Interação tritrófica de cultivares de repolho, traça-das-crucíferas e do parasitóide Oomyzus sokolowskii (Kurdjumov) (Hymenoptera : Eulophidae)

Abstract

The diamondback moth (DBM), Plutella xylostella (L.) (Lepidoptera: Plutellidae), is the most important pest of brassicas throughout the world. Prospective results toward DBM manage in cabbage have been achieved using host plant resistance and biological control. However, host plant characteristics conferring resistance against herbivores might also affect their natural enemies. Thus, this work evaluated the influence of red and green (Chato-de-quintal) cabbages on the biology and oviposition preference of P. xylostella and the interaction with the larval-pupal parasitoid Oomyzus sokolowskii (Kurdjumov) (Hymenoptera: Eulophidae). Based on life history parameters for DBM, green cabbage was less favorable compared to red cabbage by delaying larval and pupal stages, and reducing female fecundity. However, under free choice tests for oviposition, DBM females preferred to lay eggs on green than red cabbage. Tests in olfactometer, isolating the color effect of the host plant, however, resulted in similar moth attraction between green and red cabbage. Foraging of O. sokolowskii females was similar on both cabbage cultivars infested with DBM larvae under large cage free choice tests. Furthermore, similar number of parasitized larvae, total number of emerged parasitoids, and adult female parasitoid longevity were found for DBM larvae reared on both cabbage cultivars under laboratory conditions. However, the period from parasitism to adult parasitoid emergence was one day shorter and a higher number of parasitoids produced per parasitized larva was achieved when parasitizing larvae reared on green cabbage. In conclusion, the results indicate a positive association of host plant resistance with the parasitism of O. sokolowskii to manage DBM and suggest that the cabbage color plays an important role on host preference for oviposition by the pest.