Dominance Order in Polistes Wasps

Abstract

A social hierarchy similar in general form and meaning to those described for many vertebrates exists in P. gallicus (Hymenoptera-Vespidae). Two individuals of P. gallicus rarely show equivalent and tolerant behavior; generally they fight each other furiously (equivalence and intolerance), or one of the 2 takes on the behavior of a dominant, the other acts as dominated (nonequivalence). The [male][male] generally present dominated behavior. In a series of contacts between 2 individuals, if certain conditions are permanent, it is always the same individual that dominates. From all the possible contacts between the [female][female] of the same nest, a sort of social order results, a "dominance scale." During the association between the wintering [female][female] which in the spring found a nest together (polygynic association), the dominance order is rigorously linear. The [alpha] is the leader or queen of the nest, and it lays eggs always; the other [female][female] lay eggs only at the beginning of the association, then their ovaries regress, and after the eclosion of the workers (in June) they are eliminated. The workers are always subordinate to the queen and also to some auxiliary [female][female]. A linear dominance order, dependent on age, exists among the first workers. Successively, certain regressions in social position happen, so that the order no longer corresponds exactly to age. If the queen is missing or has become regressive, it is the older worker (the one in the [beta]-position) that occupies her place. In the same way, if the queen disappears later, she is followed by a worker in the [beta]-position. This worker, occupying the queen''s place, in a short time is able to lay eggs. Also other workers in the higher part of the social order may become fertile. During the polygynic as- sociation and after the eclosion of the workers, each individual shows the maximum frequency of dominance toward the one immediately below it in social position. The following factors influence dominance: the condition of the ovaries (in the contacts between 2 individuals, it is the one with more developed ovaries that dominates); age, perhaps in strict relation with ovarian development; sex; growing old or other debilitation; some psychological factors. The difference in place occupied on the nest is a fact connected (though not rigorously) with the system of dominance. Dominance causes a trophic advantage, considering that the case of a dominant 9 being fed by a dominated one is much more frequent than is the opposite condition. A relation between dominance and work distribution also exists: i.e., the individuals of lower social status undertake the greater part of the external work, while the work on the nest is done mainly by the wasps in higher position. The a specializes in laying eggs. Among the [female][female] that are somewhat more active than passive in their behavior, social domination brings a further ovarian development and fertility as a consequence of the action of the connected advantage of a trophic nature. The system of dominance influences the condition of sterility which, it seems, is to be attributed, in part at least, to a sort of castration for work in the dominated individuals of lower social status. In P. gallicus the production of sterile and fertile forms is an indirect consequence of the dominance system, and it is independent of the nutrition received during larval life.