Sex pheromone of the European tarnished plant bug, Lygus rugulipennis
1East Malling Research, New Road, East Malling, Kent ME19 6BJ, UK
2Natural Resources Institute, University of Greenwich, Chatham Maritime, Kent ME4 4TB, UK
Correspondence: jerry.cross@emr.ac.uk
The European tarnished plant bug, Lygus rugulipennis, is an important pest of horticultural crops throughout Europe. L. rugulipennis is also an important pest of cucumbers killing growing points and causing misshapen fruits. Adult male L. rugulipennis were previously shown to be attracted to traps baited with live virgin females, suggesting that the females produce a sex pheromone. Volatiles produced by virgin female L. rugulipennis were shown to contain three components, hexyl butyrate, (E)-2-hexenyl butyrate, and (E)-4-oxo-2-hexenal which elicited electroantennographic (EAG) responses from males in analyses by linked gas chromatography-electroantennography (GC-EAG). They were produced in 1.5:1:0.08 ratio, respectively, by single females and could not be detected in volatiles collected from male L. rugulipennis. In field experiments, traps baited with blends of these chemicals dispensed from polyethylene vials and sachets failed to catch significant numbers of males. However, in subsequent field experiments in which the chemicals were released from glass microcapillary tubes, a blend of hexyl butyrate and (E)-4-oxo-2-hexenal was significantly attractive to male L. rugulipennis. In addition, while the mixture of all three components attracted fewer L. rugulipennis males, this tertiary blend captured significantly greater numbers of males of the congeneric species L. pratensis than the binary mixture. The reason why the pheromone blends are attractive when dispensed from glass microcapillaries was not determined. Furthermore, release rates from microcapillary dispensers were erratic; they have only a very short field life and are impractical for operational use. The same three compounds have also been reported to be produced by both females and males of the common green capsid Lygocoris pabulinus, an important pest of a wide range of fruit crops in Europe. However, no attraction of males could be demonstrated in the laboratory or field when they were dispensed in various blends and release rates from standard pheromone dispensers. We are embarking on a new 3 year research project to understand the mechanisms and requirements for attraction of three capsid bug species L. rugulipennis, L. pabulinus and Liocoris tripustulatus (a damaging pest of sweet peppers), so that long-lived, practical dispensers can be developed and validated by growers.