Toxicity, survivability, and activity patterns of northern bobwhite quail dosed with the insecticide terbufos

The effects of the organophosphorus insecticide terbufos on laboratory-reared and wild northern bobwhites (Colinus virginianus) were investigated in laboratory dosing studies and dose-release field trials. Laboratory studies yielded a terbufos LD50 of 24.4 mg/kg-body weight (bw). All mortalities occurred within the first 24 h post-dose. Wild bobwhites were trapped, administered 0, 3, 5.6, or 21 mg/kg-bw terbufos by oral intubation, released at their trapping site, and monitored for 14 d. Mortality, activity, and locational data were recorded. Bobwhites treated with 21 mg/kg-bw terbufos had significantly lower survival (p = 0.04) than control birds, while survival at the lower doses was unaffected. No significant differences (p = 0.06) were detected in physical activity among treatments. The 21-mg/kg-bw dose yields an anticipated 37% mortality (or LD37) when interpolated from the LD50 slope equation. After adjustment for control mortality, the 21-mg/kg-bw dose led to 44% mortality in wild bobwhites. This was a 7% higher mortality than predicted by interpolation from the laboratory generated LD50. These results indicate that there was not a substantial increase in mortality of wild bobwhites compared to laboratory-reared bobwhites at nonlethal or lethal, sub-LD50, doses.