Socio-economics of brood destruction during supersedure in the carpenter bee Xylocopa pubescens

In nests of the facultatively social carpenter bee Xylocopa pubescens, both intruders and nestmates destroyed brood during supersedure. However, nestmates and intruders differed with respect to the frequency and the pattern of brood destruction. Intruders destroyed more brood than did nestmates. In addition, intruders appeared to destroy all stages of brood at equal frequencies, whereas nestmates had a preference for opening and thereby destroying newly made cells. Several hypotheses concerning the ultimate reasons for these differences were tested. These differences are not due to either a lack of breeding space, or to an attempt to prevent an imminent loss of dominance. The number of brood cells destroyed by nestmates was not influenced by the degree of relatedness. This indicates that the difference between nestmates and intruders was not based on active kin recognition. The most likely reason why nestmates prefer to open young brood cells is that they can then reallocate the pollen contents of these cells to their own brood. A difference in knowledge about the location of newly made cells may explain the differences in the pattern and the frequency of brood destruction by nestmates and intruders. Furthermore, a superseding nestmate may slightly enhance her average indirect fitness by destroying the brood contents of newly made cells while leaving older brood cells intact.