RESUMEN
ABSTRACT This study investigated the interaction between two pest biological control agents, the parasitoid wasp Trichogramma pretiosum (Hymenoptera: Trichogrammatidae) and the entomopathogen Bacillus thuringiensis (Bacillales: Bacillacea) (Bt). The aim of this study was to evaluate if the presence of Bt (formulated products Agree®, Dipel® and HD1 and HD11 strains) interferes in the oviposition preference of T. pretiosum to eggs of Helicoverpa zea (Lepidoptera: Noctuidae). Using an olfactometry test, the eggs of H. zea were bathed with the commercial formulations, with the Bt suspensions or distilled water, and offered to the parasitoid wasps in order to evaluate parasitism. The results showed that H. zea eggs sprayed with commercial formulations and Bt strains did not interfere in the choice made by the parasitoid. The parasitoid wasp is not able to distinguish between eggs with or without B. thuringiensis treatment, independently of strains suspension or commercial formulations. Therefore, these two control agents may be used together without negative interaction.
RESUMEN
The study reports a field survey to determine the presence of parasitism on the leaf defoliator Hypocala andremona (Stoll) (Lepidoptera: Noctuidae) eggs, on parsimmon trees by Trichogrammatids. H. andremona eggs were sampled weekly on two branches/10 trees/orchard during the 2000/01 and 2001/02 crop seasons in Londrina, and during 2000/01crop season in Arapongas, PR, Brazil. In laboratory the eggs were isolated in gelatin capsules and maintained under controlled conditions (26 ± 1ºC, 60 ± 10 percent RH, 14L:10D). Three parasitoid species were identified: Trichogrammatoidea annulata De Santis, Trichogramma pretiosum Riley and Trichogramma bruni Nagaraja. In Arapongas only T. pretiosum was collected. Natural control levels in general were low, but parasitization levels up to 50 percent were found during the samplings. The potential use of these biological agents to control the lepidopteran pest is discussed.
O estudo relata levantamento para determinar a ocorrência de parasitismo em ovos da lagarta do caquizeiro, Hypocala andremona (Stoll) por tricogramatídeos. Amostragens de ovos de H. andremona foram realizados semanalmente em dois ramos/10 plantas durante as safras de 2000/01 e 2001/02 em pomar de Londrina, e 2000/01 em Arapongas, PR. Em laboratório os ovos eram isolados em cápsulas de gelatina e mantidos em condições controladas (26 ± 1ºC, UR 60 ± 10 por cento e fotofase de 14h) para observação da ocorrência de parasitismo. Três espécies de parasitóides foram encontradas: Trichogrammatoidea annulata De Santis, Trichogramma pretiosum Riley e Trichogramma bruni Nagaraja em Londrina, sendo as duas primeiras espécies as mais abundantes. Em pomares de Arapongas foi coletado apenas T. pretiosum. Os níveis de parasitismo em geral foram baixos, porém parasitismo de até 50 por cento foi observado nas amostras. O potencial desses agentes biológicos para o controle da praga é discutido.