RECIPROCAL RECOGNITION OF HOST AND NON-HOST VOLATILESBY CONIFER- AND ROSACEAN-FEEDING TORTRICIDS.

Crawford McNair, Caroline Bedard, Gerhard Gries and Regine Gries
Chemical Ecology Research Group, Simon Fraser University, Burnaby,B.C., V5A 1S6, Canada.

The spruce cone moth (SCM), Cydia strobillella and the cherrybark tortrix (CBT), Enarmonia formosana, infest spruce cones (SCM)and Rosacean trees (CBT). We have tested the hypothesis that selectionof host trees (oviposition sites) by SCM and CBT involves the recognitionof semiochemicals from both host and non-host volatiles. Volatiles fromspruce conelets, cherry and the phloem/xylem of other coniferous and deciduoustrees were captured on Porapak Q. Gas chromatographic-electroantennographicdetection analysis of volatile extracts with SCM and CBT antennae revealedgood responses to both host and non-host volatiles. A mixture of EAD-activeconelet volatiles attracted female SCM in laboratory bioassays. EAD-activevolatiles from non-host deciduous trees, in contrast, reduced the attractivenessof pheromone-baited traps in field experiments. Similarly, in binary choicetests female CBT laid significantly more eggs on untreated cherry branchesthan on those baited with EAD-active, non-host volatile a-pinene.These results support the hypothesis that host selection by SCM and CBT is mediated by volatiles from both host and non-host species. Non-hostvolatiles may be utilised to render suitable trees unattractive to gravidhost-seeking female moths.