Neonicotinoid exposure in Tricolored Blackbirds (Agelaius tricolor)

Abstract

There is increasing awareness of the negative ecological and environmental effects of widespread use of pesticides on the landscape. Spillover or drift of pesticides from agricultural areas has been shown to impact species health, reproduction, and trophic dynamics through both direct and indirect mechanisms. Neonicotinoid insecticides are associated with observed declines of insectivorous and grassland birds, and these environmental pollutants are a significant conservation concern for many species that have experienced past or current population declines. Due to the high efficacy of these modern insecticides in depressing local insect populations, insectivorous birds can be negatively impacted by a pesticide-mediated reduction in food supply. Neonicotinoids may act synergistically with other stressors, such as habitat loss, to exacerbate threats to species or population viability. The Tricolored Blackbird is an insectivorous grassland bird of conservation concern in California, USA. Due to the high association of this species with agricultural habitats, we sought to quantify the amount of neonicotinoid residues in Tricolored Blackbird carcasses as a first step in assessing how this species may be impacted by pesticides. Out of 85 salvaged carcasses sampled (N = 24 adults, N = 3 fledglings, and N = 58 nestlings), only two contained detectable levels of target compounds. These were an adult and one nestling that contained clothianidin residue (40 ppb and 7 ppb, respectively); both of these birds were salvaged from breeding colonies associated with dairy farms in Kern County, California. We suggest that further work is needed to assess neonicotinoid exposure of Tricolored Blackbirds in dairy-associated breeding colonies.

Status Report on Neonicotinoid Pollution in Japan: Emphasis on Human, Animal, and Environmental Health

“…Status of Neonicotinoid Pollution in Japan 2018; Takeuchi and Nishizawa, 2018;Nishino et al, 2018;Yamamuro et al, 2019;Graves et al, 2023). Moreover, a couple of biomonitoring studies have consistently reported neonicotinoids in humans and other nontarget vertebrates (Ueyama et al, 2015;Harada et al, 2016;Kabata et al, 2016;Osaka et al, 2016;Honda et al, 2019;Ikenaka et al, 2019;Ospina et al, 2019;Tao et al, 2019a;Tao et al, 2019b;Zhang et al, 2019b;Li and Kannan, 2020;Li et al, 2020c;Song et al, 2020;Wang, et al, 2020a;Nimako et al, 2021;Oya et al, 2021;Taira et al, 2021;Nimako et al, 2022;Shinya et al, 2022).…”

“…At present, reports of massive consumption rates and high environmental ubiquity of neonicotinoid-containing formulations have sparked several concerns about their potential adverse effects on biodiversity. These concerns are justified as neonicotinoid spillovers or drifts from agricultural areas could contaminate various ecological habitats and pose risks to species' populations, health, reproduction, and trophic dynamics (Graves et al, 2023).…”

“…Neonicotinoid insecticide applications are strongly associated with recent declines in insectivorous and grassland bird populations, generating serious conservation concerns for many globally endangered species (Graves et al, 2023). Neonicotinoids may elicit adverse effects directly or indirectly.…”

“…The decline was most eminent in grassland and insectivorous birds, which recorded mean annual reduction rates of 4% and 3%, respectively. Graves et al (2023) detected clothianidin residue in the carcasses of Environmental Monitoring and Contaminants Research Vol.3, pp.69 -91 (2023) an adult and nestling Tricolored Blackbird (40 and 7 ng / mL) from breeding colonies in Kern County, California, US. These findings collectively suggest that different avian species could be exposed to various neonicotinoids and hence may be susceptible to the adverse outcomes of these compounds.…”