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Bioassays to evaluate the selectivity of pesticides to beneficial organisms are important tools to discriminate products compatible with biological pest control programs. This study aimed to evaluate the effects of the main insecticides used in the soybean crop on the egg parasitoid Ooencyrtus submetallicus (Hymenoptera: Encyrtidae). The tested treatments (active ingredients) were: methomyl, lambda-cyhalothrin + thiamethoxam, beta-cyfluthrin + imidacloprid, novaluron and teflubenzuron, in the highest doses indicated by the manufacturer for the soybean crop, and a control treatment (water). The evaluations enabled to calculate the mortality and parasitism capacity of adults exposed to the pesticides, in addition to the sex ratio of their descendants. Methomyl and lambda-cyhalothrin + thiamethoxam were classified as Class 4 (harmful), beta-cyfluthrin + imidacloprid as Class 3 (moderately harmful), and novaluron and teflubenzuron as Class 1 (harmless). The products classified as Class 3 and Class 4 should, as much as possible, be replaced by insecticides selective to O. submetallicus.
Knowledge about the ideal host ratio per female parasitoid reared in glass tubes is important for obtaining descendants with better biological quality. The study aimed to evaluate the reproduction of Ooencyrtus submetallicus (Hymenoptera: Encyrtidae) females in egg densities of Euschistus heros (Hemiptera: Pentatomidae) to find the most adequate relationship between parasitoids and hosts aiming at the parasitoid multiplication. The experiment was conducted with E. heros eggs at densities (parasitoid:host) of 1:3, 1:6, 1:9, 1:12, 1:15, or 1:18 with 24 hours of parasitism by O. submetallicus. The parasitoid females and the egg carton were placed in glass tubes and kept in a climate-controlled chamber. The percentage of parasitism was affected by the nonparasitised eggs. The emergence of adult parasitoids, number of parasitised eggs, number of individual parasitoids emerging per egg, the length of the parasitoids’ posterior tibiae, and the parasitoids’ longevity, life cycle, and sex ratio were not affected by the different densities of nonparasitised eggs subjected to treatments. Ooencyrtus submetallicus parasitised and developed in E. heros eggs in all evaluated densities, with 1:6 presenting the best combination of parasitoid and host.
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