Analytical confirmation of imidacloprid poisoning in granivorous Cape spurfowl (Pternistis capensis)

Abstract

Reports were received that Cape spurfowl (Pternistis capensis) fell during flight and scrambled uncoordinatedly for cover and some died. Three carcases were submitted for necropsy examination, which revealed mainly congestion of the carcases and haemorrhages. Common causes of acute mortalities in birds were first excluded, but there was a history of possible exposure to imidacloprid-treated barley seeds. Imidacloprid, a neonicotinoid insecticide, is used to protect various crops against invertebrate pests. The combined crop contents and pooled liver samples collected from the Cape spurfowl during necropsy were submitted for liquid chromatography–high-resolution mass spectrometry (LC-HRMS) for imidacloprid analysis. Imidacloprid and several of its metabolites were detected in the samples. Farmers should cover sown seeds with a layer of soil and remove any spilled seeds, as granivorous birds are susceptible to imidacloprid intoxication. Regulatory authorities should re-evaluate the risk posed by imidacloprid-treated seeds for pollinators and granivorous birds.

Sublethal and Lethal Methods to Detect Recent Imidacloprid Exposure in Birds with Application to Field Studies

“…Our dosing levels were comparable, bracketing their levels of 0.9 and 2.7 mg/kg for 1 or 10 d, so the most likely cause for the discrepancy is that our analytical approach was 10-fold more sensitive. Yet, it is possible that toxicokinetics in quail differs from that in chickens and other birds (Millot et al 2017;Botha et al 2018;Bean et al 2019) or that empirical toxicokinetics differs between pure compounds (present study) and commercial formulations (Bean et al 2019). Imidacloprid residues ranging 0 to >300 ng/g (average 82.6 + 22.5 ng/g during exposure days 5-21) have also been reported in livers of dosed red-legged partridges (Alectoris rufa) after 5 to 21 d of exposure to 44 mg/kg/d (Lopez-Antia et al 2015; LOD of 5 ng/g, LOQ of 16.4 ng/g).…”

“…Residues of imidacloprid have been detected in livers of pigeon (Columba spp., 1.4 μg imidacloprid/g wet wt) and gray partridge (Perdix perdix, 3.0 μg imidacloprid/g wet wt) in France (LOD 0.1 μg/g; Millot et al 2017), in Cape spurfowl (Pternistis capensis) from South Africa (16-29 ng imidacloprid/g wet wt; Botha et al 2018), and in northern bobwhite (Colinus virginianus) in the United States, although detections were <LOQ (2.80 μg/kg, with LOD 30% lower; Ertl et al 2018). More sensitive assays, like ours, allow for longer durations of detection; but exposure dose and time since exposure will continue to be difficult to determine in field-collected samples, complicating interpretation about exposure and toxicological effects.…”

“…Carcasses may also be inconspicuous (de Snoo et al 1999) and can be quickly scavenged and not completely recovered (Vyas 1999). Despite these challenges, some neonicotinoid poisoning incidents have been detected in the wild (Berny et al 1999;de Snoo et al 1999;Millot et al 2017;Botha et al 2018;Rogers et al 2019). In France, over 100 incidents were reported through a national epidemiological surveillance network between 1995 and 2014 and mostly involved pigeons and partridges but also involved cranes, gulls, starlings, and pheasants (Millot et al 2017).…”

“…In addition, immune suppression has been measured in both adults and chicks (Lopez-Antia et al 2013. Sublethal effects that might be associated with reduced survival include hyporeactivity, wing drop, immobility, lack of coordination, or inability to fly (Goulson 2013;Gibbons et al 2014;Botha et al 2018). Such effects in wild birds would be expected to reduce the ability of birds to escape predators and forage competently.…”

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

“…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 ).…”