Resistência de genótipos de tomateiro à Bemisia tabaci (Genn.) (Hemiptera: Aleyrodidae) biótipo B

Abstract

The whitefly Bemisia tabaci (Gen.) (Hemiptera: Aleyrodidae) is an important pest of tomato crops in Brazil. The development of tomato cultivars resistant to B. tabaci using wild tomatoes through breeding programs is an opportunity to deal with this pest. Thus, this study investigated genotypes obtained from crosses between Solanum lycopersicum L. and Solanum pimpinellifolium L. looking for resistance to B. tabaci. Non-preference for oviposition and antibiosis bioassays were conducted. Furthermore, the relationship of the density of glandular trichomes and levels of acilsugars with the resistance level found were determined. Free- and non-choice tests for oviposition were conducted in greenhouses and protected crops. The antibiosis effect on the insect development was measured determining the duration and viability of eggs and each nymphal stadium on plants growth in climatic chambers. The densities of non-glandular and glandular trichomes and the levels of acilsugars were obtained for each genotype. Based on the results from greenhouse and protected cropping, the genotypes BTR-26, BTR-42, BTR-142, BTR-228, BTR-302, and BTR-331 exhibited lower oviposition; while the genotypes BTR-63 and BTR-343 were more oviposited. Free-choice test for adults showed that the genotypes BTR- 26, BTR-42 and BTR-331 had lower densities of adults, which were considered resistant. The non-choice test for oviposition showed that the genotype BTR-331 was less preferred. Under this study the selected genotypes did not show antibiosis effects on immature stages of B. tabaci. The genotypes BTR-302 and BTR-331 exhibited greater densities of glandular trichomes, especially trichome type IV. The levels of acilsugars, however, were greater in the genotypes TO-937-15 and BTR-331. Therefore, the level of resistance against the whitefly exhibited by genotype BTR-331 was related to the densities of glandular trichomes and levels of acilsugar. These results highlight the potential of the S. pimpinellifolium as source for resistance to whitefly in the breeding programs.