Birds are potentially exposed to neonicotinoid insecticides by ingestion of coated seeds during crop planting. Adult male Japanese quail were orally dosed with wheat seeds coated with an imidacloprid (IMI) formulation at either 0.9 or 2.7 mg/kg body weight (BW) (∼3 and 9% of IMI LD50 for Japanese quail, respectively) for 1 or 10 days. Quail were euthanized between 1 and 24 h postexposure to assess toxicokinetics. Analysis revealed rapid absorption (1 h) into blood and distribution to the brain, muscle, kidney, and liver. Clearance to below detection limits occurred at both dose levels and exposure durations in all tissues within 24 h. Metabolism was extensive, with 5-OH-IMI and IMI-olefin detected at greater concentrations than IMI in tissues and fecal samples. There was no lethality or overt signs of toxicity at either dose level. Furthermore, no evidence of enhanced expression of mRNA genes associated with hepatic xenobiotic metabolism, oxidative DNA damage, or alterations in concentrations of corticosterone and thyroid hormones was observed. Application of the toxicokinetic data was used to predict IMI residue levels in the liver with reasonable results for some field exposure and avian mortality events. It would appear that some affected species of birds are either consuming larger quantities of seeds or exhibit differences in ADME or sensitivity than predicted by read-across from these data.

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Polymerase chain reaction (PCR)-based methods to determine the sex of birds are well established and have seen few modifications since they were first introduced in the 1990s. Although these methods allowed for sex determination in species that were previously difficult to analyse, they were not conducive to high-throughput analysis because of the laboriousness of DNA extraction and gel electrophoresis. We developed a high-throughput real-time PCR-based method for analysis of sex in birds, which uses noninvasive sample collection and avoids DNA extraction and gel electrophoresis.

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