| Abstrakt: |
Sitophilus oryzae and Sitophilus zeamais are among the main pests of stored grains worldwide, they are very similar species and have great destructive potential, causing numerous damages to grain production. The control of these insects occurs, in general, through chemical insecticides such as the agrochemicals pirimiphos-methyl, an organophosphate, and bifenthrin, a pyrethroid, which are widely used to prevent infestation. Four strains of these two species were exposed to the two classes of agrochemicals mentioned. The polyacrylamide gel electrophoresis technique was used to identify the esterase patterns of the species and eight esterases were identified for S. zeamais, of which four cholinesterases, two carboxylesterases, one acetylesterase, and one arylesterase; and seven esterases for S. oryzae, being four cholinesterases, two carboxylesterases, and one acetylesterase. After exposure to agrochemicals, through dose-response bioassays, the LC50 was determined for each strain, with the SoB strain of S. oryzae being the most resistant to bifenthrin, the SzB strain of S. zeamais being the most resistant to pirimiphos-methyl and the SoA strain of S. oryzae was the most sensitive to both compounds. Analysis of the esterase patterns of insects exposed to these agrochemicals revealed the inhibition and probable involvement of carboxylesterases and cholinesterases in the detoxification processes of organophosphates and pyrethroids. [ABSTRACT FROM AUTHOR] |
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