Toxicity and Residual Activity of Insecticides against Diadegma insulare, a Parasitoid of the Diamondback Moth

Abstract

Plutella xylostella is the main pest of cruciferous crops worldwide. To reduce P. xylostella populations, better integration of natural control and chemical control (dominant tactic used) is needed. This work analyzed the compatibility of nine insecticides with the parasitoid Diadegma insulare, outlining them as complementary tools in an integrated pest management strategy. The acute toxicity of spinosad, imidacloprid, indoxacarb, flonicamid, naled, pyridalyl, emamectin benzoate, and spinetoram against the parasitoid was assessed. Residual activity (persistence) was also evaluated over time; the mortality of the parasitoid in contact with leaf tissue of plants treated with insecticides was analyzed. According to the International Organization of Biological Control, all nine insecticides were toxic to D. insulare; the lowest mortality was recorded with spirotetramat (64%) and pyridalyl (48%), while the rest of the insecticides caused 100% mortality at 72 h after application. In terms of persistence, by days 14, 16, 16, 17, 17, 21, and 22 after application, flonicamid, naled, spirotetramat, spinosad, piridalyl, imidacloprid, and indoxacarb caused mortality of less than 25%, respectively, so they were considered harmless (Category 1). Nonetheless, some insecticide toxicity and residual activity must be regarded within integrated pest management programs for conserving the role of D. insulare field populations.

Is Integrated Management of Gymnandrosoma aurantianum Possible with Trichogramma atopovirilia and Novel Products Used in Citrus Orchards in Brazil?

“…Knowing the persistence of products applied to surfaces can help in practical management by allowing growers to avoid releasing parasitoids until after an insecticide sprayed is no longer toxic to them [ 2 , 22 , 23 ]. Depending on the period, the parasitoid release can be associated with the application of the active ingredient of interest to improve management.…”

“…At 3, 7, 14, 21, and 30 days after the insecticides were sprayed (DAS), mature leaves from each treatment were collected and transported to the laboratory [ 23 ]. Each treatment had 20 replicates, each consisting of a 24-h-old female of T. atopovirilia and a leaf treated with the respective insecticide placed in a glass tube with a drop of pure honey and covered with plastic film.…”

Controle biológico de >i<Gymnandrosoma aurantianum>/i< Lima, 1927, o bicho-furão-dos-citros, com o parasitoide de ovos >i<Trichogramma atopovirilia>/i< Oatman & Platner, 1983

“…A persistência de produtos aplicados em superfícies pode auxiliar na prática de manejo associando um determinado princípio ativo e um parasitoide em um determinado período (Matioli et al 2019;Rakes et al 2021;Ramírez-Cerón et al 2022).…”