The whitefly Bemisia tabaci is the second most widespread and economically important arthropod pest in the world, with frequent population outbreaks occurring in Brazil and increasing economic damage on soybean crops. High oviposition rate, short life cycle and uneven distribution along the plants’ canopy favour the dissemination of B. tabaci within soybean crops and compromise the efficacy of control measures. The objective of this work was to quantify soybean yield reduction caused by B. tabaci damage and propose an economic injury level (EIL) for this pest in soybean crops. Experimental design was randomized blocks with four replicates. Soybean grain yield and its components (number of pods, number of grains and 1000-grain weight) were quantified in relation to different levels of B. tabaci infestation in two cropping seasons, obtained through insecticide sprays carried out at different growth stages of the soybean plants. The resulting data were submitted to variance analysis, mean separation test and regression analysis. We found that a population density of one whitefly trifoliate⁻¹ reduces from 0.88 to 1.79 grains plant⁻¹, 0.16 ± 0.01 g plant⁻¹ or 31.24 ± 4.21 kg ha⁻¹of grain yield, and varies in response for pods plant⁻¹ and 1000-grains weight. Based on this information, we suggest an economic injury level of 1.465 ± 0.195 B. tabaci trifoliate⁻¹, considering a control cost of US$ 20.00 ha^-1 and soybean crop value of US$ 400.00 tonne⁻¹.

烟粉虱烟粉虱是世界上第二大和经济上重要的节肢动物害虫，巴西频繁发生种群暴发，对大豆作物的经济破坏日益严重。较高的排卵率，较短的生命周期和沿植物冠层的不均匀分布有利于烟粉虱在大豆作物中的传播，并损害了防治措施的效力。这项工作的目的是量化由烟粉虱引起的大豆减产。损害并提出对大豆作物中该害虫的经济损害水平（EIL）。实验设计是具有四个重复的随机区组。相对于两个种植季节中不同水平的烟粉虱侵染，通过在大豆的不同生长阶段进行的杀虫剂喷雾获得的大豆籽粒产量及其组成（荚果数，粒数和1000粒重）进行了定量植物。将所得数据提交给方差分析，均值分离检验和回归分析。我们发现，一个粉虱枳的人口密度^-1降低了从0.88至1.79的晶粒植物^-1，0.16±0.01克植物^-1或31.24±4.21公斤公顷^-1籽粒产量的变化，并且因豆荚植物^-1和1000粒重而变化。基于这些信息，我们建议1.465±0.195的经济损失水平烟粉虱枳^-1，考虑到US $ 20.00公顷，控制成本^-1和大豆作物的美国价值$ 400.00吨^-1。