Analytical development for the assessment of pesticide contaminations in blood and plasma of wild birds: The case of grey partridges (Perdix perdix)

Biomonitoring of azole fungicides in free-living blackbird plasma using on-line solid-phase extraction coupled to liquid chromatography-tandem mass spectrometry (SPE HPLC-MS/MS)

In this study, a rapid and sensitive method using on-line solid-phase extraction (SPE) coupled to liquid chromatography - tandem mass spectrometry (SPE HPLC-MS/MS) was developed to analyse 15 azole fungicides currently used in vineyards in blackbird plasma samples. The monitored fungicides included 13 triazoles (cyproconazole, difenoconazole, epoxiconazole, fenbuconazole, flusilazole, flutriafol, metconazole, penconazole, propiconazole, tebuconazole, tetraconazole, triadimefon, triadimenol) and 2 imidazoles (imazalil and prochloraz). After a rapid preparation step by protein precipitation with acetonitrile on 25 µL of plasma samples, final extracts diluted with Milli-Q water were analyzed by on-line SPE-LC-MS/MS in positive electrospray mode (ESI+) using the dynamic multi-reaction monitoring mode (dMRM). Following optimization, method validation was achieved through studies of linearity, sensitivity, accuracy, precision, and sample extract conservation. The limits of quantification (LOQs) obtained for a low volume of plasma (25 µL) ranged from 0.01 to 0.43 ng g-1 plasma, except for triadimenol (1.37 ng g-1). Finally, the validated method was successfully applied to 34 Eurasian blackbird plasma samples, with blackbirds from different habitats (city, forest, vineyards) submitted to contrasted azole pressures. Five of them were detected, tebuconazole and tetraconazole being the predominant ones. As expected, azoles concentrations were more elevated in blackbirds sampled in vineyards where most of these fungicides are used.

Exposure to pesticides is correlated with gut microbiota alterations in a farmland raptor

The gut microbiota is crucial for host health and can be impacted by various environmental disruptions, yet the effects of multiple pesticide exposures on farmland organisms' microbiomes remain largely unexplored. We assessed microbiota changes in a wild apex predator exposed to multiple pesticides in agricultural landscapes. Pesticides, including acetochlor and quinoxyfen, which are supposed to be banned, were significantly positively correlated with certain key bacteria from Actinobacteria, Alphaproteobacteria and Gammaproteobacteria classes. Our results light up the potential collateral effect of pesticides on gut bacterial assemblages through unknown mechanisms. These effects could result in dysbiosis and the promotion of potential pathogens and/or the selection of bacteria that might allow the organism to detoxify the organism. Although formal metagenomic analyses would be required soon, these microbial shifts underline the broader ecological consequences of pesticide exposure, emphasising the need for integrated biodiversity conservation and ecosystem management to protect environmental and public health.

Direct and indirect effects of pesticide exposure on the gut microbiota of a farmland raptor

Recent studies in humans have shown that certain pesticides could affect the composition and functions of the gut microbiota, an essential modulator of vertebrate physiology, leading to potential dysbiosis. However, this relationship remains largely unknown in wild birds despite the implications of pesticides in the current decline of farmland species. The present study sought to fill this gap by providing data on the association between pesticide concentrations in blood and gut microbiota characteristics in relation to individual traits in a farmland raptor, the Montagu's harrier (Circus pygargus). Results showed that females with higher body condition and higher pesticide load exhibited greater gut bacterial richness and diversity, while the relationship was opposite in males with higher body condition. In terms of taxonomic composition, Proteobacteria emerged as the dominant phylum across all nestlings. Differences in the abundance of specific phyla and genera were observed according to pesticide load, with higher levels of Bacteroidota and Leifsonia, but lower levels of Bulkholderia, in nestlings with higher pesticide concentrations in their blood. This study highlights differences in microbiota and contamination by several pesticides according to the phenotypic characteristics of a wild raptor, and shows that farmland birds can represent relevant biosentinels for assessing the health/proper functioning of ecosystems (One Health approach).

An in-depth analysis of the effects of excessive acetochlor exposure on chicken liver health

Acetochlor, a commonly used herbicide, poses significant risks to ecosystem and organism health through contamination of the food chain. Despite its widespread use, there is a lack of comprehensive studies on its toxicological effects on avian species. This study investigates the impact of environmental acetochlor exposure on chicken liver health using metabolomics analysis and histopathological techniques. Microscopic examination revealed autophagy-like structures and endoplasmic reticulum (ER) expansion, with significant effects observed at higher exposure levels. Biochemical analysis and metabolomics also demonstrated acetochlor-induced ferroptosis, highlighting disruptions in liver function. Further, in vitro studies revealed that acetochlor stimulates autophagy, which regulates ferroptosis via ferritin degradation, mediated through the ER-CaMKII pathway. These findings emphasize the importance of understanding the molecular mechanisms involved in acetochlor toxicity, particularly the role of the Ca2+/CaMKII pathway, ER stress, and autophagy in ferroptosis. The study contributes to a deeper understanding of how environmental contaminants affect avian species, providing critical insights for better herbicide risk assessment, pollution control, and sustainable agricultural practices.

First evidence of age-dependent decreases in non-persistent pesticide mixtures in nestlings of a farmland raptor

Intensive use of synthetic pesticides in conventional agriculture may harm non-target organisms through sublethal effects on life-history traits. Farmland birds are exposed throughout their life cycle, but the fate of non-persistent pesticide mixtures in wild birds remains unknown. In this study, we investigated changes in pesticide contamination levels in Montagu's harrier (Circus pygargus) nestlings during their growth. In total, 35 chicks were sampled twice during the rearing period, and blood was tested for 116 pesticides to assess pesticide load through two proxies; the number of pesticides detected and the sum of pesticide concentrations. Body mass and tarsus length were also measured to estimate body condition. Across the two sampling times, nine herbicides, five insecticides and four fungicides were detected. Contamination levels decreased significantly with nestling age irrespective of sampling date, and there was no relationship between pesticide load and body condition. Moreover, concentrations of chlorpyrifos-methyl, fenpropidin, metamitron, picloram and S-metolachlor, all detected throughout the rearing period, were unrelated to any of the explanatory variables. However, ethofumesate concentrations decreased significantly with chick age. This study provides the first evidence that non-persistent pesticide mixtures can decrease with age in wild nestlings. This has implications for understanding how chicks are contaminated and provides new insights on pesticide fate within organisms.

Development and validation of a multi-substance method for routine analysis of pesticides in post-mortem samples by Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry

Pesticides play an important role in forensic toxicology and are usually classified as a single class of chemicals. Despite their commonly perceived unity, pesticides encompass a spectrum of compounds, including organophosphates, carbamates, pyrethroids or organochlorines, among others, each with varying degrees of toxicity. Pesticide analysis in post-mortem samples can be difficult due to the complexity of the samples and to the high toxicity of these compounds. The aim of this study was to develop and validate an easy to use, sensitive, and robust method, using ultra-performance liquid chromatography-tandem mass spectrometry to be incorporated in the routine flow for pesticide analysis in post-mortem blood samples. Described herein is a streamlined, expeditious, yet highly efficient method facilitating the screening, qualitative assessment, and quantitative confirmation of 15 pesticides, including acetamiprid, azinphos-ethyl, bendiocarb, carbofuran, chlorfenvinphos, dimethoate, imidaclopride, malathion, methiocarb, methomyl, parathion, pirimicarb, strychnine, tetrachlorvinphos, and thiacloprid in post-mortem blood, recognizing the pivotal role blood plays in forensic investigations. The developed method was linear from 10 to 200 ng/mL; limits of detection were between 1 and 10 ng/mL, depending on the compound; it was successfully evaluated a dilution ratio of 1-2, 5 and 10; and 8 substances showed maximum stability for the time interval studied. This UHPLC-MS/MS method is useful and a powerful tool in a toxicology lab because it is fast, simple, effective, and trustworthy. The results of this validation highlight the robustness of the analytical method, providing a valuable tool for the accurate and sensitive detection of pesticides in post-mortem blood. Poised for routine implementation, this method has already found success in suspected intoxication cases, promising to elevate the standards of forensic pesticide analysis.

Organic farming reduces pesticide load in a bird of prey

Human activities have led to the contamination of all environmental compartments worldwide, including bird species. In birds, both the environment and maternal transfer lead to high inter-brood variability in contamination levels of pollutants, whereas intra-brood variability is generally low. However, most existing studies focused on heavy metals or persistent compounds and none, to our knowledge, addressed the variability in contamination levels of multiple pesticides and the factors influencing it. In this study, the number of pesticides detected (of 104 compounds searched) and the sum of their concentrations in the blood of 55 Montagu's harrier (Circus pygargus) nestlings from 22 nests sampled in 2021 were used as metrics of contamination levels. We investigated the effect of organic farming at the size of male's home range (i.e., 14 km2) and chicks' sex and hatching order on contamination levels. We did not find a difference between inter-brood and intra-brood variability in pesticide contamination levels, suggesting a different exposure of siblings through food items. While chicks' sex or rank did not affect their contamination level, we found that the percentage of organic farming around the nests significantly decreased the number of pesticides detected, although it did not decrease the total concentrations. This finding highlights the potential role of organic farming in reducing the exposure of birds to a pesticide cocktail.

Optimization and uncertainty assessment of a gas chromatography coupled to Orbitrap mass spectrometry method to determine organic contaminants in blood: A case study of an endangered seabird

Birds are excellent bioindicators of environmental pollution, and blood provides information on contaminant exposure, although its analysis is challenging because of the low volumes that can be sampled. The objective of the present study was to optimize and validate a miniaturized and functional extraction and analytical method based on gas chromatography coupled to Orbitrap mass spectrometry (GCOrbitrap-MS) for the trace analysis of contaminants in avian blood. Studied compounds included 25 organochlorine pesticides (OCPs), 6 polychlorinated biphenyls (PCBs), 8 polybrominated diphenyl ethers (PBDEs) and 15 polycyclic aromatic hydrocarbons (PAHs). Four extraction and clean-up conditions were optimized and compared in terms of efficiency, accuracy, and uncertainty assessment. Extraction with hexane:dichloromethane and miniaturized Florisil pipette clean-up was the most adequate considering precision and accuracy, time, and costs, and was thereafter used to analyse 20 blood samples of a pelagic seabird, namely the Bermuda petrel (Pterodroma cahow). This species, endemic to the Northwest Atlantic, is among the most endangered seabirds of the region that in the '60 faced a decrease in the breeding success likely linked to a consistent exposure to dichloro-diphenyl-trichloroethane (DDT). Indeed, p,p'-DDE, the main DDT metabolite, was detected in all samples and ranged bewteen 1.13 and 6.87 ng/g wet weight. Other ubiquitous compounds were PCBs (ranging from 0.13 to 6.76 ng/g ww), hexachlorobenzene, and mirex, while PAHs were sporadically detected at low concentrations, and PBDEs were not present. Overall, the extraction method herein proposed allowed analysing very small blood volumes (∼ 100 µL), thus respecting ethical principles prioritising the application of less-invasive sampling protocols, fundamental when studying threatened avian species.

Pesticides in small volume plasma samples: Method development and application to smallmouth bass (Micropterus dolomieu) from the Chesapeake Bay watershed, USA

Nontarget organisms are exposed to pesticides following applications in agricultural and urban settings, potentially resulting in deleterious effects. Direct measurements of pesticides in biological tissues may aid in characterizing exposure, accumulation, and potential toxicity versus analyses in environmental media alone (e.g., water, soil, and air). Plasma represents a nonlethal sampling medium that can be used to assess recent exposures to contaminants. Herein, a method was developed to test the extraction of 210 pesticides and their transformation products in small volume plasma samples (100 μL). Plasma samples were protein precipitated with 0.5 % formic acid in acetonitrile added to the sample (ratio of 3.5:1). Pass-through solid phase extraction was used for sample matrix and lipid removal and samples were analyzed by liquid chromatography and gas chromatography with tandem mass spectrometry. Recoveries of 70.0-129.8 % were achieved for 182 pesticides and degradates across the low (25 ng mL-1), medium (100 ng mL-1), and high (250 ng mL-1) spike levels. Method detection levels ranged 0.4-13.0 ng mL-1. Following development, the method was applied to smallmouth bass (Micropterus dolomieu) plasma samples (n = 10) collected from adults in the Chesapeake Bay watershed. Individual plasma samples resulted in four to seven analytes detected with summed concentrations ranging 16.4-95.0 ng mL-1. Biological multiresidue pesticide methods help elucidate recent exposures of bioactive compounds to nontarget organisms.

Neonicotinoids: Still present in farmland birds despite their ban

Neonicotinoids (neonics) are the most widely used insecticides worldwide and are considered to be of low risk to non-target organisms such as vertebrates. Further, they are reported to be rapidly excreted and metabolized, reducing their potential toxicity. Nevertheless, growing evidence of adverse effects of neonics on farmland bird species raise questions about the purported harmless nature of these pesticides. We attempted to search for pesticide residues in species of different trophic levels and at different life stages, by using multiple bird monitoring programs on a Long-Term Socio-Ecological Research (LTSER) platform. Three passerine birds-the blackbird (Turdus merula), cirl bunting (Emberiza cirlus), and common nightingale (Luscinia megarhynchos)-that feed on seeds and invertebrates were monitored during their reproductive period, and the grey partridge (Perdix perdix) that feeds on seeds was monitored during its wintering period. We also monitored chicks of an apex predator-the Montagu's harrier (Circus pygargus)-that preys mostly upon common voles but also upon insects. We found that the birds' blood samples showed presence of residues of five neonics: three banned since 2018 in France-clothianidin, thiacloprid, and thiamethoxam-and two-dinotefuran and nitenpyram-used for veterinary purposes only. While none of these neonics was detected in blackbirds, all were present in grey partridges. Clothianidin was detected in all species, except blackbirds. Concentrations of the three banned neonics were similar or higher than concentrations found in birds monitored elsewhere before the ban. These findings raise questions about the persistence of neonics within the environment and the mode of exposure to wild fauna. Future investigations on the sublethal effects of these neonics on life-history traits of these farmland birds may help in providing a better understanding of the effects of exposure of bird populations to these insecticides, and also to the consequent effect on human health.