Abstract
ABSTRACT: The selectivity of eight herbicides registered for use in the wheat crop was assessed on the predators Chrysoperla externa and Eriopis connexa. Bioassays were conducted in the laboratory by exposing larvae, eggs, and pupae of these predators to dry residues of the herbicides 2,4-D amine, bentazon, glyphosate 1.200, glyphosate 1.440, ammonium glufosinate, iodosulfuron-methyl, metsulfuron-methyl, and pyrimidinedione. The herbicide ammonium glufosinate was classified as moderately harmful (class 3) to the larval stage of both predators. In the egg stage, only metsulfuron-methyl showed a reduction in larval hatching higher than 30% and was classified as slightly harmful (class 2) to eggs of E. connexa. The herbicide 2,4-D amine was classified as slightly harmful (class 2) to pupae of C. externa, while pyrimidinedione presented the same classification to pupae of E. connexa. The herbicides bentazon, glyphosate 1.200, glyphosate 1.440, and iodosulfuron-methyl were considered as innocuous to the stages of larva, egg, and pupa of C. externa and E. connexa and can be used in the integrated pest management of wheat crop, assisting in predator conservation.
Highlights
Several factors act as limiting to obtain a high productivity in wheat crop, especially weeds, which cause a decrease in yield due to the competition for resources available in the medium (Agostinetto et al, 2008)
The use of selective pesticides is of paramount importance to delay or even avoid problems arising from their indiscriminate use
The herbicide ammonium glufosinate presented a larval mortality of 80% (Table 1) when larvae of C. externa were exposed to the residual contact with herbicides, not being possible to safely assess their sublethal effects on the reproductive parameters of adults from larvae exposed to herbicides
Summary
Several factors act as limiting to obtain a high productivity in wheat crop, especially weeds, which cause a decrease in yield due to the competition for resources available in the medium (Agostinetto et al, 2008). Chemical control with herbicide application is a commonly used method for suppression of these plant species (Lamego et al, 2013). Herbicide applications are recognized as causes of biological imbalance in agroecosystems (Guedes et al, 2015; Menezes and Soares, 2016). Selectivity is defined as the property that a pesticide presents to control a specific pest (weeds, insects, and diseases) with the least possible impact on its natural enemies in the agroecosystem under the same conditions in which the pest is controlled successfully (Castilhos et al, 2014)
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