Desenvolvimento de Trichospilus diatraeae (Hymenoptera: Eulophidae) em diferentes densidades e tempos de exposição em pupas de Plutella xylostella (Lepidoptera: Plutellidae)

Abstract

Plutella xylostella (Linnaeus, 1758) (Lepidoptera: Plutellidae), popularly known as diamondback moth, is responsible for causing economic damage to brassicas. Control has been taking place through the use of insecticides, often wrongly applied, triggering an increase in the frequency of resistance levels of this pest, thus creating the need to implement new management strategies, including the use of parasitoids. The objective was to evaluate the development of Trichospilus diatraeae Cherian & Margabandhu, 1942 (Hymenoptera: Eulophidae) in P. xylostella pupae subjected to different densities of parasitoid females and exposure times. To carry out the tests, females of the parasitoid with up to 24 h of life were used. P. xylostella pupae were placed in glass tubes (8.5 x 2.5 cm) and exposed to parasitism for 6, 12, 24, 48 and 72 hours, at densities 1:1, 1:3, 1: 6 and 1:9 (pupa/parasitoids) and maintained at 25 ± 2ºC, 70 ± 10% RH, photophase: 12 h. The experimental design was completely randomized, in a factorial arrangement (5 times x 4 densities) with five repetitions, each repetition being considered a set of three pupae. The highest percentage of parasitism (84%) was observed when the pupa of P. xylostella was exposed to nine females of T. diatraeae. The emergence of adults was greater when the pupa was exposed for 72 hours to a female, reaching 53%. The longevity of emerged parasitoid adults was greater when three parasitoids were used for 12 and 72 hours of exposure, recording a mean survival of 6.51 days. Finally, the sex ratio ranged from 0.87 to 1.0. It is concluded that the parasitoid T. diatraeae develops on P. xylostella pupae in laboratory with potential to control this pest.