Studies were conducted to evaluate the effect of the application of inducers on the resistance of 2 soyabean cultivars to the whitefly Bemisia tabaci Biotype B. The seeds of the soyabean cultivars IAC-19 and MONSOY-8001 were previously treated with captan. The following treatments were tested: irrigating the soil around the plants of each pot with 250 ml solution of 1.0% silicic acid (T1); spraying of the plants, to the 'point of dripping', with a solution of 0.3% acibenzolar-S-methyl (T2); spraying of the plants, to the 'point of dripping', with a solution of 0.24% pyraclostrobin+epoxiconazole (T3); and control (T4). The plants were infested with 100 adult whiteflies that were released 8 days after applying the treatments. The number of ova on the abaxial face of each leaf, which was marked for further evaluation of nymphs, tannin and lignin contents and dry weight of the aerial parts and roots. There was no difference for the number of ova and nymphs among the soyabean cultivars. Nevertheless, the average survival rate of B. tabaci was lower on cultivar IAC-19. The application of silicon or acibenzolar-s-methyl induced an increase in lignin content in the soyabean cultivar IAC-19.
