Attraction of Douglas-fir beetle, spruce beetle and a bark beetle predator (Coleoptera: Scolytidae and Cleridae) to enantiomers of frontalin

In three separate experiments, Douglas-fir beetles, Dendroctonus pseudotsugae Hopkins, preferred traps baited with either (S)-(-)- or racemic (R,S)-(±)-frontalin over those baited with the (R)-(+)-enantiomer. Spruce beetles, D. rufipennis (Kirby), appeared to be attracted equally to both the (S)-(-)- and (R)-(+)-enantiomers, but low catches and high variance made interpretation of the data tenuous. For both species racemic frontalin was as attractive as the preferred enantiomer alone. The bark beetle predator, Thanasimus undatulus (Say), was attracted preferentially to (S)-(-)-frontalin over (R)-(+)- or (R,S)-(±)-frontalin in a Douglas-fir stand, while both enantiomers were equally attractive in a spruce stand.Additional keywords: Dendroctonus pseudotsugae, Dendroctonus rufipennis, semiochemical, kairomones, Thanasimus undatulus, predator, trappin

Random and directed movement by Warren root collar weevils (Coleoptera: Curculionidae), relative to size and distance of host lodgepole pine trees

Hylobius warreni Wood (Coleoptera: Curculionidae) is a pest of conifers, especially lodgepole pine (Pinus contorta var. latifolia Douglas ex Loudon) (Pinales: Pinaceae) in the Interior of British Columbia. The larvae feed on the roots and root collars and cause girdling damage, resulting in mortality or growth reductions. Previous research has suggested the adult weevils locate potential host trees by using random movements and vision, but likely not chemosensory cues. The purpose of this study is to determine if adult H. warreni respond to particular tree characteristics versus encounter potential hosts at random. Study A was a capture–mark–recapture experiment where weevils were captured on mature pine trees, while Study B was a tracking experiment within a young pine plantation. Weevils showed a preference for larger trees, and for trees that were closer to the weevil’s last known location. In Study A, weevils also avoided climbing trees in poor health, while in Study B, the weevils’ preference for taller trees increased as their distance from the weevil increased, as well as when taller trees were closer to other trees. Movement rates were similar to those observed in previous studies, were positively correlated with the average spacing of trees, and declined with time after release. This confirms previous findings that H. warreni may locate host trees by both vision and random movements, and that their movements are determined primarily by the size and distribution of potential host trees within their habitat

Comparison of a-pinene and myrcene on attraction of mountain pine beetle, Dendroctonus ponderosae (Coleoptera: Scolytidae) to pheromones in stands of western white pine

Multiple-funnel traps baited with exo-brevicomin and a mixture of cis- and trans- verbenol were used to test the relative attractiveness of myrcene and (-)-a-pinene to the mountain pine beetle, Dendroctonus ponderosae Hopkins, in a stand of western white pine, Pinus monticola Dougl. Traps baited with myrcene caught significantly more D. ponderosae than traps baited with (-)-a-pinene, irrespective of the presence of exobrevicomin. exo-Brev icom in was attractive to Thanasimus undatulus (Say) (Coleoptera: Cleridae) whereas Trypodendron lineatum (Olivier) (Coleoptera: Scolytidae) was attracted to (-)-a-pinene. Our results support the use of myrcene in commercial trap lures and tree baits for D. ponderosae in stands of western white pine in British Columbia.Key words: Scolytidae; Dendroctonus ponderosae; kairomones; Pinus monticola; Trypodendron lineatum; Cleridae; Thanasimus undatulu