Diapause status of females affects attraction of male pear psylla, Cacopsylla pyricola, to volatiles from female‐infested pear shoots

A companion study showed that male pear psylla, Cacopsylla pyricola (Förster) (Homoptera: Psyllidae) were attracted to volatiles from pear shoots infested with post‐diapause females. The present study compared the behavioral response of males to diapause and post‐diapause females. Assays were done using a Y‐tube olfactometer. We collected male and female winterform psylla from pear orchards at regular intervals between late October (early diapause) and late February (post‐diapause). Female‐infested shoots were not attractive to males until the February samples, coinciding with ovarian maturation and onset of mating in the field. A second set of assays was done in which we manipulated diapause status in the laboratory either by exposing psylla to a long‐day photoperiod or by treating insects with an insect growth regulator, fenoxycarb. In the photoperiod experiments, both short‐day and long‐day males preferentially selected long‐day (post‐diapause) females over short‐day (diapause) females. Fenoxycarb‐treated males preferred fenoxycarb‐treated (post‐diapause) females over untreated (diapause) females; untreated males showed no preferences. Results support observations made elsewhere that male winterform pear psylla perceive and are attracted to volatile odors associated with pear shoots infested with post‐diapause females.