Browsing by Author "Larsson, Mattias C."

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    Common Cerambycid Pheromone Components as Attractants for Longhorn Beetles (Cerambycidae) Breeding in Ephemeral Oak Substrates in Northern Europe
    (Springer, 2019-06) Molander, Mikael A.; Winde, Inis B.; Burman, Joseph; Nyabuga, Franklin N.; Lindblom, Tobias U. T.; Hanks, Lawrence M.; Millar, Jocelyn G.; Larsson, Mattias C.
    Longhorn beetles are ecologically important insects in forest ecosystems as decomposers of woody substrates, microhabitat engineers, and as components of forest food webs. These species can be greatly affected both positively and negatively by modern forestry management practices, and should be monitored accordingly. Through headspace sampling, coupled gas chromatographyelectroantennography, gas chromatography-mass spectrometry, and field bioassays, we identified two compounds, 2-methyl-1- butanol and 3-hydroxy-2-hexanone, that constitute aggregation-sex pheromone attractants of three cerambycid species which breed primarily in different types of fresh, recently dead oakwood in Northern Europe: Pyrrhidium sanguineum (L.), Phymatodes alni ssp. alni (L.), and Phymatodes testaceus (L.) (Cerambycinae: Callidiini). Analyses of headspace volatiles collected from live insects indicated that the male-produced aggregation-sex pheromone of P. sanguineum is a 1–15:100 blend of (R)-2-methyl-1-butanol and (R)-3-hydroxy-2- hexanone, whereas the corresponding ratios for P. alni were 70–110:100. In field bioassays, adult P. sanguineum and P. alni were significantly attracted to multiple blends with varying ratios of the two compounds. When tested individually, the compounds were minimally attractive. In contrast, adult P. testaceus exhibited nonspecific attraction to both of the individual compounds and to different blends, despite the hydroxyketone not being part of its pheromone, which consists of (R)-2-methyl-1-butanol alone. Overall, our results suggest that a blend of 50:100 of racemic 2-methyl-1-butanol and 3-hydroxy-2-hexanone is appropriate for parallel, cost-efficient pheromone-based monitoring of all three species. In particular, these species could serve as useful indicators of how modern forestry practices affect a whole guild of saproxylic insects that require ephemeral deadwood substrates for successful breeding.
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    Field Abundance Patterns and Odor-Mediated Host Choice by Clover Seed Weevils, Apion fulvipes and Apion trifolii (Coleoptera: Apionidae)
    (2015-02-05) Nyabuga, Franklin N.; Carrasco, David; Ranaker, Lynn; Andersson, Martin N.; Birgersson, Ran; Larsson, Mattias C.; Lundin, Ola; Rundlo, Maj; Svensson, Glenn P.; Anderbrant, Olle; Lankinen, Anda Sa
    The clover seed weevils Apion fulvipes Geoffroy, 1785 and Apion trifolii L., 1768 (Coleoptera: Apionidae) cause major losses to seed production of white clover (Trifolium repens L.) and red clover (Trifolium pratense L.), respectively. Clover is important as animal forage and an alternative to inorganic fertilizers. Because clover is mainly pollinated by bees, the use of insecticides in management of these weevils is discouraged. To gain basic knowledge for development of alternative management strategies, we investigated weevil field abundance over two growing seasons, as well as feeding and olfactory host preferences by A. fulvipes and A. trifolii. Field trap catches in southern Sweden revealed that white clover was dominated by A. fulvipes and red clover by A. trifolii. For both weevil species, female catches were positively correlated to the number of clover buds and flowers in the field. In feeding and olfactory bioassays, females of A. fulvipes and A. trifolii showed a preference for T. repens and T. pratense, respectively. However, the feeding preference was lost when the antennae were removed, indicating a significant role of olfaction in host choice. Male weevils of both species did not show clear olfactory or feeding preferences for host plant species. The field study and laboratory bioassays demonstrate that, at least for female weevils, olfaction is important for selection of host plants.We discuss these novel results in the context of managing these important pests of clover by exploiting olfaction and behavioral attraction to host plant volatiles.