Dynamics of common wasps in New Zealand beech forests: a model with density dependence and weather

1. Nest densities of the common wasp (Vespula vulgaris (L.)) were monitored at six sites for 13 years in the honeydew-rich southern beech (Nothofagus spp.) forests of New Zealand's South Island. 2. Densities of wasp nests were among the highest in the world, up to 30 ha (-1), and at any one site varied approximately twofold over the study period. 3. Strong but not overcompensating density dependence was identified, together with a negative effect of spring rainfall. 4. The density dependence appeared to act from the number of autumn queens produced during one year to the number of mature (autumn) nests the next year, rather than through variations in queen production per nest. The same stage was also responsible for most of the variability in autumn nest numbers from year to year, with queen production per nest contributing less. 5. Yearly changes in nest density could be summarized by a simple Ricker model including both density dependence and weather, thereby incorporating both previous hypotheses for the determination of wasp abundance.