Know When You Are Too Many: Density-Dependent Release of Pheromones During Host Colonisation by the European Spruce Bark Beetle, Ips typographus (L.)
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Published:2023-10-03
Issue:11-12
Volume:49
Page:652-665
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ISSN:0098-0331
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Container-title:Journal of Chemical Ecology
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language:en
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Short-container-title:J Chem Ecol
Author:
Frühbrodt Tobias,Du Baoguo,Delb Horst,Burzlaff Tim,Kreuzwieser Jürgen,Biedermann Peter H. W.
Abstract
AbstractIndividuals across various animal species communicate their presence to conspecifics. Especially phytophagous and parasitoid insects with their brood developing on limited resources rely on chemical cues, such as host-marking pheromones, to reduce intraspecific competition. Bark beetles are phytophagous insects with some species being economically and ecologically relevant forest pests. Several of them use the volatile compound verbenone to inhibit attraction and reduce intraspecific competition. However, in the Eurasian spruce bark beetle, Ips typographus (L.), temporal emission patterns did so far not quite support the putative function of verbenone as an indicator of densely colonised host trees. More importantly, it is currently unclear how well verbenone emission is actually related to colonisation density and thus intraspecific competition. Here, we inoculated Norway spruce logs with I. typographus at two defined colonisation densities in the greenhouse and measured the emission of verbenone and its precursors α-pinene and verbenol over time. Verbenone emission was 3–7 times greater from colonised logs compared to decaying logs without beetles during the major part of larval development. Furthermore, our data supports the quantitative hypothesis, that the termination of attack on a tree is mediated by a cessation of the release of verbenol and continuous emission of verbenone. The latter is most likely a passively produced host-marking cue reflecting the actual density of conspecifics since per-beetle emission was unaffected by colonisation density. These findings shed new light on the regulation of bark beetle mass aggregations, which are currently causing previously unseen economic damages in temperate forests.
Funder
Fachagentur Nachwachsende Rohstoffe
Albert-Ludwigs-Universität Freiburg im Breisgau
Publisher
Springer Science and Business Media LLC
Subject
Biochemistry,Ecology, Evolution, Behavior and Systematics,General Medicine
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