Dispersal Pattern of the Sorghum Midge (Diptera: Cecidomyiidae) in Sorghum Plots

The dispersion pattern of Contarinia sorghicola Coquillet was explored by analyzing the distribution of captures along transects in grain sorghum plots. Adhesive traps at different distances from the edges of the plots were used to intercept dispersing midges. Mortality rates were determined experimentally. A passive diffusion model was fitted to the distribution of captures and the diffusion coefficient estimated. The passive diffusion model gave a good approximation to the spatial distribution of midges dispersing in sorghum plots. The estimated diffusion coefficient suggests that females disperses at a rate of 90 m2/h in sorghum plots. The model is used to predict the spatio-temporal distribution of midges dispersing inward from the edges of plots and identify areas susceptible to midge attack.