Dissipation kinetics of imidacloprid in cotton flower, nectariferous tissue, pollen and Apis mellifera products using QuEChERS method.

Background: Exposure of Apis mellifera to neonicotinoid insecticides is one of the factors attributed to the recent decline in A. mellifera populations resulting in economic and ecological losses due to loss of pollination services. Honey bees can get exposed to neonicotinoids like imidacloprid directly in the field at the time of application as well as during consumption of pollen and nectar from treated plants. So, the fate of imidacloprid in commodities to which honey bees get exposed needs to be overhauled.

Results: Residue of imidacloprid was investigated following imidacloprid application as seed treatment (2.4 and 4.8 g a.i. kg seed) at the time of sowing and as foliar spray (17.8 and 35.6 g a.i. ha ) at 70 days after sowing when the crop was at full bloom stage.  The imidacloprid residue was below limit of quantification (LOQ) in flowers, necatariferous tissue, pollen from seed-treated cotton plants and honey collected from hives kept in plots with seed-treated cotton plants. However, average initial imidacloprid residue (2 h after spray) was 1.84 and 1.95 mg kg in flowers; 0.22 and 0.24 mg kg in nectariferous tissue; 0.88 and 0.96 mg kg in pollen collected from plants sprayed with imidacloprid @ 17.8 g a.i. ha at locations Faridkot and Bathinda, respectively. The average initial imidacloprid residue (21 days after spray) in honey collected from hives was 0.01 mg kg .

Conclusion: The residue in different substrates sampled from seed treated cotton plants was below LOQ. However, its foliar spray at bloom time resulted in imidacloprid residue in flower, nectariferous tissue, pollen and honey sampled from hives placed in plots. © 2021 Society of Chemical Industry.