Survey and Risk Assessment of Apis mellifera (Hymenoptera: Apidae) Exposure to Neonicotinoid Pesticides in Urban, Rural, and Agricultural Settings.

A comparative assessment of apiaries in urban, rural, and agricultural areas was undertaken in 2013 and 2014 to examine potential honey bee colony exposure to neonicotinoid insecticides from pollen foraging. Apiaries ranged in size from one to hundreds of honey bee colonies, and included those operated by commercial, sideline (semicommercial), and hobbyist beekeepers. Residues in and on wax and beebread (stored pollen in the hive) were evaluated for the nitro-substituted neonicotinoid insecticides imidacloprid and its olefin metabolite and the active ingredients clothianidin, thiamethoxam, and dinotefuran. Beebread and comb wax collected from hives in agricultural landscapes were more likely to have detectable residues of thiamethoxam and clothianidin than that collected from hives in rural or urban areas (∼50% of samples vs. <10%). The maximum neonicotinoid residue detected in either wax or beebread was 3.9 ppb imidacloprid. A probabilistic risk assessment was conducted on the residues recovered from beebread in apiaries located in commercial, urban, and rural landscapes. The calculated risk quotient based on a dietary no observable adverse effect concentration (NOAEC) suggested low potential for negative effects on bee behavior or colony health.

Bioremediating herbicide-contaminated soils.

Combinations of landfarming and biostimulation were evaluated for remediating pesticide wastes. Various amounts of soil contaminated with alachlor and trifluralin (> or = 100 mg/kg each) and metolachlor and atrazine (> or = 20 mg/kg each) were applied to field plots, and sewage sludge or corn meal was incorporated into designated plots. Plots were also treated with fresh spray mixtures in amounts similar to those applied as contaminated soil. Soil bioactivity and dissipation of parent herbicides were monitored after the treatments. During 100 d, soil dehydrogenase activities were highest in organic-material-amended plots. During the same period, the levels of alachlor had declined by 85-95% in amended, contaminated soil-treated plots and by 75-85% in corresponding unamended plots. In freshly sprayed plots, 95-100% of the initial doses of alachlor had dissipated in amended plots, and 85-95% was lost in corresponding unamended plots. The levels of trifluralin had declined by 70-80% in corn-meal-amended plots and by 60-75% in unamended plots. There were no significant differences between dissipation of trifluralin applied as contaminated soil or fresh sprays.