Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 10, 2008
Publication Date: May 9, 2008
Citation: Zhang, Q.-H., Aldrich, J.R. 2008. Sex pheromone of the plant bug, Phytocoris calli Knight. Journal of Chemical Ecology. 34:719-724.
Interpretive Summary: Worldwide there are an estimated 10,000 different kinds of plant bugs, many of which are important agricultural pests. The capability to detect when and where plant bug infestations occurs is key to their efficient management, and chemical attractants (pheromones) are a potentially powerful tool for monitoring plant bugs. Here we report the identification of the sex pheromone for another plant bug, the fifth member of a closely related group, making this group of plant bugs the most intensively studied of all in the family. From the analysis of this group of plant bugs it is obvious that these insects recognize each other by producing specific chemical blends, and they avoid each other due to the presence of inhibitors in each others pheromones. This information will be of general interest to scientists studying insect chemical communication, and will be particularly informative for those investigating the pheromone systems of other plant bugs.
Female Phytocoris sp. produce a sex pheromone from metathoracic scent glands. The pheromone consists of hexyl acetate (HA; present in both sexes), with the female-specific compounds, (E)-2-hexenyl acetate (E2HA), octyl acetate (OA) and (E)-2-octenyl acetate (E2OA). HA and E2OA are key components of the pheromone, since deletion of either ester from the blend resulted in a total shutoff of conspecific male attraction. However, the binary blend of HA and E2OA was only slightly attractive to males, and was significantly less active than the 4-component blend. The two ternary blends, HA/OA/E2OA and HA/E2HA/E2OA, were each as attractive as the full 4-component blend, but removal of both E2HA and OA from the full blend dramatically reduces the attraction of Phytocoris sp. males. Evidence from previous pheromone research on other Phytocoris species suggests that the apparent chemical redundancy in the pheromone of Phytocoris sp. may actually be involved in maintaining reproductive isolation from other sympatric species. The patterns observed for pheromones of the five Phytocoris species whose pheromones have been directly (P. californicus, P. relativus, P. difficilis, and P. sp.) or indirectly (P. breviusculus) studied are discussed vis-à-vis the as yet unidentified pheromones of intractable species such Lygus and Lygocoris plant bugs.