A simulation model for forecasting the timing of attacks of Delia radicum on cruciferous crops

Abstract

The cabbage root fly (Delia radicum) is a major pest of cruciferous crops in temperate regions of the world. A model using weather data has been developed to forecast the timing of D. radicum attacks. The model simulates development of a field population of D. radicum, commencing with the overwintering stage (diapause pupa) and following development through the first, second and, where appropriate, third generation until autumn. The model is based on a series of rate equations which describe the relationship between the rate of development of D. radicum and temperature. The model uses soil temperatures in the simulation of the development of the egg, larval and pupal stages, and air temperatures with the adult-fly stage, taking account of periods of summer dormancy (aestivation) and the onset of winter dormancy (diapause). Using local weather data or standard measurements of air and soil temperatures taken at agrometeorological stations, the model can forecast D. radicum activity in any region.