Conflicts of interest in social insects: Male production in two species of Polistes

In social insects, reproduction is often monopolized by queens even though in many species are workers capable of laying male eggs. Because it is difficult to see how one or a few queens can suppress the much more numerous workers, collective worker control, or policing, offers an attractive solution. When workers are less related to other workers than they are to queens, workers should be selected to suppress each other in favor of the queen's male offspring, if other things are equal. Otherwise, they should allow each other to lay male eggs. For two species of Polistes, we used DNA microsatellites to estimate these two relatednesses, to determine the sex of brood, and to determine whether male brood was produced by queens or workers. Workers were significantly more related to each other (0.63 and 0.73 for P. bellicosus and P. dorsalis, respectively) than they were to queens (0.40 and 0.54, respectively) so they were predicted to allow each other to lay the male eggs. However, workers did not lay male-destined eggs in either species, so the results do not support collective worker control. There are two possible explanations for this result. Queens may be able to physically dominate in these small colonies. Alternatively, this may be a conventional settlement that minimizes conflict and the attendant costs.