Selectivity of chlorantraniliprole and lambda-cyhalothrin to the egg parasitoid Telenomus podisi (Hymenoptera: Platygastridae)

Abstract

Soybean plants host a diverse complex of pest insects, which can occur simultaneously during crop development. Thus, the use of egg parasitoids for the management of Euschistus heros (Fabricius) (Hemiptera: Pentatomidae) depends on the selectivity of the pesticides to the stink bug. Thus, the selectivity of the active ingredients chlorantraniliprole and chlorantraniliprole + lambda-cyhalothrin to the parasitoid Telenomus podisi (Ashmead) (Hymenoptera: Platygastridae) was evaluated. The bioassays were carried out under controlled conditions (27 ± 2 ºC and 50 ± 10% relative humidity) for the pupal and adult phases of the parasitoid. The design was completely randomized, with 10 treatments and five replicates composed of the insecticides chlorantraniliprole and chlorantraniliprole + lambda-cyhalothrin in different doses, as well as a negative control using water and a positive control using chlorpyrifos. We used a Potter Tower for the applications, and evaluations were carried out 24, 72, and 120 hours after the applications. Experimental methods and analyses to determine the harmfulness of the products to the insects were in accordance with International Organization for Biological Control standards. Chlorantraniliprole, at all doses tested, was less harmful to the parasitoid, especially in the adult phase; the doses were classified as class 1. The chlorantraniliprole + lambda-cyhalothrin mixture at its highest dose was classified as class 4, at 72 and 120 hours after application. For the pupal phase of the parasitoid, there were no significant differences, and the products were classified as class 1, except for the highest dose of chlorantraniliprole, which classified as class 2, at 24 hours after application. Thus, chlorantraniliprole can be considered a tool in the management of soybean pests. Its selectivity to T. podisi under the conditions tested presents low or no negative interference when sprayed on pupae and adults. However, the chlorantraniliprole + lambda-cyhalothrin mixture should be used with caution, respecting the time of application and the recommended doses, as it interferes negatively in the development of the parasitoid and should be replaced when possible.