Levantamento de espécies de Heliothinae associadas ao tomateiro e identificação de fontes de resistência à Helicoverpa armigera (Hübner) (Lepidoptera: noctuidae)

Abstract

Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), has caused considerable losses in tomato production either for table or for industrial processing in the Midwest of Brazil, the largest producing region. However, there is a lack of information on this pest attacking tomatoes in Brazil, a fact that makes it difficult to control. This work studied the occurrence and sources of resistance in tomato to this pest. Monitoring by light traps and larvae attacking tomato fruits in the fields were performed weekly. The material collected was subjected to DNA extraction followed by quantification to investigate the genetic diversity of Heliothinae damaging tomato fruits. Second, host preference tests and oviposition preference were conducted with different crops and 15 tomato genotypes aiming to determine the relationship of trichomes density in leaflets and flowers in the tested material and the pest preference. Light traps captured 18 lepidopteran species, with predominance of H. armigera, similar to the predominance also found in the pheromone traps. Genetic diversity analysis confirmed the predominance of H. armigera haplotype Harm1 in the samples damaging tomato fruits, plus three haplotypes of H. zea and H. virescens in the complex of Heliothinae damaging tomato fruits. Regarding the host preference, Solanum lycopersicum L. (TY 2006) exhibited the highest densities of larvae, higher percentages of defoliation and damaged fruits, different from Solanum habrochaites Knapp & Spooner (CNPH 424), which had the lowest average. The access of S. habrochaites (CNPH 424, CNPH 416, 423 and CNPH 421) had the lowest density of eggs in flowers and higher type VI glandular trichome densities. Finally, the results indicated that S. habrochaites has high potential for breeding programs aiming resistance to H. armigera.