Efeitos letal e subletal de agrotóxicos registrados para a cultura da soja ao parasitoide Telenomus podisi Ashmead, 1893 (Hymenoptera: Platygastridae)

Abstract

The great importance of soybean for Brazilian agribusiness justifies the investment made to increase national production. Such an increase in productivity inevitably involves the control of insect pests and diseases in the crop, which is done, to a large extent, by the application of insecticides and fungicides. The application of these pesticides can cause lethal (short term) and sublethal (long term) effects to the egg parasitoid Telenomus podisi Ashmead, 1893 (Hymenoptera: Platygastridae), one of the most efficient enemies in the biological control of the brown bug Euschistus heros (Fabricius, 1798) (Hemiptera: Pentatomidae). Thus, the objective was to evaluate the lethal and sublethal effects of 10 pesticides registered for the cultivation of soybean to this parasitoid in the laboratory in all stages of insect development. The standard of the International Organization for Biological and Integrated Control (IOBC) was followed for the classification of pesticides in terms of their selectivity to T. podisi. In the immature stages, insecticides based on indoxacarb and lambda-cyhalothrin + thiamethoxam caused mortality of 100% of adults that emerged up to 72 hours. The insecticides based on flubendiamide, beta-cyfluthrin + imidacloprid, chlorantraniliprole and methoxyfenozid + spinetoram varied in their sublethal effects, with flubendiamide and chlorantraniliprole being the safest insecticides to be used, despite the fact that flubendiamide affected the emergence of F1 in all phases. development of the parasitoid. Beta-cyfluthrin + imidacloprid caused sublethal effects on the parasitism and F1 emergence capacity, however, it is an alternative for the control of pest bugs in soybean culture, considering that the effects were slightly harmful. Methoxyfenozid + spinetoram should be used with caution, in view of the high mortality caused in the egg and pupal phases of the parasitoid. Based on the effects on the immature stages of T. podisi, the safest fungicide for application is picoxystrobin + cyproconazole followed by trifloxystrobin + protioconazole and azoxystrobin + cyproconazole. The azoxystrobin + benzovindiflupirbased fungicide should be avoided in view of its drastic effect on the sex ratio of T. podisi at all immature stages tested. All of the tested pesticides affected the F1 sex ratio, which demands attention in the use of these products, especially with regard to monitoring crops, aiming at application only when the control levels are reached. In the adult stage of T. podisi, the diamidic insecticide based on flubendiamide affected the F1 sex ratio, while chlorantraniliprole did not cause a lethal or sublethal effect to the parasitoid. Among the tested fungicides, trifloxystrobin + protioconazole caused a sublethal effect affecting the ability of parasitism and the emergence of F1 and azoxystrobin + benzovindiflupir affected the sex ratio of the parasitoid. None of the pesticides tested had a significant lethal effect on the treated T. podisi females. The diamidic insecticides flubendiamide and chlorantraniliprole are compatible with the biological control of T. podisi and can be recommended in the soybean MIP. The fungicide trifloxystrobin + protioconazole should be used with caution, considering that it caused sublethal effects to the parasitoid.