Chlorpyrifos: exposure and effects in passerines and anurans

Chlorpyrifos exposure and effects in passerines and anurans were examined in a series of experiments. European starling Sturnus vulgaris) nestlings were used as a surrogate to study the effect of chlorpyrifos application to a com acroecosystem on songbird reproduction. Chlorpyrifos was applied in a T-band at label rates; residues were measured in soil, earthworms, ground-dwelling insects, and diet items collected from the crop of starling nestlings. Chlorpyrifos was detected in all matrices. Nestling brain and plasma cholinesterase (ChE) activity and body mass measurements were taken at 3, 8, and 13 days post-hatch (DPH). There were no significant differences in reference vs. treatment brain or plasma ChE activities of 3, 8, or 13 DPH nestlings. Body mass differences between treatment and reference site nestlings at 3 and 13 DPA were not significant (a = 0.05). However, 8 DPH nestlings from the treatment site had a transient reduction in weight (p = 0.03) when compared with 8 DPH reference nestlings. Adult starling fecundity measures (i.e., clutch size, hatching percentage, and fledging percentage) indicated that chlorpyrifos application did not significantly affect starling nestling survival to fledging. This screening-level study suggests that although one age group of starling nestlings from the treatment site weighed less than their reference site counterparts, a single T-band application of chlorpyrifos did not impair starling nesting success.