Frequency of overwintered Vespula germanica (Hymenoptera: Vespidae) colonies in scrubland‐pasture habitat and their impact on prey

Abstract

Overwintered Vespula germanica colonies make a major contribution to the total wasp population in some New Zealand habitats. All vespulid colonies found at two scrubland‐pasture sites near Hamilton, New Zealand, were monitored in three successive years to record the frequency of overwintering. Ten percent of V. germanica colonies overwintered but no V. vulgaris colonies did so. Prey collected by an overwintered V. germanica colony was sampled over 13 months by intercepting returning foragers. The most common prey recorded were arthropods of the orders Diptera, Araneae, and Lepidoptera. The proportions of different prey orders in the diet varied seasonally. In winter‐spring compared with summer—autumn, Diptera decreased while Lepidoptera and other orders increased. An estimated 125.6 kg of prey was carried into the two overwintered colonies for which traffic rate was measured, 29% of which was captured during winter—spring (June—November) when foragers from annual colonies are few or absent. Overwintered colonies contributed an estimated 50% of the total forager population, and consumed 70% of the total prey captured by vespulid wasps during a year in this habitat.

Key words:

• Vespula germanica
• wasps
• diet
• overwintering
• Vespidae
• forager population
• predation pressure