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Doctoral thesis, 2019

A pheromone-based toolbox of longhorn beetles (Cerambycidae) for monitoring biodiversity in ephemeral deadwood substrates of oak

Molander, Mikael

Abstract

Forest biodiversity is exhibiting a worldwide decline in response to environmental
changes that result in the rapid loss, degradation, and fragmentation of essential forest
habitats. Saproxylic insects, especially beetles, are an important part of forest
biodiversity by contributing to deadwood decomposition, and serving as important
components of food webs. Many saproxylic beetles display negative population trends,
and are listed on national and European Red Lists of threatened species. Despite their
great importance, present knowledge on the ecology and conservation requirements of
these beetles is limited, in part due to the absence of efficient tools to sample
populations of many species. Recently, pheromone-based methods have been proposed
as a novel tool to study saproxylic insects. Unfortunately, thus far, pheromones have
only been identified for a small number of species of interest to conservation.
In this work I identified the aggregation-sex pheromones of longhorn beetles
dependent on fresh, recently dead, wood substrates of oak in Sweden, and examined the
usefulness of the pheromone-based trapping approach for detecting local populations,
and studying the species’ ecology. The pheromone-chemistry of eight species was
considered, with a total of seven identified pheromone compounds (hydroxyketones,
alcohols, and one ketone). The pheromones were used for systematic, large-scale
monitoring studies in southern Sweden. The results served to significantly change the
perception of several species’ distribution and abundance. Further, local beetle
abundance (trap captures), was best correlated with habitat at relatively large spatial
scales, indicating that future detailed analyses of the species’ ecology need to consider
large spatial scales. Effects of oak forest management and habitat structure were
examined in a three-year monitoring study. Generally, beetle abundance did not differ
between ordinary oak production stands and two types of set-aside habitats for
biodiversity. Most species also preferred more open, sun-exposed oak habitats. In
addition, the beetles displayed short-term positive responses to logging in oak
production stands, when fresh oak substrates were retained on site. The work clearly
demonstrated the advantages of using pheromones to study these species and also
offered early insights into the complicated, and highly dynamic, ecology of the species.

Keywords

Saproxylic species, Red List, indicators, GC-MS, hydrocarbon, forest management, forest biofuel, spatial scale, nature management, conservation

Published in

Acta Universitatis Agriculturae Sueciae
2019, number: 2019:26
ISBN: 978-91-7760-370-2, eISBN: 978-91-7760-371-9
Publisher: Swedish University of Agricultural Sciences

Authors' information

Swedish University of Agricultural Sciences, Department of Plant Protection Biology

UKÄ Subject classification

Biochemistry and Molecular Biology
Ecology

URI (permanent link to this page)

https://res.slu.se/id/publ/100014