Lasioglossum

Variability in the life-history strategies of the primitively eusocial sweat bee Lasioglossum malachurum (Hymenoptera: Halictidae)

Halictid sweat bees exhibit an extensive inter- and intraspecific variability with respect to their social behaviour and to the level of eusocial colony organization. There are solitary, obligately social, and facultatively social species within the family of the Halictidae.

In some obligately eusocial species like our study species Lasioglossum malachurum (Hymenoptera: Halictidae) there is also demographic variation in social behaviour with more worker broods in warmer climates. However, besides this our study population of L. malachurum in Wuerzburg shows a remarkable plasticity with respect to the pattern of worker and sexual production.

Mated females hibernate, found a nest solitarily in early spring, and raise a first brood that consist of workers only. These workers take over foraging and nest building and provision a second brood consisting of either sexuals or workers. In the case of worker production the brood cycle continues with sexual production in the third brood. However, there is also a third group of nests producing both workers and sexuals in the 2nd brood and again sexuals in the 3rd brood.

Another striking characteristic of the nesting activity of our study species is the occurrence of breaks between the different generations. There is no activity outside the nests during these breaks and nest entrances are usually closed.

The main aim of my study is to find possible endogenous and exogenous factors that might explain the variabilty in the life-history strategies of the bees.

Fotos ? Norbert Wei?el

Publications

Mitesser O, Weissel N, Strohm E, Poethke HJ (2007). Optimal investment allocation in primetively eusocial bees: a balance model based on resource limitation of the queen. Insectes Sociaux 54: 234-241

Mitesser O, Weissel N, Strohm E, Poethke HJ (2007). Adaptive dynamic resource allocation in annual eusocial insects: Environmental variation will not necessarily promote graded control. BMC Ecology 7: 16

Mitesser O, Weissel N, Strohm E, Pothke HJ (2006). The evolution of activity breaks in the nest cycle of annual eusocial bees: a model of delayed exponential growth. BMC Evolutionary Biology 6:45

Wei?el, N., Mitesser, O., Poethke, H-J., Strohm, E. (2006) The influence of soil temperature on the nesting cycle of the halictid bee Lasioglossum malachurum. Insectes Sociaux 53: 390-398

Strohm, E. and Bordon-Hauser, A. (2003). Advantages and disadvantages of large colony size in a halictid bee: the queen's perspective, Behavioral Ecology 14, 546-553.

Fotos ? Norbert Wei?el