Behavioural observations of mating disruption in three lepidopteran pests

The effect of long term exposure to sex pheromones on calling behaviour and mating in three important lepidopteran pests, the European grape berry moth, Eupoecillia ambiguella (Hubner), the European grapevine moth, Lobesia botrana (Denis & Schiffermuller), and the Egyptian cotton leafworm, Spodoptera littoralis (Boisduval) were investigated in laboratory experiments. In the three species, permanent exposure of females to their main sex pheromone compound did not alter either the onset or the patterns in the calling activity. When both males and females of each species were constantly exposed to their main sex pheromone compound, the percentage of females that were mated was significantly reduced. However, the degree of mating suppression varied, with 100%, 86%, and 53% in E. ambiguella, L. botrana and S. littoralis, respectively. These results indicate that males but not females are the only sex that is primarily affected by permanent exposure to sex pheromone. It also suggests that sensory overload which results in adaptation in the olfactory sensilla and/or habituation in central nervous system is the key mechanism of mating disruption in the three species.