SHORT COMMUNICATION Orange/lemon-scented beetles: opposite enantiomers of limonene as major constituents in the defensive secretion of related carabids Athula B. Attygalle & Xiaogang Wu & David R. Maddison & Kipling W. Will Received: 11 May 2009 / Revised: 22 July 2009 / Accepted: 23 July 2009 / Published online: 19 August 2009 # Springer-Verlag 2009 Abstract The major constituent in the pygidial gland defensive fluid of the carabid beetle Ardistomis schaumii is (R)-(+)-limonene, whereas that of Semiardistomis puncticollis is (S)-(-)-limonene. This was an unanticipated result, since it is not very common to find the opposite enantiomers of the same compound among the secondary metabolites of related species. Moreover, the glandular liquid of A. schaumii contains 1,8-cineole, and that of S. puncticollis has β-pinene, β-phellandrene, sabinene, and p-cymene. Of about 500 carabid species that have been chemically investigated, this is the first report of the presence of such complex mixtures of monoterpenes in their defensive secretions. Keywords Carabid beetle . β-pinene . p-cymene . Terpenes . Semiardistomis puncticollis . Ardistomis schaumii . Limonene Introduction One of the most species-rich families of beetles, composed of around 33,000 described species (Lorenz 2005), is the Carabidae. They are well known to produce a plethora of defensive compounds which may have contributed to their diversification (Erwin 1985). Information on the defensive chemistry of over 500 carabid species show that their defensive secretions consists mainly of hydrocarbons, acids, quinones, aliphatic ketones, and aldehydes, and a variety of other organic compounds (Will et al. 2000; Blum 1981; Weatherston and Percy 1978). Many higher plants produce essential oils consisting mainly of terpenes to protect themselves from herbivores. Terpenes are well known from some insects such as ants (Attygalle and Morgan 1984; Blum 1981), hemipteran bugs, (Aldrich et al. 1979), sawflies (Eisner et al. 1974), and termites (Quintana et al. 2003; Moore 1964). However, only a single terpene has been reported from carabid beetles (Moore and Brown 1979), although they are known to produce over 230 compounds (Attygalle and Will unpublished, Francke and Dettner 2005). Clivinini is a world-wide tribe of carabid beetles abundant in tropical and temperate zones, with approxi- mately 60 genera and nearly 1,200 described species (Lorenz 2005); however, species from only three genera of this tribe have been investigated for their defensive chemistry. Three species of Clivina Latrelle have been found to produce benzoquinones (Schildknecht et al. 1968a; Schildknecht et al. 1968b, Moore and Wallbank 1968, Kanehisa and Murase 1977), whereas Schizogenius lineolatus (Say) produces unsaturated carboxylic acids (Will et al. 2000) and Setodyschirius wilsoni (Sloane) produces exclusively aliphatic ketones and aldehydes (Moore and Brown 1979). Members of Clivinini are Electronic supplementary material The online version of this article (doi:10.1007/s00114-009-0596-8) contains supplementary material, which is available to authorized users. A. B. Attygalle (*) : X. Wu Department of Chemistry, Chemical Biology and Biomedical Engineering, Stevens Institute of Technology, Hoboken, NJ 07030, USA e-mail: athula.attygalle@stevens.edu D. R. Maddison Department of Entomology, University of Arizona, Tucson, AZ 85721, USA K. W. Will Department of Environmental Science, Policy and Management, Division of Organisms and Environment, University of California, Berkeley, CA 94720, USA Naturwissenschaften (2009) 96:1443–1449 DOI 10.1007/s00114-009-0596-8