Evaluation of the use of the inhibition esterases activity on Apis mellifera as bioindicators of insecticide thiamethoxam pesticide residues

A trial was carried out to estimate the LC50 and esterase activity of Apis mellifera L. honeybees after the application of the insecticide thiamethoxam. In insects this product mimics acetylcholine at the central system ganglia. The estimated LC50 were as follows: for oral toxicity: 4.70 x 10(-5), 7.40 x 10(-5), 8.14 x 10(-5), 10.10 x 10(-5) mg/mL for the ages of newly emerged, 7, 14 and 21 days, respectively; for contact toxicity, 3.21, 3.50 and 4.51 mg/mL for newly emerged individuals and for the ages of seven and 14 days, respectively. Electrophoretic analysis showed a decrease in the activity of esterases 1, 2, 4 and 5 due to contact and oral toxicity, suggesting that alteration in the activity of those isozymes can be used to detect the presence of insecticide thiamethoxam pesticide residues.