The first study, with results published in March, showed that white-tailed deer with high levels of neonicotinoid pesticide in their spleens developed defects such as smaller reproductive organs, pronounced overbites and declined thyroid function. Fawns with elevated levels of the pesticide in their spleens were found to be generally smaller and less healthy than deer with less of the chemical in their organs. The study marks the first time neonicotinoid pesticide consumption has been linked to birth defects in large mammals.
“These (neonicotinoids) were deemed to be safe for higher organisms, and the fact that we saw so many diverse impacts on white-tailed deer, that was a big thing,” said Dr. Jonathan Lundgren an ecologist from Estelline, S.D., an independent scientist who co-authored the study. “And then, the fact that whitetail deer are not that far off from our livestock or even humans suggests that maybe we need to be examining these insecticides’ risks a little bit more closely” [Nick Lowrey, “SDSU Study Shows World’s Most Common Pesticide a Danger to Deer,” South Dakota News Watch, 2019.10.16].
The levels of imidacloprid, one type of neonicotinoid that the European Union severely restricted in 2013 and banned for outdoor use in 2018, to which the SDSU researchers subjected their lab deer may be lower than what deer in the wild are ingesting:
The SDSU study also examined spleen samples from more than 360 wild deer killed by cars, poachers or disease in North Dakota, Jenks said. Those samples provided one of the study’s biggest surprises and most significant findings. The wild North Dakota deer, on average, showed neonicotinoid concentrations 3.5 times higher in their spleens than even the captive deer to which Jenks, Lundgren and their fellow researchers gave what they believed to be extremely high doses of imidacloprid [Lowrey, 2019.10.16].
The SDSU researchers have a paper on neonicotinoid effects on pheasants in the publication chute. Perhaps our pheasant-fanatic Governor will want to keep an eye our for that paper and incorporate its findings in the next phase of her bird-boosting initiative.