Parasitism of Heliothis virescens eggs by Trichogramma spp. can be affected by cotton cultivars

Parasitism of Heliothis virescens eggs by Trichogramma spp. can be affected by cotton cultivars. The objective of this work was to evaluate the parasitism of Heliothis virescens eggs on leaves of commercial cultivars of white (BRS 8H) and colored (BRS Safira) cotton fibers, by Trichogramma exiguum, Trichogramma pretiosum and Trichogramma atopovirilia. Thirty eggs of the pest were deposited on leaves of the respective cultivars, and exposed to each species of the parasitoid for 48 hours in controlled conditions, where they were kept until the emergence of their descendants. The parasitism rate was higher on BRS 8H cotton with better parasitism of T. atopovirilia and T. exiguum, followed by T. pretiosum. The parasitism viability was above 90%, and sexual ratio ranged from 0.79 to 1.00 on both cotton genotypes, but with lower values for T. exiguum, followed by T. atopovirilia. The number of descendants per parasitized egg of H. virescens was similar among parasitoid species, with values from 1.69 to 1.9. Overall, T. atopovirilia achieved better results on both cotton cultivars, differing from T. pretiosum. Thus, the performance of these species can be affected by cultivars. The results suggest that differences between plants are the causes of variation in the results of Trichoramma parasitism in the same culture.