Biological parameters of three Trichogramma pretiosum strains (Riley, 1879) (Hymenoptera: Trichogrammatidae) on eggs Helicoverpa armigera (Hübner, 1805) (Lepidoptera: Noctuidae)

Abstract

This project has an objective to study the biological parameters of Trichogramma pretiosum on eggs of H. armigera. The three strains of T. pretiosum were evaluated: TM, TMC and TLEM, from different places. The experimental establishing was completely randomizing with twenty repeats per treatment, being used by a female parasitoid by repetition and later on they were offered 20 H. armigera eggs. The experiment was kept on BOD cameras to 25 ± 2° C, UR 60 ± 10% and photo phase of 14 hours. Evaluating the following biological parameters: parasitism percentage, emergency percentage, number of adults emerged per egg, sex ratio, viability, and longevity and cycle duration. The parasitism percentage, viability and number of individuals per egg were higher for TM and TMC. The TMC strain presented a larger sex ratio proportion, not being different statistically from the TM stream. The longevity of the strain TM was different regarding the others. There was no variation regarding the cycle duration. Therefore, according with the evaluated biologic parameters, it is concluded that Trichogramma pretiosum strain TM obtained a better egg development of H. armigera on laboratory conditions.