Wasp dynamics: A colony model

Social wasps are significant pests in many parts of the world, constituting a threat to human health and indigenous fauna as well as a commercial cost to industries such as beekeeping. In New Zealand Vespula vulgaris and V. germanica are significant environmental pests in large areas of native forest and, while limited chemical control is possible, for many areas there is no practical control option available. As part of a larger- scale ecological investigation into wasp biology and control, a within-colony model has been developed. The model is a simulation of intermediate complexity for which the driving relationships are drawn from an extensive field data set and published information. Although the model is conceptually similar to previous models and yields similar parameter values and output, it is mechanistically different. In particular, two new mechanistic relationships are derived: (1) the rate at which workers build cells is related to the larva:worker ratio; and (2) the rate at which the queen lays eggs is related to the number of worker-sealed brood present in the colony. Sensitivity analysis supports a possible role for queen quality in colony dynamics although other factors may also be involved. Also, sensitivity analysis results in model behaviour that is different to previous models; a result of its more mechanistic relationships. The model is intended as a tool to improve our understanding of wasp ecology and help develop effective strategies for wasp control.