Population Dynamics of the Social Wasps Vespula vulgaris and Vespula germanica in England

Abstract

Colonies of V. vulgaris and V. germanica (Hymenoptera: Vespidae) show the following characteristics: large variations in yearly abundance with, in the main, a 2- and possibly a 7-yr cycle, exceptional years of abundance and scarcity tend to occur in pairs, spring queens are scarce during exceptional years of summer abundance and numberous in exceptional years of summer scarcity. Further analysis of the data suggests the above characteristics are generated by an over-compensating endogenous mechanism which damps colony counts to equilibrium. The equilibrium may be perturbed by an exogenous factor. The endogenous mechanism is probably driven by either density-related intraspecific usurpation of early nests by spring queens or density-related variation in queen quality, or both. Teh exogenous factor is probably a function of summer and autumn weather. The endogenous and exogenous mechanisms are evaluated by 3 mathematical models.