The temperature has an important role both on crops and insects’ developments, whitefly Bemisia tabaci lays on temperature to regulate its lifecycle length. In this study, we evaluated the influence of temperature on the whitefly B. tabaci size population with soybean as host. Soybean was cultivated in two different years of trial, the plants were kept inside field cages (C 2.0 x W 1.7 x H 1.6 m) to avoid the interference of predators or others insects, the cages were infested in three different densities (300, 600 and 1200 adults) besides control, where no insects were released, when soybean was at the phenological stage V2, with four repetitions each treatment. The population density was accessed weekly by counting the number of eggs, nymphs, and adults on leaflets. In the first year lower temperatures (± 22°C) were observed during the period of the trial, while in the second year the average temperature was about 3°C higher (± 25°C). The density numbers in the first year peaked on the sixth week of evaluation (WOE) with an average of 23 adults per leaflet and 413 nymphs per leaflet on the eighth WOE in the higher infestation cages, while the peaks were 9 adults in the fourth WOE, and 179 nymphs per leaflet on the seventh WOE in the second year of trial. Despite the apparently subtle variance in the temperature between the years, it could cause a large difference in the number of whiteflies present in the plants.
