HOST PLANT PREFERENCE AND ANTENNAL RESPONSES OF THEBLACK VINE WEEVIL (OTIORHYNCHUS SULCATUS) TO PLANT VOLATILES.

R.W.H.M. Van Tol and J. H. Visser¹
Research Station for Nursery Stock; P.O.Box 118, 2770 AC Boskoop, TheNetherlands ¹Research Institute for Plant Protection (IPO-DLO);P.O.Box 9060, 6700 GW Wageningen, The Netherlands

The black vine weevil (Otiorhynchus sulcatus F., Coleoptera:Curculionidae) is a serious pest in a number of ornamental plants and fruitcrops. The weevils are parthenogenetic and mainly active during the night.This nocturnal activity makes it difficult for growers to observe the presenceof weevils. Consequently pest control involves the frequent use of persistentinsecticides sprayed on the plant leaves. Although the weevil is consideredpolyphagous it shows clearly preference for plant species in the familiesRosaceae, Ericaceae and Taxaceae. Taxus species also play a crucial rôlein the development of the ovaries and the longevity of the egg-laying period.In this study we tested 82 plant volatiles on the antennae of weevils inan EAG (electroantennogram) test. Of the general green leaf volatiles (Z)-3-hexenol-1 and (E)-2-hexenol-1 show the largest responses followedby the group of (E)-2-hexenal, hexanal, hexanol-1, heptanal and (E)-2-heptenal.In general an aldehyde group or an alcohol group without a double boundreduces the response compared to the unsaturated alcohols. The ketonesand acetates in this group elicit only small responses. Responses are alsoelicited by other components like nepetalactone, nepetalactol, linalool,myrtenol and 2,5-dimethylpyrazine. Despite the polyphagous character ofthis weevil it shows a remarkable specificity in the response profile.Possible relation between volatiles distributed in plant species and theEAG results will be discussed.