Complementary sampling approaches for woodland beetles, particularly saproxylic species: implications for woodland conservation monitoring

Crowe, A, O’Hanlon, A, Carlin, C, Williams, C ORCID: 0000-0003-0528-3436 and Gormally, M (2026) Complementary sampling approaches for woodland beetles, particularly saproxylic species: implications for woodland conservation monitoring. Journal of Insect Conservation, 30 (5). ISSN 1366-638X

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Abstract

Saproxylic beetles are declining across Europe due to habitat loss and limited ecological understanding. Effective, standardised sampling strategies are, therefore, required to monitor their populations and inform conservation efforts. We present the first European study to simultaneously compare flight-intercept, emergence, and pan traps for sampling woodland beetle abundance, species richness, and assemblage composition. Analyses were conducted on the entire beetle assemblages and their saproxylic subsets, thereby addressing a conservation-priority group, while also informing general beetle monitoring. We also tested pan trap colour and flight-intercept bottle direction effects on capture rates, and assessed trap-specific assemblage correlations to evaluate sampling method overlap and complementarity.
Trap type significantly affected capture rates. Flight-intercept traps collected the greatest abundance and species richness. However, all methods sampled distinct assemblage components and unique species. Pan trap colour significantly affected beetle abundance. Blue bowls outperformed white and yellow; however, all bowl colours captured unique assemblage subsets. Flight-intercept bottle direction influenced overall beetle abundance, with north-facing bottles capturing significantly fewer specimens than south and west-facing bottles. All bottle directions captured unique assemblage subsets. Flight-intercept and pan trap assemblages were significantly correlated.

We demonstrate that multi-method sampling strategies are required to capture representative woodland beetle assemblages, including for saproxylic species. Flight-intercept traps should form the core sampling method, supplemented with emergence and pan traps to broaden species coverage. Where resources are limited, pan traps may be omitted, provided flight-intercept traps are retained.

Implications for Insect Conservation
Our findings strengthen the standardisation and accuracy of woodland beetle monitoring, providing a robust evidence base for conservation planning. Understanding how trap type and design influence sampled beetle assemblages enables more representative biodiversity assessments and long-term population monitoring. These findings also inform the development of conservation tools such as habitat scorecards, national species lists, and European Red-List assessments.

Item Type:	Article
Uncontrolled Keywords:	05 Environmental Sciences; 06 Biological Sciences; Ecology; 31 Biological sciences; 41 Environmental sciences
Subjects:	Q Science > Q Science (General) Q Science > QL Zoology
Divisions:	Biological and Environmental Sciences (from Sep 19)
Publisher:	Springer
Date of acceptance:	24 July 2026
Date of first compliant Open Access:	2 October 2026
Date Deposited:	01 Oct 2026 15:29
Last Modified:	02 Oct 2026 00:50
DOI or ID number:	10.1007/s10841-026-00800-0
URI:	https://researchonline.ljmu.ac.uk/id/eprint/29593

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