The odor of origin: kinship and geographical distance are reflected in the marking pheromone of male beewolves (Philanthus triangulum F., Hymenoptera, Crabronidae)

Cuticular hydrocarbons of the South American fruit fly Anastrepha fraterculus: variability with sex and age

Insect cuticular hydrocarbons are usually species-specific mixtures and may serve for species and gender recognition. They are, therefore, widely used in the chemotaxonomy and zoogeography of various insect taxa. In order to provide a basic study for further comparative analyses of cuticular hydrocarbon (CHC) profiles of cryptic species hidden within the South American fruit fly Anastrepha fraterculus complex (Diptera: Tephritidae), we analyzed the composition of the CHCs and their production with respect to age and sex in a laboratory population from Tucuman, Argentina. Several techniques of gas chromatography with mass spectrometric detection have been used in order to develop a suitable method for CHC identification, i.e., GC-MS in EI mode, GC-MS in CI mode, and GC×GC/TOFMS. Our analyses revealed a complex profile of aliphatic hydrocarbons in both males and females, consisting predominantly of n-alkanes, methyl-branched alkanes, as well as of alkenes and alkadienes. In young individuals (up to about 5 days after emergence), the CHC profiles were similar in males and females. However, in older flies, these profiles diverged and became clearly sex-specific. The temporal dynamics of the CHC patterns in both sexes were evaluated using multivariate exploratory techniques.

Larval rearing temperature influences amount and composition of the marking pheromone of the male beewolf, Philanthus triangulum

Pheromones play an important role for courtship and mating in many insect species, and they are shaped by a complex interaction of genetic and environmental factors. Developmental temperature is known to have a strong influence on adult life history, morphology, and physiology, but little is known about its effect on pheromone characteristics. In the present study, the influence of temperature during larval development on the amount and composition of the complex marking pheromone from the cephalic glands of the adult male beewolf, Philanthus triangulum F. (Hymenoptera: Crabronidae), was investigated. Additionally, the effects of temperature on several life-history traits were examined. European beewolf larvae were reared at three constant temperatures (20, 25, and 30 degrees C). Males reared at 20 degrees C showed longer development times and higher mortality, suggesting that low temperatures constitute stressful conditions for developing larvae. After eclosion, the amount and composition of the scent marking secretion of the adult males was analyzed by coupled gas chromatography-mass spectrometry. Males that had been reared at 20 degrees C had significantly less secretion than individuals reared under warmer conditions (25 degrees C and 30 degrees C). Furthermore, larval rearing temperature had a significant effect on the composition of the adult males' pheromone gland content, with warmer rearing conditions leading to higher relative amounts of compounds with high molecular weight. The results show that the temperature during larval development significantly affected the amount and composition of the content of the male pheromone glands, probably due to physiological constraints and competing processes for limited energetic resources. Thus, the pheromone gland content may contain information on developmental conditions of males, which may have consequences for female mate choice decisions and male reproductive success.