Fonofos poisons raptors and waterfowl several months after granular application

Science and Technology Branch, Environment Canada, Pacific Wildlife Research Centre, Delta, BC, Canada.
Environmental Toxicology and Chemistry (Impact Factor: 3.23). 03/2008; 27(2):452-60. DOI: 10.1897/07-178R.1
Source: PubMed


From 1994 to 1999 in the Lower Fraser Valley region of southwest Canada, fonofos (Dyfonate G) was recommended for control of introduced wireworm (Agriotes spp.) pests on potato and other root crops. As part of a wildlife-monitoring program, we collected 15 raptors, including 12 bald eagles (Haliaeetus leucocephalus), found dead or debilitated on or near agricultural lands with severely inhibited brain and/or plasma cholinesterase activity and fonofos residues in ingesta. Bird remains, in nine cases waterfowl, were identified in the ingesta samples. Another seven bald eagles had severe cholinesterase inhibition, but without evidence of fonofos residues. During two winters from 1996 to 1998, 420 ha of potato fields, half of which had been treated the previous spring with fonofos and the remainder untreated, were searched weekly for evidence of wildlife mortality. Search efficiency was assessed with placed duck carcasses. Waterfowl outnumbered other species in field-use counts and comprised the greatest proportion of birds found dead. We found 211 wildlife remains, most scavenged; 35 intact carcasses were suitable for postmortem examination and/or toxicology analyses. Cholinesterase activity was assayed in brains of 18 waterfowl, five of which had severely depressed activity (average inhibition 74%; range, 69-78%). The gastrointestinal tract of a mallard found in a field treated with granular product contained 49 microg/g fonofos residues, linking waterfowl mortality with labelled use of the product. These findings demonstrate the risk of both primary and secondary poisoning by anticholinesterase insecticides where wildlife make intensive use of farmed fields.

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    • "The intent of this study was to include barn owls at wildlife rehabilitation centers that were exhibiting signs of AR toxicity, such as with testing for anticholinesterase poisoning (e.g. Elliott et al. 2008) or lead (Elliott et al. 1992). However, during the length of the study, a sample was obtained from only one individual presented to the partner rehabilitation centre with these symptoms (see Fig. 9). "
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    • "Because pesticide toxicity to wildlife is not fully tested prior to approval for agricultural purposes, some pesticides are slow to be removed from market despite evidence indicating their potential negative impacts on wildlife species. Fonofos was discontinued in 1999 as a result of its toxicity to raptors and waterfowl, for example, yet at the time, three out of seven pesticides known to cause avian mortality remained in use (Flickinger et al. 1991; Hunt et al. 1991; Mineau et al. 2005; Elliott et al. 2008). When pesticides leach into nearby streams and ponds they can be lethal for aquatic species, sometimes in ways that escape detection under controlled experimental conditions. "
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