Field evidence of bird poisonings by imidacloprid-treated seeds: a review of incidents reported by the French SAGIR network from 1995 to 2014

Abstract

The large-scale use of neonicotinoid insecticides has raised growing concerns about their potential adverse effects on farmland birds, and more generally on biodiversity. Imidacloprid, the first neonicotinoid commercialized, has been identified as posing a risk for seed-eating birds when it is used as seed treatment of some crops since the consumption of a few dressed seeds could cause mortality. But evidence of direct effects in the field is lacking. Here, we reviewed the 103 wildlife mortality incidents reported by the French SAGIR Network from 1995 to 2014, for which toxicological analyses detected imidacloprid residues. One hundred and one incidents totalling at least 734 dead animals were consistent with an agricultural use as seed treatment. Grey partridges (Perdix perdix) and “pigeons” (Columba palumbus, Columba livia and Columba oenas) were the main species found. More than 70% of incidents occurred during autumn cereal sowings. Furthermore, since there is no biomarker for diagnosing neonicotinoid poisonings, we developed a diagnostic approach to estimate the degree of certainty that these mortalities were due to imidacloprid poisoning. By this way, the probability that mortality was due to poisoning by imidacloprid-treated seeds was ranked as at least “likely” in 70% of incidents. As a result, this work provides clear evidence to risk managers that lethal effects due to the consumption by birds of imidacloprid-treated seeds regularly occur in the field. This in turn raises the question of the effectiveness of the two main factors (seed burying and imidacloprid-treated seeds avoidance) that are supposed to make the risk to birds negligible. Risk factors and the relevance of mitigation measures are discussed.Electronic supplementary materialThe online version of this article (doi:10.1007/s11356-016-8272-y) contains supplementary material, which is available to authorized users.

An update of the Worldwide Integrated Assessment (WIA) on systemic insecticides. Part 2: impacts on organisms and ecosystems

“…Millot et al (2015) reported that about 10% of the grey partridges found in their study fields that were exposed to thiacloprid, subsequently died, even though few direct impacts of other pesticides were detected. Finally, Millot et al (2017) suggested that in France, mortality due to poisoning by imidacloprid-treated seeds was at least likely in 70% of wildlife mortality incidents reported during 1994-2014. Lopez-Antia et al (2016 conclude that the use of pesticide-treated seeds presents an unacceptable risk to farmland birds.…”

“…One study estimated that the daily doses of insecticides ingested by red-legged partridges could cause sublethal (imidacloprid) or even lethal (fipronil) effects (Lopez-Antia et al 2016). A second concluded that mortality due to poisoning by imidacloprid-treated seeds was at least likely in 70% of reported wildlife mortality incidents (Millot et al 2017). Evidence of the indirect, food chain effects of these insecticides remains rare, though one correlative study found that some local populations of insectivorous birds declined more in areas with higher surface water concentrations of imidacloprid, possibly as a consequence of reduced invertebrate food supplies (Hallmann et al 2014).…”

Imidacloprid Poisoning of Songbirds Following a Drench Application of Trees in a Residential Neighborhood in California, USA

“…Aside from evidence of mild trauma, no other significant findings were observed during postmortem examination, and strychnine was not detected in digestive contents or liver tissues. Previous reports of imidacloprid-related mortality in birds have involved granivorous species and the ingestion of imidacloprid-treated seeds either during sowing or after accidental spills (Millot et al 2017). The route of exposure for the birds examined in the present study is likely ingestion of natural seeds contaminated during the drench application.…”

“…Previous reports of imidacloprid‐related mortality in birds have involved granivorous species and the ingestion of imidacloprid‐treated seeds either during sowing or after accidental spills (Millot et al ). The route of exposure for the birds examined in the present study is likely ingestion of natural seeds contaminated during the drench application.…”

“…Incidents of poisoning in free‐ranging birds have been most frequently documented following ingestion of imidacloprid‐treated seeds that remain on the soil surface after sowing or spillage (Millot et al ). Reported cases typically involve species of Galliformes and Columbiformes (Berny et al ; Millot et al ; Botha et al ), which have a tendency to ingest large quantities of seeds during a single bout of feeding. However, only 5 treated corn seeds, containing approximately 1 mg of active ingredient each, would be required to cause a potentially lethal dose for a 390‐g gray partridge ( Perdix perdix ; Goulson ).…”