Nutrient Dynamics of a Swarm-founding Social Wasp Species,Polybia occidentalis (Hymenoptera: Vespidae)

The kinds, rates of acquisition, inter-individual transfers, and intra-colonial movements of nutrients were ascertained for the advanced eusocial paper wasp Polybia occidentalis (Olivier). Foraging worker wasps (“foragers”) bring arthropod prey and nutritive liquids (“nectar”) to the nest, and these are usually transferred to nest workers (“receivers”) on the outer nest envelope. Arthropod prey items, which are brought intact to the nest, are malaxated by one or more receivers before being fed to larvae; malaxating adults retain a portion of the hemolymph for their own nourishment. Nectar is usually transferred (via adult-adult torphallaxis) from foragers to receivers on the nest envelope; some nectar is given to larvae, and all adults that imbibe it retain at least some for their own nourishment. Larval saliva of P. occidentalis contains glucose, protein, and free amino acids and so is highly nutritive; the nutrient content of the saliva closely resembles that of the saliva of other social wasp taxa. Adult wasps imbibe larval saliva, but very little is apparently transferred by those adults (via trophallaxis) to nestmates. Brood cannibalism was infrequent during this study. Adult worker and male wasps possess chymotrypsin-like and trypsin-like enzyme in their midguts and so are likely capable of protein digestion. The midgut proteases show an age-correlated variation in concentration. Pulp foragers are significantly smaller and lighter in weight than are receivers.