CONICET | Buscador de Institutos y Recursos Humanos

The red flour beetle, Tribolium castaneum is a model organism for insect development studiesand a major stored product pest of agriculture relevance. Insect surface is covered byhydrocarbons (HC) protecting them against chemical and physical aggression. The aim of thisstudy was to identify and quantify the changes in the epicuticular HC of T. castaneum throughthe development cycle, and to investigate the potential presence of a volatile sex pheromone.Component identification was performed by capillary gas chromatography (CGC) coupled tomass spectrometry (MS); adult volatiles were extracted by solid phase microextraction (SPME)and analyzed by CGC-MS. The HC amounts increased significantly from larva to adult. Inimmature stages, saturated HC are predominant, with chain lengths of 23 to 43 carbons. Asignificantly different HC phenotype was observed in the adult stage, with large amounts ofbranched chains of 27 to 31. In this study, small amounts of a novel aldehyde component weredetected in males. Females, but not males, were attracted to this chemical in bioassays. TheMS analysis revealed a molecular weight of 210, a twelve carbon unsaturated backbone and atleast one methyl-branch. Further analyses are ongoing to fully determine the structure. Herewe show that T. castaneum HC undergo substantive changes through development, suggestinga precise regulation of the biosynthetic enzymes. The complex metabolic pathway for both,the HCs and the sex pheromone probably takes place in different tissues and is initiated by theaction of two fatty acid synthases (FASs), with different affinity to incorporate methyl branchesin the elongating chain. Five genes encoding FAS were identified in the T. castaneum genome.Studies will be started in order to identify the FAS genes responsible for HC and pheromonesynthesis. This knowledge will help understand HC biosynthesis and its regulation. Thediscovery of a sex pheromone is of interest in pest control.