Predicting the occurrence of alate aphids in Brassicaceae

the objective of this work was to predict the occurrence of alates of brevicoryne brassicae, lipaphis erysimi, and myzus persicae (hemiptera, aphididae) in brassicaceae. the alate aphids were collected in yellow water traps from july 1997 to august 2005. aphid population peaks were predicted using a degree？day model. the meteorological factors, temperature, air relative humidity, rainfall, and sunshine hours, were used to provide precision indexes to evaluate the best predictor for the date of the first capture of alate aphids by the traps. the degree？day model indicated that the peak population of the evaluated aphid species can be predicted using one of the following biofix dates: january 1st, june 1st, and the date of the first capture of the alate aphid species by the yellow water traps. the best predictor of b. brassicae occurrence is the number of days with minimum temperature >15°c, and of l. erysimi and m. persicae, the number of days with rainfall occurrence.