Early life neonicotinoid exposure results in proximal benefits and ultimate carryover effects

Abstract

Neonicotinoids are insecticides widely used as seed treatments that appear to have multiple negative effects on birds at a diversity of biological scales. Adult birds exposed to a low dose of imidacloprid, one of the most commonly used neonicotinoids, presented reduced fat stores, delayed migration and potentially altered orientation. However, little is known on the effect of imidacloprid on birds growth rate despite studies that have documented disruptive effects of low imidacloprid doses on thyroid gland communication. We performed a $$2 \times 2$$ 2 × 2 factorial design experiment in Zebra finches, in which nestling birds were exposed to a very low dose (0.205 mg kg body $$\hbox {mass}^{-1}$$ mass - 1 ) of imidacloprid combined with food restriction during posthatch development. During the early developmental period, imidacloprid exposure resulted in an improvement of body condition index in treated nestlings relative to controls. Imidacloprid also led to compensatory growth in food restricted nestlings. This early life neonicotinoid exposure also carried over to adult age, with exposed birds showing higher lean mass and basal metabolic rate than controls at ages of 90–800 days. This study presents the first evidence that very low-dose neonicotinoid exposure during early life can permanently alter adult phenotype in birds.

Experimental Exposure to Tebuconazole Affects Metabolism and Body Condition in a Passerine Bird, the House Sparrow (Passer domesticus)

“…Several studies have demonstrated that contaminants can alter the functioning of the HPT axis and the metabolism of vertebrates (e.g., Braham & Neal, 1974), but most of these studies have focused on polychlorinated biphenyls (French et al, 2001; Smits et al, 2002; Tori & Mayer, 1981; Verreault et al, 2007; Voltura & French, 2000), organochlorine pesticides (Blévin et al, 2017), polybrominated diphenyl ethers (Allen et al, 2016; Lema Sean et al, 2008), per‐ and polyfluoroalkyl compounds (Ask et al, 2021; Blévin et al, 2017; Sebastiano et al, 2021), and neonicotinoids (Zgirski et al, 2021). The potential impact of endocrine disruptors on metabolism remains neglected, especially regarding contaminants of emerging interest such as azoles.…”