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Glance on the role of detoxification enzymes in resistance mechanism
of Cowpea aphid ( Aphis craccivora Koch) to thiamethoxam
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Abstract: Cowpea aphid (Aphis craccivora Koch) is considered a serious insect pest attacking several crops. As result of intensive used of insecticides, A. craccivora has developed resistance to various insecticides. Therefore, in the present study, biochemical studies were carried out to elucidate the mechanisms of resistance in Cowpea aphid to thiamethoxam. The thiamethoxam resistant strain showed 48 fold resistance after selection pressure with thiamethoxam for 12 generations.
Bioassay test revealed that the resistant strain also exhibited cross resistance to the tested carbamate insecticides; pirimicarb and carbosulfan. While showed vigor tolerance ratio to organophosphorus insecticide; malathion and low tolerance level to fenitrothion and chlorpyrifos- methyl. High vigor tolerance was also obtained to neonicotinoid ; acetamiprid. Synergism studies pointed out that DEF as a remarkable inhibitor for esterases in insects, increased thiamethoxam toxicity to R strain 5.58 times. Moreover, biochemical assays revealed that carboxylestersae activity was 30 times higher in the R strain than that in S strain. Determination of AChE activity showed that R strain had 3.68 times higher activity compared to the susceptible strain. Generally, our result suggest that the higher activity of the detoxification enzymes namely esterases is likely a resistance mechanism to thiamethoxam in Cowpea aphid.
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| Publication year |
2015
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Journal
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