) to test the male’s antennae response (EAG) to pheromone characteristics of laboratory, naive females, and of field collected, MD experienced females, (3) to analyse the biosynthetic pathway for possible enzyme variations, (4) to determine the male behavioural response to the pheromone blend involved in the resistance to MD. The experiments revealed that (1) MD experienced females produced pheromone blend with higher ZZ ratio than lab reared (MD naive females) that typically produced ZZ:EE ratio of 1:1. (2) Male’s origin did not affect its response to pheromone characteristics of lab or field females. (3) A transcriptome study demonstrated many gene-encode enzymes in the biosynthetic pathway, but some of the transcripts were produced in differing levels in the MD resistant populations. (4) Male origin (field or lab) influenced males’ choice of mate with strong preference to females sharing the same origin. However, when MD was applied, males of both populations were more attracted to females originated form failed MD treated fields. We conclude that in MD failed fields a change in the population mean of the ratio of the pheromone components had occurred. Males in these fields had changed their search “image” accordingly while keeping the wide range of response to all pheromone characteristics. The change in the pheromone blend is due to different level of pheromone related enzyme production.
Hybridizing transgenic Bt cotton with non-Bt cotton counters resistance in pink bollworm