Field tests were conducted with Hylobius abietis (L.) in Sweden during 1982 and 1983 to study how weevils feeding on host material affect attractivity of this host material to other H. abietis Pitfall traps baited with a combination of male or female weevils and cut stems of Scots pine caught more weevils of both sexes than pine alone. Weevils of either sex were not attractive in absence of host material. Attractivity of ground phloem containing weevil frass was not significantly different from that of ground phloem alone. In a laboratory test, feeding by weevils of either sex on pine about doubled the release of monoterpene hydrocarbons and ethanol compared with pine alone. Existence of an aggregation pheromone could not be confirmed. We suggest that weevil aggregations are formed in response to host volatiles and that weevil feeding increases amounts of these volatiles released.
3,7-Dimethylpentadecan-2-ol and 3-methylpentadecan-2-ol were identified in female whole body extracts from the two pine sawfly species Gilpinia frutetorum and Gilpinia socia. This is the first observation of 3-methylpentadecan-2-ol in extracts of a female pine sawfly species. Synthetic and highly pure stereoisomers of 3,7-dimethylpentadecan-2-ol and 3-methylpentadecan-2-ol were used to verify that the (2S,3R,7R)-isomer of 3,7-dimethylpentadecan- 2-ol and (2S,3R)-3-methylpentadecan-2-ol were present in the extracts. The four stereoisomers of 3-methylpentadecan-2-ol and their biologically active esters were produced via chemoenzymatic methods and the synthesis is described in detail. Male G. socia antennae responded strongly in EAG recordings to the (2S,3R)-isomer of the acetate and propionate of 3-methylpentadecan-2-ol. Male antennae of both G. frutetorum and G. socia also responded to the (2S,3R,7R)- and (2S,3R,7S)-acetates of 3,7-dimethylpentadecan-2-ol
