Evolution of the sex pheromone of male European beewolves (Philanthus triangulum, Hymenoptera, Crabronidae)

Male European beewolves establish small territories in the vicinity of the females' nests and defend these territories against intruding males. They mark the vegetation with a cephalic gland secretion. Territories of several different males are often found close together, thereby costituting a lek situation in which females have an ideal opportunity to choose among potential mates. Females usually approach territories from the downwind side. Copulations with males often take place within the males' territories, and they are not preceeded by any kind of visual courtship behaviour. The sex pheromone consists of a number of compounds with Z-11-eicosenol making up the major component. Surprisingly, honeybees – the prey of the beewolf females – possess the same compound in their alarm pheromone. According to the sensory exploitation hypothesis we hypothesised a three step scenario for the evolution of the composition of the sex pheromone. First, honeybees smell of eicosenol. Second, female beewolves use eicosenol either to locate or identify their prey and have therefore evolved a high sensory sensitivity for this substance. Third, males have integrated this compound in their pheromone to attract the attention of receptive females. With a combination of behavioural assays and chemical analyses, we found evidence for all these steps. We are currently investigating whether females choose mates on the basis of this pheromone. We are particularly interested in whether the composition and/or amount of the male pheromone vary with size, age, relatedness, and geographical origin. Femals could then use such information on many different aspects of mate quality to choose the best mate. Using microsatellites, we are currently testing whether females choose adaptively among potential mates.



Kaltenpoth M, Kroiss J, Strohm E (2007) The odor of origin: kinship and geographical distance are reflected in the marking pheromone of male beewolves (Philanthus triangulum F., Hymenoptera, Crabronidae). BMC Ecology 7:11.

Schmitt T, Herzner G, Weckerle B, Schreier P, Strohm E (2007). Volatiles of foraging honeybees Apis mellifera L. (Hymenoptera: Apidae) and their potential role as semiochemicals. Apidologie 38: DOI: 10.1051/apido:2006067.

Herzner G, Goettler W, Kroiss J, Purea A, Webb A, Jakob PM., Rössler W, Strohm E (2007). Males of a solitary wasp possess a postpharyngeal gland. Arthropod Structure & Development 36: 123-133.

Kroiss J, Schmitt T, Schreier P, Strohm E, Herzner G (2006). A selfish function of a social gland? A postpharyngeal gland functions as sex pheromone reservoir in males of a solitary wasp. Journal of Chemical Ecology 32: 2763-2776.

Kaltenpoth, M., Strohm, E. (2006). The scent of senescence: Age-dependent changes in the composition of the marking pheromone of the male European beewolf (Philanthus triangulum, Hymenoptera, Crabronidae). Journal of Insect Science 6:20.

Herzner, G., Schmitt, T., Heckel, F., Schreier, P. and Strohm, E. (2006). Brothers smell similar: Variation in the sex pherome of male European Beewolves and its implications for inbreeding avoidance. Biological Journal of the Linnean Society 89: 433-442.

Herzner, G., Schmitt, T., Linsenmair, K. E. and Strohm, E. (2005). Prey recognition by females of the European beewolf and its potential for a sensory trap. Animal Behaviour 70, 1411-1418.

Kaltenpoth, M., Strohm, E. and Gadau, J. (2004). Polymorphic microsatellite markers for a solitary digger wasp, the European beewolf (Philanthus triangulum; Hymenoptera, Sphecidae). Molecular Ecology Notes 4: 589-592.

Schmitt, T., Strohm, E., Herzner, G., Bicchi, C., Krammer, G., Heckel, F. and Schreier, P. (2003). (S)-2,3-dihydrofarnesoic acid, a new component in cephalic glands of male european beewolves Philanthus triangulum, J. Chem. Ecol. 29, 2469-2479.

Herzner, G., Schmitt, T., Linsenmair, K. E. and Strohm, E. (2003). Flagellar sensilla in male and female European beewolves, Philanthus triangulum F. (Hymenoptera : Sphecidae), Entomol. Fenn. 14, 237-247.

Strohm, E. and Lechner, K. (2000). Male size does not affect territorial behaviour and life history traits in a sphecid wasp, Animal Behaviour 59, 183-191.

Male beewolf marking its territory with the pheromone from the cephalic gland.
Male beewolf guarding its territory.

Fotos © Martin Kaltenpoth