Evidence of a female-produced sex pheromone in the European pear psylla, Cacopsylla pyri

Cacopsylla pyri (L.) (Hemiptera Psyllidae) is one of the most important pests of pear orchards in Europe that reduces the market value of pears. Summerform C. pyri males significantly preferred odours from living females or female cuticular extracts in the absence of visual stimuli in a Y-tube olfactometer. Conversely, males as well as females did not show any preference for odours from specimen of the same sex. Electroantennogram recordings showed that female cuticular extracts elicit dose-dependent responses in male antennae suggesting the presence of volatile compounds capable to stimulate the male peripheral olfactory system. Gas-chromatography coupled with mass spectrometry revealed marked quantitative differences between male and female cuticular extracts regarding 13-methylheptacosane, 11,13-dimethylheptacosane, 2-methylheptacosane, and 3-methylheptacosane. These compounds were found in larger amounts in female extracts which suggests their role in male attraction.