THE EFFECTS OF COLONY CHARACTERISTICS ON LIFE-SPAN AND FORAGING BEHAVIOR OF INDIVIDUAL WASPS (POLYBIA-OCCIDENTALIS, HYMENOPTERA, VESPIDAE)

We studied the effects of intrinsic colony characteristics and an imposed contingency on the life span and behavior of foragers in the swarm-founding social wasp Polybia occidentalis. Data were collected on marked, known-age workers introduced into four observation colonies. To test the hypothesis that colony demographic features affect worker life span, we examined the relationships of colony age and size with worker life span using survivorship analysis. Colony age and size had positive relationships with life span; marked workers from two larger, older colonies had longer life spans (XBAR = 24.7 days) than those from two smaller, younger colonies (XBAR = 20.1 days). We quantified the effects of experimentally imposed nest damage on forager behavior, to determine which of three predicted behavioral responses by foragers to this contingency (increased probability of foraging for building material, increased rate of foraging, or decrease in age of onset of foraging) would be employed. Increasing the colony level of need for materials used in nest construction (wood pulp and water) by damaging the nests of two colonies did not cause an increase in either the proportion of marked workers that gathered nest materials or in foraging rates of marked individuals, when compared with introduced workers in two simultaneously observed control colonies. Instead, nest damage caused a decrease in the age at which marked workers first foraged for pulp and water. The response to an increase in the need for building materials was an acceleration of behavioral development in some workers.