Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/15/2006
Publication Date: 4/5/2007
Citation: Horton, D.R., Landolt, P.J. 2007. Attraction of male pear psylla, cacopsylla pyricola, to female-infested pear shoots. Entomologia Experimentalis et Applicata. 123:177-183.
Interpretive Summary: Pear psylla is a destructive pest in commercial pears throughout North America and western Europe. Studies done here show that males of the overwintering population are attracted to volatile odors from female-infested pear shoots. Males were also attracted to shoots that had previously been infested by females, but from which the females were then removed. Data reported in these studies appear to be only the second example for any species of psyllid suggesting that females might emit a volatile sex attractant.
Technical Abstract: Post-diapause winterform pear psylla, Cacopsylla pyricola (Förster), exhibit a highly clumped distribution in late winter in pear orchards. The reasons for this behavior are unknown. Choice tests and assays with an olfactometer were done to test whether male psylla of the overwintering morphotype are attracted to pear shoots infested by post-diapause females and to shoots previously occupied by females. Paired choice tests showed that males accumulated on pear shoots occupied by females or previously occupied by females if those shoots were paired with uninfested shoots or shoots previously occupied by males. Cues associated with infestation or previous infestation that attracted the males are not known. Assays with an olfactometer showed that males were attracted to volatile odors from female-infested or previously infested shoots. The source of the attractants (i.e., the infested shoot, female psylla, eggs of the female psylla, or a combination of these sources) remains to be determined. Our results appear to be only the second published account at least consistent with the hypothesis that a species of Psyllidae emits a sex attractant.