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Morphological Features of the Pygidial Glands and Chemical Composition of Their Secretions in Three Ground Beetle Taxa of the Tribe Chlaeniini (Coleoptera: Carabidae)
by
, , , , , , , and
Marija Vasović
1, 
Sofija Vranić
1,
Marina Todosijević
2,
Danica Pavlović
3,
Nikola Vesović
1
,
Stefan Ivanović
4,
Nina Ćurčić
5,
Milan Radovanović
5,
Ljubodrag Vujisić
2,*
and
Srećko Ćurčić
1
1
Institute of Zoology, University of Belgrade–Faculty of Biology, Studentski Trg 16, 11000 Belgrade, Serbia
2
University of Belgrade–Faculty of Chemistry, Studentski Trg 12–16, 11000 Belgrade, Serbia
3
Institute of Physics Belgrade, National Institute of the Republic of Serbia, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia
4
University of Belgrade–Institute of Chemistry, Technology and Metallurgy, National Institute of the Republic of Serbia, Njegoševa 12, 11000 Belgrade, Serbia
5
Geographical Institute “Jovan Cvijić”, Serbian Academy of Sciences and Arts, Đure Jakšića 9, 11000 Belgrade, Serbia
*
Author to whom correspondence should be addressed.
Insects 2026, 17(7), 695; https://doi.org/10.3390/insects17070695
Submission received: 27 April 2026
/
Revised: 24 June 2026
/
Accepted: 29 June 2026
/
Published: 3 July 2026
(This article belongs to the Section Insect Physiology, Reproduction and Development)
Simple Summary
Ground beetles possess a pair of defensive glands known as pygidial glands. The secretion from these glands acts as a repellent to various vertebrate and invertebrate predators. The repellent properties of the secretions result from the combined effect of different chemical compounds in the mixture. Pygidial glands and the compounds they produce are known to differ among ground beetle groups. For these reasons, we decided to morphologically examine the pygidial glands of three selected ground beetle taxa of the tribe Chlaeniini and to test chemically the defensive products of their secretions. Pygidial glands were studied using two types of microscopy, measured, and photographed. We found a relationship between the morphological features of the glands and the chemical nature of the secretions in the studied ground beetles. Among a total of 21 compounds, 3-methylphenol was the major chemical. Thirteen compounds were recorded for the first time in the tribe Chlaeniini, eight of which were new to the entire family Carabidae. Our results showed that, in some cases, along with other characters, the presence and combination of certain chemicals in the defensive secretion mixtures of ground beetles can be useful even in taxonomy.
Abstract
The relationship between the morphology of pygidial glands and the chemical nature of their secretions in the tribe Chlaeniini (family Carabidae) has long been recognised. We analysed the morphological features of the pygidial glands and the chemical composition of their secretions in three taxa: Chlaenius (Chlaeniellus) tristis (Schaller, 1783), C. (Chlaenites) spoliatus spoliatus (Rossi, 1792), and C. (Chlaenius) festivus festivus (Panzer, 1796). We examined the morphology of the pygidial glands in all three taxa using bright-field microscopy (BFM) and nonlinear microscopy (NLM). We used gas chromatography–mass spectrometry (GC–MS) and nuclear magnetic resonance (NMR) to analyse the chemical composition of the secretions. We measured and photographed the glands and conducted comparative morphological analyses. We detected a total of 21 chemicals in the pygidial gland secretions of the studied Chlaeniini. We found the highest number of compounds in C. tristis (17), slightly fewer in C. festivus festivus (13), and the lowest number in C. spoliatus spoliatus (seven). Thirteen compounds were new to the tribe Chlaeniini, eight of which were also new to the entire family Carabidae. The most dominant compound in the secretions of all three taxa was 3-methylphenol. We also discussed the taxonomic value of the chemical composition of the pygidial gland secretions.
Keywords:
Chlaenius; pygidial glands; defensive secretions; BFM; NLM; GC–MS; NMR; 3-methylphenol
