In search of cues: dung beetle attraction and the significance of volatile composition of dung
Volatile organic compounds (VOCs) provide animals with multiple cues about location, type, and condition of valuable resources such as food. In particular, odour cues are often essential for the localization and discrimination of resources with patchy distribution. Dung beetles (Scarabaeoidea) rely on such scented resources to locate food for their own diet and to provision their progeny. Despite the beetles’ mostly generalist choice across dung types, several studies showed that the beetles prefer some dung types over others. Yet, the importance of VOCs for dung localization and differentiation remains unclear. In this study, we used six single chemical components (indole, skatole, phenol, butyric acid, 2-butanone, and p-cresol), two different blends of these components, and six different dung types for a detailed behavioural analysis of dung beetles. We found very little specialization of beetle species towards specific VOCs. We found that dung baits and baits with synthetic compounds attracted similar communities of dung beetles, but the visitors of synthetic baits exhibited much lower diversity and abundance. The analysis of dung scent profiles of six types of dung revealed both, unique patterns in composition and ubiquitous components such as p-cresol. However, when we used a six-component blend of synthetic compounds, it turned out to be as attractive as three of the most attractive dung types in the field. Our findings highlight the significance of key VOCs, but, moreover, that dung beetles use a blend of specific components for resource localization.
KeywordsDung volatiles Scarabaeoidea Key VOC Preferences Chemical baits p-Cresol
We would like to thank Katrin Emmerich and Eckehard Rößner for their great support in species identification and Thorsten Aßmann for contributions to the Dungwebs project. We also thank Marion Ebel (Fasanerie Hanau), Jörg Beckmann (Opel-Zoo), and their staff for help in dung acquisition. We further thank Christian von Hoermann, Manfred Ayasse, and Stefan Dötterl who shared their knowledge and resources with us. We acknowledge Olena Riabinina for her helpful comments on the manuscript. We thank the managers of the three Exploratories, Kirsten Reichel-Jung, Katrin Lorenzen, and Martin Gorke, for their work in maintaining the plot and project infrastructure; Christiane Fischer and Jule Mangels for giving support through the central office, Michael Owonibi for managing the central data base, and Markus Fischer, Eduard Linsenmair, Dominik Hessenmöller, Jens Nieschulze, Daniel Prati, Ingo Schöning, François Buscot, Ernst-Detlef Schulze, Wolfgang W. Weisser, and the late Elisabeth Kalko for their role in setting up the Biodiversity Exploratories project. The work has been funded by the DFG Priority Program 1374 “Infrastructure-Biodiversity-Exploratories” (BL 960 3-1; SCHM 2645 4-1). AB was supported by the German National Academic Foundation (Studienstiftung des deutschen Volkes). Field work permits were issued by the responsible state environmental offices of Baden-Württemberg, Thüringen, and Brandenburg (according to § 72 BbgNatSchG).
KF conceived the initial idea, carried out the field and dung sampling, identified species, assisted the chemical analyses, carried out the design and formal analyses of the study, and drafted the manuscript; AB performed chemical analyses, participated in the statistical analyses, and commented on the manuscript; NB and TS acquired funding, designed and coordinated the overall study, and commented on the manuscript. All authors gave final approval for publication.
Compliance with ethical standards
Conflict of interest
All authors declare no conflict of interest.
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