ABSTRACT
Abstract The social wasps have a remarkable system of organization in which chemical communication mediate different behavioral interactions. Among the compounds involved in this process, cuticular hydrocarbons are considered the main signals for nestmate recognition, caste differentiation, and fertility communication. The aims of this study were to describe the cuticular chemical compounds of the species Mischocyttarus consimilis, Mischocyttarus bertonii, and Mischocyttarus latior, and to test whether these chemical compounds could be used to evaluate differences and similarities between Mischocyttarus species, using gas chromatography coupled to mass spectrometry (GC-MS). Workers from these three species presented a variety of hydrocarbons ranging from C17 to C37, and among the compounds identified, the most representative were branched alkanes, linear alkanes and alkenes. The results revealed quantitative and qualitative differences among the hydrocarbon profiles, as confirmed by discriminant analysis. This study supports the hypothesis that cuticular chemical profiles can be used as parameters to identify interspecific and intercolony differences in Mischocyttarus, highlighting the importance of these compounds for differentiation of species and populations.
ABSTRACT
ABSTRACT In leafcutter ants the division of labour is associated to worker size variation clustered in four subcastes. In this work we used Atta sexdens Forel (1908) as a model to test the hypothesis that each subcaste expresses its own chemical signature comprised of cuticular lipids. To assess it, we extracted epicuticular compounds by using nonpolar solvent hexane and analysed the samples in a combined Gas Chromatography-Mass Spectrometer (GC-MS). We found 24 hydrocarbons with carbon chains ranging from 19 to 39 atoms most of them classified as linear and branched alkanes. No compound occurred in the cuticle of specific worker subcaste, however, the relative proportion pattern varied greatly among them. Our results suggest that although subcastes have similar chemical signatures, significant differences in their relative proportions may play an important role between nestmate and group identification.
ABSTRACT
Nestmate recognition is one the most important features in social insect colonies. Although epicuticular lipids or cuticular hydrocarbons have both structural and defensive functions in insects, they also seem to be involved in several aspects of communication in wasps, bees and ants. We analyzed and described for the first time the cuticular hydrocarbons of a Neotropical paper wasp, Polistes satan, and found that variation in hydrocarbon profile was sufficiently strong to discriminate individuals according to their colony membership. Therefore, it seems that small differences in the proportion of these compounds can be detected and used as a chemical-based cue by nestmates to detect invaders and avoid usurpation.
Subject(s)
Animals , Female , Hydrocarbons/chemistry , Biological Assay , Behavior, Animal , Social Behavior , Animal Communication , Chromatography, Gas , Larva , Models, Biological , Odorants , Ovary/metabolism , WaspsABSTRACT
Diploid males have long been considered a curiosity contradictory to the haplo-diploid mode of sex determination in the Hymenoptera. In Apis mellifera, 'false' diploid male larvae are eliminated by worker cannibalism immediately after hatching. A 'cannibalism substance' produced by diploid drone larvae to induce worker-assisted suicide has been hypothesized, but it has never been detected. Diploid drones are only removed some hours after hatching. Older larvae are evidently not regarded as 'false males' and instead are regularly nursed by the brood-attending worker bees. As the pheromonal cues presumably are located on the surface of newly hatched bee larvae, we extracted the cuticular secretions and analyzed their chemical composition by gas chromatograph-mass spectrometry (GC-MS) analyses. Larvae were sexed and then reared in vitro for up to three days. The GC-MS pattern that was obtained, with alkanes as the major compounds, was compared between diploid and haploid drone larvae. We also examined some physical parameters of adult drones. There was no difference between diploid and haploid males in their weight at the day of emergence. The diploid adult drones had fewer wing hooks and smaller testes. The sperm DNA content was 0.30 and 0.15 pg per nucleus, giving an exact 2:1 ratio for the gametocytes of diploid and haploid drones, respectively. Vitellogenin was found in the hemolymph of both types of imaginal drones at 5 to 6 days, with a significantly lower titer in the diploids.