Bemisia tabaci MEAM1 (Hemiptera: Aleyrodidae) is a key insect pest in soybean fields in Brazil. Temperature influences its development affecting the lifecycle length, population size, and crop yield. This study investigated different densities of B. tabaci that can affect soybean yield and change in vigor and protein content of soybean grains. Differences in temperature in the two harvest years affected the population density of B. tabaci, reaching 413 nymphs per leaflet in the first year, and 179 the second year, when the average temperature was 3 ºC higher. The higher temperature promoted a shorter lifecycle and, as consequence, more B. tabaci generations with less overlap in the leaves. Yield was affected with losses up to 500 kg ha -1 in 2017/2018 and 1,147 kg ha -1 in 2018/2019. We also observed a decrease in the weight of thousand grains of 18 g in the first year and 33 g in the second. Although no significant differences were observed among the grains' vigor quality, estimated losses were up to 440 kg ha -1 in protein content. Bemisia tabaci MEAM1 can cause yield losses over a ton in a soybean field and, in temperatures around 25 ºC it represented 30% of total production. Although the vigor parameters of soybean grains were not affected, the infestations resulted in losses in the grains' protein content. Establishing IPM programs is a challenge, and there is a constant need for improvement. Results, as shown in this study, can be helpful in the decision making to control the whitefly in soybean areas.