Spatial discrimination of pheromones and behavioural antagonists by the tortricid moths Cydia pomonella and Adoxophyes orana

Male moths responding to their species-specific sea pheromone, may cease th eir upwind flight when pheromone components of sympatric species are added to the mixture. The interspecific interaction between the pheromone respons e of the tortricid moths Cydia pomonella and Adoxophyes orana was investiga ted in field-trapping and wind-tunnel studies. Addition of the A. orana phe romone [(Z9)-tetradecenylacetate and (Z11)-tetradecenylacetate] to a source containing the C. pomonella pheromone [(E8, E10)-dodecadienol] resulted in a significant inhibition of attraction by male C. pomonella. It is demonst rated that this behavioural antagonist for C. pomonella must be emitted fro m the same point source to induce this inhibitory effect. A spatial separat ion of the two interspecific pheromones (at 14 cm, 5 cm and 0.5 cm crosswin d) restored the attraction-of the conspecific pheromone for male C. pomonel la. In contrast to C. pomonella, male A. orana were not inhibited by point sources releasing both the C. pomonella and A. orana pheromone. We suggest that the discrepancy in the interspecific pheromone interaction between the se two tortricids can be explained if we consider the evolutionary ecology of interspecific pheromone communication in C. pomonella and A. orana.