The defensive secretion of Carabus lefebvrei Dejean 1826 pupa (Coleoptera, Carabidae): gland ultrastructure and chemical identification

This study documents the defensive function of flavored humor secreted by the abdominalglands of Carabus lefebvrei pupae. The morphology and the ultrastructure of these glandswere described and the volatile compounds of glands secretion were identified by gas chromatography/mass spectrometry. The ultrastructure analysis shows an acinose complex formed by about50 clusters. Each cluster has 20 glandular units and the unit—composed of one secretory and onecanal cell lying along a duct—belongs to the class 3 cell type of Quennedey (1998). In the cytoplasm,the secretory cell contains abundant rough endoplasmatic reticula, glycogen granules,numerous mitochondria, and many well-developed Golgi complexes producing electron-dense secretorygranules. Mitochondria are large, elongated, and often adjoining electronlucent vesicles.The kind and the origin of secretory granules varying in size and density were discussed. Thechemical analysis of the gland secretion revealed the presence of a mixture of low molecular weightterpenes, ketones, aldehydes, alcohols, esters, and carboxylic acids. Monoterpenes, especially linalool,were the major products. We supposed that ketones, aldehydes, alcohols, esters, and carboxylicacids have a deterrent function against the predators and monoterpenes provide a prophylaxisfunction against pathogens