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Selectivity of different pesticides used in soybean to the eggs parasitoid Telenomus remus

Biological control agent preservation is crucial to the integrated pest management success. However, chemical control is yet useful for crop production. Thus, pesticide selectivity to beneficial insects is a feature that must always be taken into account in order to choose the best chemical. Therefore, this research studied the impact caused by different pesticides in the egg parasitoid, Telenomus remus Nixon (Hymenoptera: Scelionidae) emergence, when sprayed on the larvae and pupae stage (Egg masses from 100 to 150 eggs of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) six and ten days after the parasitism, respectively). Three trials, with 11 treatments and 5 repetitions, were carried out in the laboratory with insecticides, fungicides and herbicides. Each test was carried out with 10 treatments of chemicals and water as control. All chemicals were tested at rates used in soybean crops. Eggs of S. frugiperda parasitized by T. remus, were immersed in the treatments for five seconds. After completely dry, they were placed in plastic bags until the emergence of adults of parasitoids. The viability of parasitism was evaluated and the reduction in the emergence of the parasitoids classified according to the rules of the International Organization for Biological Control (IOBC). The results showed that the insect growth-regulating (IGR) insecticides flufenoxuron, diflubenzuron, methoxyfenozide as well as the insecticides imidacloprid + beta-cyfluthrin and acephate were harmless to the parasitoid immature stages . Spinosad was classified as harmless for larvae of T. remus. Gama-cyhalothrin was slightly harmful to larvae and harmless to pupa of T. remus. Bifenthrin and chlorpyrifos were, respectively, slightly harmful and harmful to both stages of development of T. remus development. Regarding to the tested herbicides, 2,4-D, s-metolachlor, flumioxazin, paraquat dichloride + diuron, paraquat dichloride and glyphosate (Roundup Transorb®) were harmless. However, glyphosate + imazethapyr, clomazone, glyphosate (Gliz®), glyphosate (Roundup Ready®) were harmless to the larvae stage and slightly harmful (class 2) to T. remus pupae. Similar results were obtained with the fungicides flutriafol + tiofanate, carbenzadin, tebuconazol + trifloxystrobin and azoxystrobin + ciproconazol which were classified as harmless. Tiofanate-metil, tebuconazol and epoxyconazol + pyraclostrobin were slightly harmful to larvae and pupae. Inversely, epoxyconazol and azoxystrobin were harmless to larvae and slightly harmful to pupae. Flutriafol was classified as slightly harmful to both development stages of T. remus.

biological control; chemical control; IOBC; Glycine max; Scelionidae


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