First record of the spatio-temporal variation of Plutella xylostella (Lepidoptera: Plutellidae) and its parasitoids complex in the horticultural area of Córdoba city in central Argentina

Abstract

The diamondback moth, Plutella xylostella (L.) (Plutellidae: Yponomeutoidea) is the most destructive pest in Brassicaceae crops worldwide. This paper describes the status of P. xylostella and its natural enemies in a wide area around Córdoba city in the central region of Argentina. Samples were collected from fifteen horticultural plots near Córdoba City. In each plot, larvae and pupae were obtained from 10 cabbage plants during the spring of 2016 and 2017. Immature specimens were kept until an adult DBM or a parasitoid emerged. Maximum density of immature individuals per plant occurred at different moments in each sampling site, indicating local effects and dynamics of the pest. Higher densities of immature P. xylostella were observed in sites in the north-east horticultural zone of Córdoba city, where most of the farms are located. The percentage of total parasitism also varied between sites and between years but, in general, higher percentages of parasitism were observed at the end of the sampling season. Five parasitoid species were identified: Siphona sp. (Diptera: Tachinidae), Diadegma leontiniae (Hymenoptera: Ichneumonidae), Apanteles piceotrichosus (Hymenoptera: Braconidae), Oomyzus sokolowskii (Hymenoptera: Eulophidae) and the hyperparasitoid Conura pseudofulvovariegata (Hymenoptera: Chalcididae). Parasitoids behaved in a similar way to P. xylostella. Densities and dynamics were particular to each sampling site. Implications for management are discussed.