Weather-based forewarning model for the incidence of mite,Tetranychus urticae Koch (Acari: Tetranychidae) in tomato

Population dynamics of the two-spotted spider mite, Tetranychus urticae Koch was studied to develop forewarning models. Incidence of T. urticae peaked twice, the first was at 42nd standard meteorological week, MSW (18 mites/leaflet) which is below the economic threshold and the second peak at 20th MSW (60 mites/leaflet). The population of mites was positively correlated with maximum temperature (r = 0.81), minimum temperature (r = 0.71), sunshine (r = 0.60), and wind speed (r = 0.58) and negatively correlated with RH I (r = -0.87) and RH II (r = -0.79). Step-wise regression equations revealed that maximum temperature, RH I, and wind speed had a great influence on the population build-up of mites. The developed model was validated satisfactorily with RMSE= 5.97 and R2=0.84, this shows that weather factors had an 84% influence on mites infestation and its population dynamics.