Individual quality overwrites carry-over effects across the annual cycle of a long-distance migrant.

In seasonal environments, the fitness of animals depends upon the successful integration of life-history stages throughout their annual cycle. Failing to do so can lead to negative carry-over effects where individuals are transitioning into the next season in different states, consequently affecting their future performance. However, carry-over effects can be masked by individual quality when individuals vary in their efficiency at acquiring resources year after year (i.e. 'quality'), leading to cross-seasonal consistency in individual performance. Here we investigated the relative importance of carry-over effects and individual quality in determining cross-seasonal interactions and consequences for breeding success over the full annual cycle of a migratory seabird (black-legged kittiwake Rissa tridactyla). We monitored the reproduction and annual movement of kittiwakes over 13 years using geolocators to estimate their breeding success, distribution and winter energy expenditure. We combined this with an experimental approach (clutch removal experiment, 2 years) to manipulate the reproductive effort irrespective of individual quality. Piecewise path analyses showed that successful breeders reproduced earlier and were more likely to breed successfully again the following year. This positive interaction among consecutive breeding stages disappeared after controlling for individual quality, suggesting that quality was dominant in determining seasonal interactions. Moreover, controlling experimentally for individual quality revealed underlying carry-over effects that were otherwise masked by quality, with breeding costs paid in higher energy expenditure and delayed onset of reproduction. We highlight the need to combine an experimental approach along with long-term data while assessing apparent carry-over effects in wild animals, and their potential impact on fitness and population demography.

Pesticide concentrations in a threatened freshwater turtle (Emys orbicularis): Seasonal and annual variation in the Camargue wetland, France.

Wetlands are among the most threatened ecosystems on the planet and pollution is a major factor causing the decline of wetland biodiversity. Despite the increasing use of pesticides, their fate and effects on freshwater reptiles remain largely unknown. We studied the European pond turtle (Emys orbicularis), a long-lived species at risk with a high exposure potential to pesticides. Between 2018 and 2020, we measured 29 pesticides and metabolites in 408 blood samples of turtles from two populations in the Camargue wetland (France). We were able to quantify 24 compounds and at least one pesticide or one degradation product in 62.5% of samples. Pesticide occurrences and concentrations were low, except for a herbicide widely used in rice cultivation and locally detected in water: bentazone that reached high blood concentrations in E. orbicularis. The occurrence and the concentration of pesticides in E. orbicularis blood depended mainly on the site and the sampling date in relation to pesticide application. Individual characteristics (sex, age, body condition) did not explain the occurrence or the concentration of pesticides found in turtle blood. Assessing the exposure of aquatic wildlife to a cocktail of currently-used pesticides is a first and crucial step before studying their effects at the individual and population levels.

Wild fish from a highly urbanized river (Orge, France) as vectors of culturable Enterobacterales resistant to antibiotics.

This study shows how wild fishes from urbanized rivers could be involved in the spread of antibiotic-resistant Enterobacterales. Antibiotic resistance profiles and molecular detection of clinical integron (IntI1) were carried out on 105 Enterobacterales isolated from 89 wildfish (skin or gut) belonging to 8 species. The proportion of isolates resistant to at least one antibiotic was independent of fish species and reached 28.3% within the Escherichia coli (E. coli) population and 84.7% in the non-E.coli Enterobacterales. Bacteria involved in nosocomial infections were isolated, such as E. coli, Klebsiella, and Enterobacter, as well as the environmental bacteria (Lelliottia, Butiauxella, and Kluyvera).

Contrasted Antibiotics and Pesticides Occurrence in Fish Exposed In Situ to Urban Effluents: A 20-Day Caging Experiment.

Urban freshwater ecosystems receive a wide array of organic pollutants through wastewater-treatment plant (WWTP) discharges and agricultural runoff. Evaluating the fate and effects of antibiotics and pesticides can be a challenging task, especially the effects on freshwater vertebrates because of their abilities to metabolize and excrete these chemicals and because of their high mobility and escape behavior when exposed to stressful environmental conditions. In the present study, 37 wild gudgeons (Gobio gobio) were caged for a period of up to 20 days, upstream and downstream of a WWTP effluent discharge in the Orge River (a tributary of the Seine River, France). Levels of pesticides and antibiotics in fish muscles were monitored weekly and compared with environmental contamination (water and sediments). Our results highlighted a slight bioaccumulation of pesticides in the gudgeon muscles at the downstream site after 20 days of exposure. Concerning antibiotics, ofloxacin was the most detected compound in fish muscles (85% of occurrence) and ranged from undetectable to 8 ng g-1 dry weight. Antibiotic levels in fish muscle were not higher at the downstream site and did not increase with exposure duration, despite high levels in the water (up to 29 times greater than upstream). Potential ecotoxicological effects were also evaluated: Body condition did not differ between the caging location and exposure time. Three oxidative status markers in the fish livers showed significant shifts after 14 days of caging. Our results suggest a high clearance rate of antibiotics and, to a lesser extent, of pesticides in wild gudgeons, which could be explained by changes in xenobiotic metabolism with pollutant exposure. Environ Toxicol Chem 2024;43:701-711. © 2023 SETAC.

Evidence of environmental transfer of tebuconazole to the eggs in the house sparrow (Passer domesticus): An experimental study.

Triazole compounds are among the most widely used fungicides in agroecosystems to protect crops from potential fungal diseases. Many farmland birds spend a significant part of their life cycle in agroecosystems, which may chronically expose them to pesticides. We experimentally tested whether exposure to environmental concentrations of tebuconazole could induce a contamination of the eggs in an agroecosystem sentinel species, the house sparrow (Passer domesticus). Wild-caught adult sparrows were maintained in captivity and exposed (exposed group) or not (control group) for seven months to tebuconazole through drinking water. Eggs were opportunistically collected for the determination of tebuconazole concentration by Liquid Chromatography coupled to tandem Mass Spectrometry in eggs. We found that eggs from exposed parents all contained tebuconazole with a mean concentration of 1.52 ng g-1 dry weight. In eggs from control parents, the tebuconazole concentration was below the limit of quantification (0.23 ng g-1 dry weight) for 11 out of 13 eggs. Thus, our study demonstrates for the first time that environmental exposure of female birds to tebuconazole can translate into egg contamination by this fungicide.

Narrower isotopic niche size in fish infected by the intestinal parasite Pomphorhynchus sp. compared to uninfected ones.

Examples of parasite-related effects on intermediate crustacean hosts are numerous but their ecological consequences on their vertebrate hosts are scarce. Here, we address the role of macroparasite infections on the trophic niche structure of definitive hosts and its potential physiological consequences using wild fish populations infected with an acantochephalan parasite Pomphorhynchus sp., a trophically transmitted intestinal worm. Infected and uninfected fish were sampled from six populations on the Marne River, France and the prevalence of intestinal parasites in the host populations ranged from 50% to 90%. Although the isotopic ratios (δ13 C and δ15 N) did not differ between infected and uninfected fish, we found a consistent pattern of isotopic niche size being considerably smaller in infected hosts when compared with noninfected ones. This was not explained by interindividual differences in intrinsic factors such as length/age or body condition between infected and uninfected fish. These results suggest a potential niche specialization of infected fish, which did not impair their energetic status.

Mercury contamination and potential health risks to Arctic seabirds and shorebirds.

Since the last Arctic Monitoring and Assessment Programme (AMAP) effort to review biological effects of mercury (Hg) on Arctic biota in 2011 and 2018, there has been a considerable number of new Arctic bird studies. This review article provides contemporary Hg exposure and potential health risk for 36 Arctic seabird and shorebird species, representing a larger portion of the Arctic than during previous AMAP assessments now also including parts of the Russian Arctic. To assess risk to birds, we used Hg toxicity benchmarks established for blood and converted to egg, liver, and feather tissues. Several Arctic seabird populations showed Hg concentrations that exceeded toxicity benchmarks, with 50 % of individual birds exceeding the "no adverse health effect" level. In particular, 5 % of all studied birds were considered to be at moderate or higher risk to Hg toxicity. However, most seabirds (95 %) were generally at lower risk to Hg toxicity. The highest Hg contamination was observed in seabirds breeding in the western Atlantic and Pacific Oceans. Most Arctic shorebirds exhibited low Hg concentrations, with approximately 45 % of individuals categorized at no risk, 2.5 % at high risk category, and no individual at severe risk. Although the majority Arctic-breeding seabirds and shorebirds appeared at lower risk to Hg toxicity, recent studies have reported deleterious effects of Hg on some pituitary hormones, genotoxicity, and reproductive performance. Adult survival appeared unaffected by Hg exposure, although long-term banding studies incorporating Hg are still limited. Although Hg contamination across the Arctic is considered low for most bird species, Hg in combination with other stressors, including other contaminants, diseases, parasites, and climate change, may still cause adverse effects. Future investigations on the global impact of Hg on Arctic birds should be conducted within a multi-stressor framework. This information helps to address Article 22 (Effectiveness Evaluation) of the Minamata Convention on Mercury as a global pollutant.

Dysbiosis of fish gut microbiota is associated with helminths parasitism rather than exposure to PAHs at environmentally relevant concentrations.

Although parasite infection and pollution are common threats facing wild populations, the response of the gut microbiota to the joint impact of these stressors remains largely understudied. Here, we experimentally investigated the effects of exposure to Polycyclic Aromatic Hydrocarbons (PAHs) and infection by a common acanthocephalan intestinal parasite (Pomphorhynchus sp.) on the gut microbial flora of a freshwater fish, the European chub (Squalius cephalus). Naturally infected or uninfected individuals were exposed to PAHs at environmentally realistic concentrations over a five-week period. Characterization of the gut bacterial community through 16S rRNA gene amplicon sequencing revealed that parasitic infection was a more structuring factor of bacterial diversity and composition than PAH exposure. Specifically, chub infected by Pomphorhynchus sp. harbored significantly less evenly represented gut bacterial communities than the uninfected ones. In addition, substantial changes in sequence abundance were observed within the main bacterial phyla, including the Firmicutes, Fusobacteriota, Actinobacteriota, and Proteobacteria. Again, these compositional changes correlated with host infection with Pomphorhynchus sp., confirming its pivotal role in gut microbial assemblage. Overall, these results highlight the importance of defining the parasitic status of individuals when conducting microbial ecotoxicological analyses at the digestive tract level, as this should lead to better understanding of microbiota modulations and help to identify microbial markers specifically associated with chemicals.

A U-Turn for Mercury Concentrations over 20 Years: How Do Environmental Conditions Affect Exposure in Arctic Seabirds?

Mercury (Hg) is highly toxic in its methylated form (MeHg), and global change is likely to modify its bioavailability in the environment. However, it is unclear how top predators will be impacted. We studied blood Hg concentrations of chick-rearing black-legged kittiwakes Rissa tridactyla (2000-2019) in Svalbard (Norway). From 2000 to 2019, Hg concentrations followed a U-shaped trend. The trophic level, inferred from nitrogen stable isotopes, and chlorophyll a (Chl a) concentrations better predicted Hg concentrations, with positive and U-shaped associations, respectively. As strong indicators of primary productivity, Chl a concentrations can influence production of upper trophic levels and, thus, fish community assemblage. In the early 2000s, the high Hg concentrations were likely related to a higher proportion of Arctic prey in kittiwake's diet. The gradual input of Atlantic prey in kittiwake diet could have resulted in a decrease in Hg concentrations until 2013. Then, a new shift in the prey community, added to the shrinking sea ice-associated release of MeHg in the ocean, could explain the increasing trend of Hg observed since 2014. The present monitoring provides critical insights about the exposure of a toxic contaminant in Arctic wildlife, and the reported increase since 2014 raises concern for Arctic seabirds.

Parasitism reduces oxidative stress of fish host experimentally exposed to PAHs.

Some parasites are known to bioaccumulate some environmental pollutants within their host. We hypothesized that these parasites may be beneficial for their hosts in polluted environments. We experimentally increased long-term (five weeks) exposure to polycyclic aromatic hydrocarbons (PAHs, three levels: 0.1X, 1X, 10X environmental exposure) in European chubs (Squalius cephalus) that were naturally infected or uninfected with acanthocephalan parasites. We monitored PAHs levels in fish tissues, as well as oxidative stress, telomere length and condition indices. Although parasite infection did not significantly reduce the levels of PAHs and PAH metabolites in host tissues, host oxidative status was explained by parasitism and pollution levels. Oxidative damage increased with parasitism in fish exposed to low PAH levels (0.1X) but decreased in infected fish at higher PAH exposure (10X), thus corroborating our hypothesis. Meanwhile, antioxidant capacity did not differ in response to parasite infection nor PAHs exposure. Despite this imbalance in oxidative status, experimental increase in PAH levels did not compromise telomere length, body condition, or survival in infected and uninfected fish. This study provides the first experimental evidence that the outcome of host-parasite interactions can shift from negative to positive as pollutant exposure increases.

Determinants of Legacy Persistent Organic Pollutant Levels in the European Pond Turtle (Emys orbicularis) in the Camargue Wetland, France.

Many banned persistent organic pollutants (POPs) remain for decades in the aquatic environment and can have harmful effects on long-lived predators because of their high bioaccumulation and biomagnification potentials. We investigated the occurrence and levels of 18 polychlorinated biphenyls (PCBs) and 16 organochlorine pesticides in European pond turtles (n = 174) from April to July 2018 in the Camargue wetland, France. Although the Camargue was highly contaminated in previous decades, plasma occurrence and levels of POPs were very low: we were able to quantify only 3 of the 34 compounds we analyzed in >10% of the turtles. The burdens from POPs did not differ between males and females and were uncorrelated with sampling date and body mass. We observed differences in POP burdens between turtles from the 2 sampling sites. One possible explanation is that the sampling sites were in different agricultural hydraulic systems: plasma occurrence and levels were higher for PCB-52 and hexachlorobenzene in turtles captured in drainage channels and for PCB-153 at the site that receives irrigation. Finally, the occurrence and levels of PCB-153 in turtles increased with age, likely because of bioaccumulation and much higher exposure 20 to 30 yr ago than now. Environ Toxicol Chem 2021;40:2261-2268. © 2021 SETAC.

Fish from urban rivers and with high pollutant levels have shorter telomeres.

Environmental pressures, such as urbanization and exposure to pollutants may jeopardize survival of free-living animals. Yet, much remains to be known about physiological and ecological responses to currently-released pollutants, especially in wild vertebrate ectotherms. We tested the effect of urbanization and pollution (phthalates, organochlorine and pyrethroid pesticides, polychlorobiphenyls, polybromodiphenylethers, polycyclic aromatic hydrocarbons, and some of their metabolites) on telomere length, a suggested biomarker of life expectancy, in the European chub, Squalius cephalus, from urban and agricultural rivers of the Marne hydrographic network, France. We showed that telomere length was reduced in chub from urban rivers. Moreover, among the wide range of anthropogenic contaminants investigated, high levels of phthalate metabolites in liver were associated with shorter telomeres. This study suggests that urbanization and chemical pollution may compromise survival of wild fish, by accelerating telomere attrition.

Urbanization Constrains Skin Bacterial Phylogenetic Diversity in Wild Fish Populations and Correlates with the Proliferation of Aeromonads.

Changes in the state of rivers resulting from the activity and expansion of urban areas are likely to affect aquatic populations by increasing stress and disease, with the microbiota playing a potentially important intermediary role. Unraveling the dynamics of microbial flora is therefore essential to better apprehend the impact of anthropogenic disturbances on the health of host populations and the ecological integrity of hydrosystems. In this context, the present study simultaneously examined changes in the microbial communities associated with mucosal skin and gut tissues of eight fish species along an urbanization gradient in the Orge River (France). 16S rRNA gene metabarcoding revealed that the structure and composition of the skin microbiota varied substantially along the disturbance gradient and to a lesser extent according to fish taxonomy. Sequences affiliated with the Gammaproteobacteria, in particular the genus Aeromonas, prevailed on fish caught in the most urbanized areas, whereas they were nearly absent upstream. This rise of opportunistic taxa was concomitant with a decline in phylogenetic diversity, suggesting more constraining environmental pressures. In comparison, fish gut microbiota varied much more moderately with the degree of urbanization, possibly because this niche might be less directly exposed to environmental stressors. Co-occurrence networks further identified pairs of associated bacterial taxa, co-existing more or less often than expected at random. Few correlations could be identified between skin and gut bacterial taxa, supporting the assumption that these two microbial niches are disconnected and do not suffer from the same vulnerability to anthropic pressures.

Effects of DEHP on the ecdysteroid pathway, sexual behavior and offspring of the moth Spodoptera littoralis.

Bis(2-ethylhexyl) phthalate (DEHP) is a widely produced plasticizer that is considered to act as an endocrine-disrupting chemical in vertebrates and invertebrates. Indeed, many studies have shown that DEHP alters hormonal levels, reproduction and behavior in vertebrates. Few studies have focused on the effects of DEHP on insects, although DEHP is found almost everywhere in their natural habitats, particularly in soils and plants. Here, we investigated the effects of DEHP on the sexual behavior and physiology of a pest insect, the noctuid moth Spodoptera littoralis. In this nocturnal species, olfaction is crucial for sexual behavior, and ecdysteroids at the antennal level have been shown to modulate sex pheromone detection by males. In the present study, larvae were fed food containing different DEHP concentrations, and DEHP concentrations were then measured in the adults (males and females). Hemolymphatic ecdysteroid concentrations, the antennal expression of genes involved in the ecdysteroid pathway (nuclear receptors EcR, USP, E75, and E78 and calmodulin) and sexual behavior were then investigated in adult males. The success and latency of mating as well as the hatching success were also studied in pairs consisting of one DEHP male and one uncontaminated female or one DEHP female and one uncontaminated male. We also studied the offspring produced from pairs involving contaminated females to test the transgenerational effect of DEHP. Our results showed the general downregulation of nuclear receptors and calmodulin gene expression associated with the higher concentrations of DEHP, suggesting peripheral olfactory disruption. We found some effects on male behavior but without an alteration of the mating rate. Effects on offspring mortality and developmental rates in the N + 1 generation were also found at the higher doses of DEHP. Taken together, the results of the study show for the first time that larval exposure to DEHP can induce delayed endocrine-disruptive effects in the adults of a terrestrial insect as well as effects on the next generation. To date, our study is also the first description of an impact of endocrine disrupter on olfaction in insects.

Trophic Transfer of Micropollutants and Their Metabolites in an Urban Riverine Food Web.

Trophic magnification factors (TMFs, i.e., the average change in the log-concentration of a pollutant per trophic level) have been extensively assessed for the so-called persistent organic pollutants, especially organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs), which are biomagnified along the food web. In contrast, trophic dilution was documented for pollutants with a high metabolic conversion rate, such as phthalate plasticizers and polycyclic aromatic hydrocarbons (PAHs). However, the fate of their metabolites across the food web has been rarely investigated. In this comparative study, the trophodynamics of 104 micropollutants and 25 of their metabolites were investigated in a freshwater food web from the urban Orge River, France. Trophic levels were determined using stable isotopes. Pyrethroid pesticides and their metabolites were not detected. As predicted, PCBs and OCPs biomagnified (TMF >1), while all chlorinated paraffins (CPs), PAHs, and phthalates underwent a trophic dilution (TMF <1). TMFs significantly decreased with a metabolic transformation rate and increased with hydrophobicity. The levels of PAH or phthalate metabolites were not significantly correlated with trophic levels or underwent a trophic dilution. This study highlighted that the relative contribution of metabolite levels in TMF values calculated for both parent compound and its metabolite(s) is weak compared to TMF values of the parent compound only in a riverine food web.

Monitoring freshwater fish communities in large rivers using environmental DNA metabarcoding and a long-term electrofishing survey.

Monitoring freshwater fish communities in a large human-impacted river is a challenging task. The structure of fish assemblages has been monitored yearly in the Marne and the Seine Rivers, across the Paris conurbation, France, using traditional electrofishing (EF) surveys since 1990, in accordance with the European Water Framework Directive. In addition, metabarcoding of DNA extracted from environmental samples (eDNA) was concomitantly conducted in nine sampling sites in 2017 and in 2018 to compare the estimates of species richness and relative abundance among three methods: annual, long-term EF monitoring and eDNA. The present study confirms better detection of fish species using eDNA compared to annual EF. eDNA metabarcoding was also more efficient for species detection than a 3-6-year EF survey but was similar or less efficient than a long-term EF survey of 14 years of monitoring. In addition, the numbers of reads per species relative to the total number of reads significantly increased with (a) increasing relative abundance (relative percentage of individuals caught per species) and (b) increasing number of years that a fish species was detected during the 2000-2018 period. These results suggest that eDNA could reflect local population persistence.

Potential Benefits of Acanthocephalan Parasites for Chub Hosts in Polluted Environments.

Some parasites are expected to have beneficial impacts on wild populations in polluted environments because of their bioaccumulation potential of pollutants from their hosts. The fate of organic micropollutants in host-parasite systems and the combined effect of parasitism and pollution were investigated in chub Squalius cephalus, a freshwater fish, infected (n = 73) or uninfected (n = 45) by acanthocephalan parasites Pomphorhynchus sp. from differently contaminated riverine sites. Several ubiquitous pollutants (polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated diphenyl-ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), phthalates, insecticides, pyrethroids, and N,N-diethyl-meta-toluamide (DEET)) and some of their metabolites were characterized for the first time in parasites and various fish matrices (muscle, liver, and stomach content). Most organic pollutants reached higher levels in parasites than in chub matrices. In contrast, metabolite levels were lower in parasite tissues compared to fish matrices. Infected and uninfected chub exhibited no significant differences in their pollutant load. Body condition, organo-somatic indices, and immunity were not affected by parasitism, and few correlations were found with chemical pollution. Interestingly, infected chub exhibited lower oxidative damage compared to uninfected fish, irrespective of their pollutant load. In light of these results, this correlative study supports the hypothesis that acanthocephalan parasites could bring benefits to their hosts to cope with organic pollution.

Biomagnification of perfluoroalkyl acids (PFAAs) in the food web of an urban river: assessment of the trophic transfer of targeted and unknown precursors and implications.

The present work examined the trophic transfer of perfluoroalkyl and polyfluoroalkyl substances (PFASs) in a typical urban river (Orge River, near Paris, France), and aimed to investigate the potential contribution of precursors to the biomagnification of perfluoroalkyl acids (PFAAs). Sixteen PFAAs, twelve of their precursors (pre-PFAAstargeted) and two fluorinated alternatives to long-chain PFASs were analyzed in water, sediments and biota (including biofilm, invertebrates and fish). Twenty two compounds were detected in biological samples (2.0-147 ng g-1 wet weight), perfluorooctane sulfonate (PFOS) and C12-C14 perfluoroalkyl carboxylates (PFCAs) being predominant while ∑pre-PFAAstargeted contributed to 1-18% of ∑PFASs. Trophic magnification factors (TMFs) were >1 (i.e. denoting biomagnification) for C9-C14 PFCAs, C7-C10 perfluoroalkyl sulfonates (PFSAs) and several pre-PFAAs (e.g. 8 : 2 and 10 : 2 fluorotelomer sulfonates). The significant decrease in ∑pre-PFCAs/∑PFCAs concentration ratio with trophic level suggested a likely contribution of selected precursors to the biomagnification of PFCAs through biotransformation, while this was less obvious for PFOS. The total oxidizable precursor assay, applied for the first time to sediment and biota, revealed the presence of substantial proportions of extractable unknown pre-PFAAs in all samples (i.e. 15-80% of ∑PFASs upon oxidation). This proportion significantly decreased from sediments to invertebrates and fish, thereby pointing to the biotransformation of unattributed pre-PFAAs in the trophic web, which likely contributes to the biomagnification of some PFAAs (i.e. C9-C12 PFCAs and C7-C10 PFSAs).

Multiresidue Methods for the Determination of Organic Micropollutants and Their Metabolites in Fish Matrices.

Two analytical methods were developed for the determination of 48 organic compounds and 20 of their main by-products in fish matrices. The targeted compounds belong to various chemical classes of metabolizable (phthalates, polycyclic aromatic hydrocarbons, insecticides [pyrethroids and N,N-diethyl-meta-toluamide]) and legacy (organochlorine pesticides, polychlorinated biphenyls, polybrominated diphenyl ethers) pollutants. Analyses were performed by gas and liquid chromatography-tandem mass spectrometry in multiple reaction monitoring (MRM) and dynamic MRM, respectively. Method performances were satisfactory, with results meeting the validation criteria because they achieved good linearity responses, recovery, precision, and accuracy for most of the 68 investigated compounds. The methods were then applied on 3 feral chub (Squalius cephalus) collected from the Marne hydrographic network (France). Twenty-six parent compounds and 5 metabolites were systematically detected in fish matrices, with substantial concentration variability within and among individuals. Phthalates and pyrethroids accounted for most of the pollutant load. Metabolite concentrations in liver samples exceeded those of parent molecules in fish muscle. The present study presents 2 reliable methods for the determination of a wide range of contaminants and underlines the importance of metabolite analysis for a more comprehensive understanding of pollutant bioaccumulation and fate in aquatic organisms. Environ Toxicol Chem 2019;38:1866-1878. © 2019 SETAC.

Effects of DEHP on post-embryonic development, nuclear receptor expression, metabolite and ecdysteroid concentrations of the moth Spodoptera littoralis.

Di (2-ethylhexyl) phthalate (DEHP) is recognized in vertebrates as an Endocrine Disrupting Chemical (EDC). DEHP can alter steroid hormones production, development, reproduction and behavior in vertebrates. Only few studies investigated DEHP effects on insects. However, some recent studies on aquatic insects showed that DEHP could also act as an EDC by interfering with the signaling pathways of ecdysteroids, the main hormones involved in the control of insect post-embryonic development and physiology. The aim of the study was to investigate (1) the fate of DEHP within a terrestrial insect species by exposing larvae to food containing a wide range of DEHP concentrations and (2) the effects of this chemical on their post-embryonic development and metamorphosis, by using a multi-level approach. DEHP was shown to be present both in larvae and resulting stages, with higher concentrations in chrysalises and adults than in larvae. DEHP concentrations also decreased at the end of the last larval instar, suggesting the metabolic transformation or excretion of this chemical during this time. Only the two highest DEHP doses induced higher insect mortality, whereas low and intermediate concentrations increased larval food consumption without affecting body weight. Metabolic profiles showed that in control insects, the last three days before metamorphosis correspond to a metabolic transition, but with time-dependent changes in treated insects. Interestingly, DEHP treatments also alter both hemolymphatic ecdysteroid titers and expression levels of ecdysteroid response genes. These results confirm that DEHP can alter insect post-embryonic development and metamorphosis, by interfering with ecdysteroid pathways.