Defensive secretions of larvae of a carabid beetle

Abstract

Secretions of an eversible gland on the metathorax of larvae of Chlaenius cordicollis Kirby (Coleoptera: Carabidae) are investigated by headspace analysis using solid phase microextraction followed by gas chromatography‐mass spectrometry (GC‐MS). Larvae from Manitoba, Canada and Pennsylvania, U.S.A., are sampled. Nine presumed defensive compounds are detected when the gland is everted, and this represents the first characterization of defensive secretions of larvae of a carabid beetle. With the exception of a single component (2‐methoxy‐4‐methylphenol), these compounds are distinct from those found in the defensive secretion of adult C. cordicollis. However, seven are more oxidized versions of the alkylphenolic compounds secreted by adult beetles: three hydroquinones (hydroquinone, methylhydroquinone and 2,3‐dimethylhydroquinone) and four quinones (p‐benzoquinone, toluquinone, 2,3‐dimethylquinone and ethyl‐p‐benzoquinone). An additional alkoxyphenol (2‐methoxy‐4‐ethylphenol) is also detected. Two patterns of composition are observed: in one, p‐benzoquinone and hydroquinone are undetectable and the ratio of toluquinone : 2,3‐dimethylquinone is 1 : 4.6 ± 0.6 (mean ± SE); in the other, all nine compounds are detectable and the ratio of toluquinone : 2,3‐dimethylquinone is 1 : 1.0 ± 0.2. These differences in pattern do not appear to be related to geographical source, sex or age of the larvae.

Transcriptome analysis reveals candidate genes involved in luciferin metabolism inLuciola aquatilis(Coleoptera: Lampyridae)

“…Both larva and adult leaf beetles (family Chrysomelidae) are also known to produce defensive compounds such as isoaxazolinone glucoside 5 and its 3-nitropropionate esters 6 to prevent them from natural enemies ( Pauls et al, 2016 ). In the larvae of carabid beetle, Chlaenius cordicollis , various defensive compounds, e.g., methylhydroquinone, toluquinone 2,3-dimethylquinone were detected ( Holliday, Mattingly & Holliday, 2015 ). Due to these diverse yet species-specific metabolites found among groups of insect, when the database searches were performed, only a small number of genes were annotated as being involved in the metabolism of terpenoids and polyketides in L. aquatilis .…”

RNA Sequencing, De novo assembly, functional annotation and SSR analysis of the endangered diving beetle Cybister chinensis (= Cybister japonicus) using the Illumina platform

“…These pathways may be required to establish the ecological dependence, interactions, and evolutionary relationships (Pankewitz and Hilker 2008). Two sequences classified to ubiquinone and other terpenoidquinone biosynthesis pathway consistent to the detection of methylhydroquinone, and toluquinone 2, 3-dimethylquinone in the larval transcriptome of the carabid beetle, Chlaenius cordicollis (Holliday et al 2015). Among the organismal system category, the sequences were classified to the immune system pathways (194 sequences; 98 sequences of which classified to T-cell receptor signalling pathway).…”