Characterization of tolerance in the soybean KS-4202 to Bemisia tabaci biotype B

Since it was first reported in Brazil in the 1990s, the B biotype of sweetpotato whitefly, Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae), has been recognized as an important pest in soybeans (Glycine max L.), reducing the productivity of this legume species in some areas of the country. As an alternative to chemical control, the use of resistant genotypes represents an important tool for integrated pest management (IPM). In this greenhouse study we evaluated the soybean genotype KS4202 for tolerance to B. tabaci biotype B. Seeds of two soybean genotypes, a susceptible line Conquista and a soybean aphid tolerant line KS-4202, were selected for this study. Three seeds of each genotype were planted in round plastic pots (5 L) and after germination plants were thinned to one plant per pot. Plants were maintained in a greenhouse (25 ± 5°C; 50 ±10% RH; 6:8 L:D h). The experimental design was a completely randomized design, with a 2 x 6 factorial treatment design that included two soybean lines, and six whitefly infestation periods. Each treatment combination was replicated four times. Upon maturation, soybean pods were harvested and placed in a paper bag and dried to adjust seed moisture level to 13% prior processing. The yield parameters of each plant were individually calculated by evaluating the number of pods/plant, average dry weight of pod, total number of seeds/plant, average seed weight and total biomass. Whitefly infestation was negatively correlated with all yield components in Conquista line even under the shortest period of whitefly infestation (15 days). For KS-4202 there were no significant differences on yield components in both uninfested and infested (15, 30, 45 and 60 days) plants with B. tabaci biotype B. These results indicate that KS-4202 has tolerance to sweetpotato whitefly feeding.