Toxicity of glyphosate-based pesticides to four North American frog species

FRET-based Solid-state Luminescent Glyphosate Sensor Using Calixarene-grafted Ruthenium(II)bipyridine Doped Silica Nanoparticles

Calixarene-functionalized luminescent nanoparticles were successfully fabricated for the FRET-based selective and sensitive detection of the organophosphorus pesticide glyphosate (GP). p-Tert-butylcalix[4]arene was grafted on the surface of [Ru(bpy)₃ ]²⁺ incorporated SiNps to produce self-assembled nanosensors (RSC). FRET was switched on in the presence of GP by means of energy transfer due to binding with p-tert-butylcalix[4]arene grafted on the surface of the RSC. The FRET efficiency of the GP-RSC system was increased gradually with the addition of GP. The FRET efficiency was evaluated as 87.69 % and a high binding affinity was established by the binding constant value, 1.16×10⁷  M^-1 , using a Langmuir binding isotherm plot. The estimated limit of detection (LOD) was 7.91×10^-7  M, which was lower than the Environmental Protection Agency (EPA) recommendation. The probe also effectively responds to real sample analysis. The sensitivity and selectivity was realized due to the efficient FRET towards the fluorescence properties of the [Ru(bpy)₃ ]²⁺ complex.

Effects of glyphosate and its commercial formulation, Roundup® Ultramax, on liver histology of tadpoles of the neotropical frog, Leptodactylus latrans (amphibia: Anura)

In the last years, the agricultural expansion has led to an increased use of pesticides, with glyphosate as the most widely used worldwide. This is also the situation in Argentina, where glyphosate formulations are the most commercialized herbicides. It is known that glyphosate formulations are much more toxic than the active ingredient, and this difference in toxicity can be attributed to the adjuvants present in the formula. In this context, the aim of the present study was to evaluate and compare sub-lethal histological effects of the glyphosate formulation Roundup Ultramax and glyphosate active ingredient on Leptodactylus latrans tadpoles at Gosner-stage 36. Semi-static bioassays were performed using 96 h of exposure with Roundup Ultramax formulation (RU; 0.37-5.25 mg a.e./L), glyphosate (GLY; 3-300 mg/L), and a control group. RU exposure showed an increment in the melanomacrophagic cells (MMc) and melanomacrophagic centers (MMCs) from 0.37 mg a.e./L. GLY exposure showed a significant increment in the number of MMc from 15 mg/L, and of MMCs from 3 mg/L. Also, histopathological lesions were observed in the liver of tadpoles exposed to both, GLY and RU. These lesions included: lipidosis and hepatic congestion, but only RU showed significant differences respect to control, with a LOEC value of 2.22 mg a.e./L for both effects. In sum, this study represents the first evidence of adverse effects of glyphosate and RU formulation on the liver of anuran larvae at concentrations frequently found in the environment.

Comparative Assessment on Mechanism Underlying Renal Toxicity of Commercial Formulation of Roundup Herbicide and Glyphosate Alone in Male Albino Rat

There have been major concerns that the nephrotoxicity of commercial formulations of Roundup herbicide is due to the active ingredient glyphosate. We therefore investigated and compared the mechanisms underlining the nephrotoxicity of Roundup herbicide and glyphosate alone in rat. Fifty-six adult male rats randomized into 7 groups of 8 rats per group were exposed to Roundup formulation and glyphosate alone daily by gavage at 3.6, 50.4, and 248.4 mg/kg body weight (bw) of glyphosate concentrations for 12 weeks with distilled water administered to the control group. Kidney biomarker (serum urea and creatinine, plasma cystatin-C, and neutrophil gelatinase-associated lipocalin), oxidative stress indices in the kidney tissue, activities of kidney membrane-bound enzymes (Mg-adenosine triphosphatase [ATPase], Ca-ATPase, Na/K-ATPase, and total ATPase), and histopathological changes in the kidney were monitored. Glyphosate concentration in the kidney was quantified by high-performance liquid chromatography with ultraviolet detection. Significant ( P < 0.05) alterations in the levels of the kidney biomarker, oxidative stress markers, and membrane-bound enzymes were observed in the rats exposed to Roundup compared to the rats exposed to glyphosate alone. Rats exposed to Roundup accumulated more glyphosate residue in their kidney tissue. Severe histopathological lesions were only seen in the kidneys of rats exposed to Roundup. The nephrotoxicity observed cannot be due to the active ingredient in the Roundup formulation, as glyphosate alone has virtually no effect on the renal function of the exposed animals. Therefore, the general claim attributing nephrotoxicity of a glyphosate-based herbicide to its active ingredient should be discouraged.

Effects of glyphosate on the non-target leaf beetle Cerotoma arcuata (Coleoptera: Chrysomelidae) in field and laboratory conditions

This study aimed to assess the glyphosate application effects on the Cerotoma arcuata Oliver (Coleoptera: Chrysomelidae) population in glyphosate-resistant soybean crops. Field studies were conducted with glyphosate and the insecticide endosulfan to observe the effects of these pesticides on C. arcuata, on its damages in the crop and on the populations of natural enemies in glyphosate-resistant soybean crops. Moreover, the lethal and behavioral sublethal response of C. arcuata to glyphosate and endosulfan was conducted in the laboratory. The results of the field and laboratory experiments showed that glyphosate caused moderate toxicity and high irritability in C. arcuata and that endosulfan caused high toxicity and irritability. Therefore, the direct effect of glyphosate on C. arcuata was negative and does not explain the population increases of this pest in glyphosate-resistant soybean. However, the glyphosate also decreased the density of predators. Thus, the negative effect of glyphosate on the predators may be related to population increases of C. arcuata in glyphosate-resistant soybean crops, however, more studies are needed to better evidence this relationship. This study suggests that glyphosate can impact other non-target organisms, such as herbivorous insects and natural enemies and that the use of this herbicide will need to be carefully stewarded to prevent potential disturbances in beneficial insect communities in agricultural systems.

Simulated developmental and reproductive impacts on amphibian populations and implications for assessing long-term effects

Fish endpoints measured in early life stage toxicity tests are often used as representative of larval amphibian sensitivity in Ecological Risk Assessment (ERA). This application potentially overlooks the impact of developmental delays on amphibian metamorphosis, and thereby reduced survival, in amphibian populations constrained by habitat availability. Likewise, the effects of reduced productivity or altered sexual development as a result of chemical exposure are not presented in terms of lower population fecundity in these surrogate tests. Translating endpoints measured in toxicity tests to those that are more representative of amphibian ecology and population dynamics provides a means of identifying how developmental effects result in long-term impacts. Here we compare effects of developmental delay on metamorphosis success in six anuran species and simulate population-level impacts of subsequent reductions in larval survival as well as potential reductions in fecundity as a result of developmental impacts. We use deterministic matrix models to compare realistic combinations of amphibian demographic rates and relative impacts of reduced growth on larval survival and subsequently on population growth. Developmental delays are less detrimental in species with longer and less synchronous larval periods. All six species were most sensitive to changes in first-year survival, and damping ratios were generally a good indicator of resilience to perturbations in both larval survival and fecundity. Further identification of species and population-level vulnerabilities can improve the evaluation of sublethal effects in relevant context for ERA.

A glyphosate micro-emulsion formulation displays teratogenicity in Xenopus laevis

Glyphosate is the active ingredient in broad-spectrum herbicide formulations used in agriculture, domestic area and aquatic weed control worldwide. Its market is growing steadily concurrently with the cultivation of glyphosate-tolerant transgenic crops and emergence of weeds less sensitive to glyphosate. Ephemeral and lentic waters near to agricultural lands, representing favorite habitats for amphibian reproduction and early life-stage development, may thus be contaminated by glyphosate based herbicides (GBHs) residues. Previous studies on larval anuran species highlighted increased mortality and growth effects after exposure to different GBHs in comparison to glyphosate itself, mainly because of the surfactants such as polyethoxylated tallow amine present in the formulations. Nevertheless, these conclusions are not completely fulfilled when the early development, characterized by primary organogenesis events, is considered. In this study, we compare the embryotoxicity of Roundup® Power 2.0, a new GBH formulation currently authorized in Italy, with that of technical grade glyphosate using the Frog Embryo Teratogenesis Assay-Xenopus (FETAX). Our results evidenced that glyphosate was not embryolethal and only at the highest concentration (50 mg a.e./L) caused edemas. Conversely, Roundup® Power 2.0 exhibited a 96 h LC50 of 24.78 mg a.e./L and a 96 h EC50 of 7.8 mg a.e./L. A Teratogenic Index of 3.4 was derived, pointing out the high teratogenic potential of the Roundup® Power 2.0. Specific concentration-dependent abnormal phenotypes, such as craniofacial alterations, microphthalmia, narrow eyes and forebrain regionalization defects were evidenced by gross malformation screening and histopathological analysis. These phenotypes are coherent with those evidenced in Xenopus laevis embryos injected with glyphosate, allowing us to hypothesize that the teratogenicity observed for Roundup® Power 2.0 may be related to the improved efficacy in delivering glyphosate to cells, guaranteed by the specific surfactant formulation. In conclusion, the differences in GBH formulations should be carefully considered by the authorities, since sub-lethal and/or long-term effects (e.g. teratogenicity) can be significantly modulated by the active ingredient salt type and concentration of the adjuvants. Finally, the mechanistic toxicity of glyphosate and GBHs are worthy of further research.

Glyphosate, a chelating agent-relevant for ecological risk assessment?

Glyphosate-based herbicides (GBHs), consisting of glyphosate and formulants, are the most frequently applied herbicides worldwide. The declared active ingredient glyphosate does not only inhibit the EPSPS but is also a chelating agent that binds macro- and micronutrients, essential for many plant processes and pathogen resistance. GBH treatment may thus impede uptake and availability of macro- and micronutrients in plants. The present study investigated whether this characteristic of glyphosate could contribute to adverse effects of GBH application in the environment and to human health. According to the results, it has not been fully elucidated whether the chelating activity of glyphosate contributes to the toxic effects on plants and potentially on plant-microorganism interactions, e.g., nitrogen fixation of leguminous plants. It is also still open whether the chelating property of glyphosate is involved in the toxic effects on organisms other than plants, described in many papers. By changing the availability of essential as well as toxic metals that are bound to soil particles, the herbicide might also impact soil life, although the occurrence of natural chelators with considerably higher chelating potentials makes an additional impact of glyphosate for most metals less likely. Further research should elucidate the role of glyphosate (and GBH) as a chelator, in particular, as this is a non-specific property potentially affecting many organisms and processes. In the process of reevaluation of glyphosate its chelating activity has hardly been discussed.

Ovarian growth impairment after chronic exposure to Roundup Ultramax® in the estuarine crab Neohelice granulata

Adult females of the estuarine crab Neohelice granulata were exposed to the glyphosate formulation Roundup Ultramax® during the entire 3-month pre-reproductive period. At the end of the assay, a significant higher increment of glycemia was noted at both glyphosate concentrations assayed (0.01 and 0.2 mg/L, acid equivalent). Although no differences were observed in the gonadosomatic index, a significantly higher proportion of reabsorbed vitellogenic oocyte was observed at the highest glyphosate concentration, together with a significant decrease of vitellogenin content in the ovary. In addition, some in vitro assays were carried out by co-incubating small pieces of ovary with or without the addition of Roundup; at both concentrations tested (same as those used in vivo), a decrease in the ovarian vitellogenin content was observed, whereas the ovarian protein synthesis was significantly inhibited by glyphosate at 0.2 mg/L in the Roundup formulation used.

Oxidative stress induced by glyphosate-based herbicide on freshwater turtles

Freshwater ecosystems face very strong anthropogenic pressures, among which overexploitation, habitat degradation, flow modification, species invasion, and water pollution lead to growing threats on biodiversity. Urbanization through wastewater treatment, industry through the release of inorganic and organic chemicals, and agriculture through the use of pesticides and herbicides are the main factors involved in water pollution. In France, more precisely in the Pyrénées-Orientales department, the poor quality of the watercourses is attributable overall to the use of glyphosate-based herbicides in agricultural activities. Because these chemicals can impact individuals, populations, and biodiversity, we investigated, under experimental conditions, the physiological response of animals facing abiotic contaminants. We selected as a model, juveniles of the freshwater turtle Trachemys scripta elegans. We measured the gene expression and activity of the catalase and superoxide dismutase enzymes as well as the levels of lipid peroxidation, which are all oxidative stress biomarkers, in turtles challenged with high concentrations of glyphosate-based herbicides, on the one hand, and with degraded waters collected from a local watercourse, on the other. We also measured the acetylcholinesterase activity across the same animals. We showed through variations in gene expression and enzyme activity that a glyphosate commercial formulation induced a stress in turtles. A similar outcome was obtained when turtles faced degraded waters. The results indicated that the poor quality of regional waters could be a real threat for animal health. Because turtles are globally less sensitive to contaminants than amphibians, which are lacking in the degraded waters of the Pyrénées-Orientales department, they could constitute an excellent model to follow the evolution of water quality through the study of oxidative stress biomarkers. Environ Toxicol Chem 2017;36:3343-3350. © 2017 SETAC.

In vitro assessment of skin sensitization, photosensitization and phototoxicity potential of commercial glyphosate-containing formulations

This study evaluated the applicability of a modified Direct Peptide Reactivity Assay (DPRA) (OECD N° 442C, 2015) through the 10-fold reduction of reaction volume (micro-DPRA, mDPRA) for skin sensitization evaluation of six commercial glyphosate-containing formulations. In addition, another modification of DPRA was proposed by adding a UVA (5J/cm2) irradiation step, namely photo-mDPRA, to better characterize (photo)sensitizer materials. The phototoxicity profile of pesticides was also evaluated using the 3T3 Neutral Red Uptake Phototoxicity Test (3T3-NRU-PT) (OECD N° 432, 2004). The mDPRA could represent an environmentally acceptable test approach, since it reduces costs and organic waste. Peptide depletion was greater in photo-mDPRA and changed the reactivity class of each test material, in comparison to mDPRA. Thus, the association of mDPRA with photo-mDPRA was better for correctly characterizing human (photo)sensitizer substances and pesticides. In general, cysteine depletion was greater than that of lysine for all materials tested in both mDPRA and photo-mDPRA. Furthermore, while 3T3-NRU-PT is unable to predict (photo)sensitizers, it was capable of correctly identifying the phototoxic potential of the tested agrochemical formulations. In conclusion, mDPRA plus photo-mDPRA and 3T3-NRU-PT seem to be preliminary non-animal test batteries for skin (photo)sensitization/phototoxicity assessment of chemicals, agrochemical formulations and their ingredients.

Stronger effects of Roundup than its active ingredient glyphosate in damselfly larvae

Pesticides are causing strong decreases in aquatic biodiversity at concentrations assumed safe by legislation. One reason for the failing risk assessment may be strong differences in the toxicity of the active ingredient of pesticides and their commercial formulations. Sublethal effects, especially those on behaviour, have been largely ignored in this context, yet can be equally important as lethal effects at the population and ecosystem levels. Here, we compared the toxicity of the herbicide Roundup and its active ingredient glyphosate on survival, but also on ecologically relevant sublethal traits (life history, behaviour and physiology) in damselfly larvae. Roundup was more toxic than glyphosate with negative effects on survival, behaviour and most of the physiological traits being present at lower concentrations (food intake, escape swimming speed) or even only present (survival, sugar and total energy content and muscle mass) following Roundup exposure. This confirms the toxicity of the surfactant POEA. Notably, also glyphosate was not harmless: a realistic concentration of 2mg/l resulted in reduced growth rate, escape swimming speed and fat content. Our results therefore indicate that the toxicity of Roundup cannot be fully attributed to its surfactant, thereby suggesting that also the new generation of glyphosate-based herbicides with other mixtures of surfactants likely will have adverse effects on non-target aquatic organisms. Ecotoxicological studies comparing the toxicity of active ingredients and their commercial formulations typically ignore behaviour while the here observed differential effects on behaviour likely will negatively impact damselfly populations. Our data highlight that risk assessment of pesticides ignoring sublethal effects may contribute to the negative effects of pesticides on aquatic biodiversity.

Influence of a Roundup formulation on glyphosate effects on steroidogenesis and proliferation of bovine granulosa cells in vitro

Glyphosate (N-phosphonomethyl-glycine) is a non-selective systemic herbicide widely used worldwide. The purpose of this study is to determine if glyphosate alone (GLPH) or in formulation with Roundup (G-RU) can affect granulosa cell proliferation and steroid production. Four experiments were conducted. In Exp. 1, 10 and 300 μg/mL of GLPH had no effect (P > 0.05) on cell numbers, estradiol or progesterone production, whereas 10 and 300 μg/mL of G-RU dramatically decreased (P < 0.05) cell numbers and estradiol and progesterone production. In Exp. 2, G-RU at 0.1 μg/mL had no significant effect whereas G-RU at 10 μg/mL decreased (P < 0.05) GC numbers, progesterone and estradiol production. In the absence of IGF1 but presence of FSH, 1 μg/mL of G-RU decreased (P < 0.05) estradiol production, whereas in the presence of IGF1 and FSH, 1 μg/mL of G-RU increased (P < 0.05) cell numbers, progesterone and estradiol production. In Exp. 3, IGF1 significantly increased cell numbers (by 2.8-fold) and estradiol (by 17.8-fold) and progesterone (by 6.1-fold) production. GLPH at 10 μg/mL alone had no significant effect on FSH-induced (i.e., basal) or FSH plus IGF1-induced cell numbers, estradiol or progesterone production. However, G-RU at 10 μg/mL significantly inhibited FSH plus IGF1-induced cell numbers, estradiol and progesterone production by 65%-91%. In Exp. 4, 48 h treatment of G-RU had no significant effect on viability of attached cells. In conclusion, the present studies demonstrate that GLPH and particularly G-RU may have the potential to impair reproductive function in cattle.

Standardize or Diversify Experimental Conditions in Ecotoxicology? A Case Study on Herbicide Toxicity to Larvae of Two Anuran Amphibians

Despite a steeply increasing number of ecotoxicological studies on the effects of pesticides on nontarget organisms, studies assessing the adequacy and reliability of different experimental approaches have remained scarce. We scrutinized effects of a glyphosate-based herbicide on larvae of two European anuran amphibians by estimating species-specific LC50 values, assessing how an additional stress factor may influence outcomes, and investigating whether replicate experiments yielded qualitatively the same results. We exposed Rana dalmatina and Bufo bufo tadpoles to two predator treatments (no predator vs. predator chemical cues) combined with varying herbicide concentrations, repeated the experiment with a subset of the experimental treatments and partly with slight modifications 1 week later and assessed survival. Our results indicated that the herbicide was moderately toxic to tadpoles. The presence of predator chemical cues did not affect the lethality of the herbicide in either species. The estimated sensitivity of R. dalmatina tadpoles varied considerably across experiments, whereas in case of B. bufo LC50 values remained very similar. Our results suggest that differences in the experimental setup may often have no influence on the measured effects of pesticides, whereas replicated experiments can deliver widely differing results in other cases, perhaps depending on the studied species, the population origin of the tested individuals, or the test conditions. This draws attention to the suggestion that strict standardization may not deliver widely applicable insights into the toxicity of contaminants and, instead, intentionally introducing variation into the design of ecotoxicological experiments and replicating entire experiments may prove highly beneficial.

Global research production in glyphosate intoxication from 1978 to 2015: A bibliometric analysis

BACKGROUND

Glyphosate (N-phosphonomethylglycine) has been used as a broad-spectrum herbicide that has been widely used in the agricultural industry and also available for home use. The main aim of this study is to present a general overview of glyphosate intoxication-related publications from its introducing since the early 1970s using bibliometric technique.

METHODS

On June 23, 2016, a literature search of the Scopus database was performed. We then extracted and analyzed the data using well-established qualitative and quantitative bibliometric indices: Publication year, affiliation, document type, country name, subject category, journal name, publishing language, and collaboration and citation patterns.

RESULTS

We recognized a total of 3735 publications on glyphosate published between 1973 and 2015. There were 875 publications related to glyphosate intoxication in the Scopus database published between 1978 and 2015. Articles (757) comprised 86.5% of the total publications, followed by reviews (41; 4.7%). Most publications were published in English (87.9%), followed by Portuguese (6.6%). The number of publications related to glyphosate intoxication increased from 44 in 1978-1987 up to 152 in 1996-2005 and then quadrupled in 2006-2015. The United States was the leading country with 180 documents representing 20.6%, followed by Brazil (120; 13.7%), Canada (78; 8.9%), Argentina (61; 7.0%), and France (57; 6.5%). The 85.6% of the publications was cited, and the average of citation per document was 17.13 with h-index of 55. Furthermore, the United States achieved the highest h-index of 33. Most of the global international collaborations are made with researchers from the United States, who collaborated with 23 countries/territories in 44 publications.

CONCLUSIONS

The trends in global glyphosate-related research between 1978 and 2015 were evaluated by a bibliometric technique. Results showed that English was the leading publishing language, and the major publication type was original article. Findings showed that number of research publications related to glyphosate intoxication increased significantly in the last decade. The United States and Brazil are the two most productive countries in research on glyphosate intoxication. This study will be beneficial to policy makers by identifying areas that need greater investment and research funding to target appropriate agriculture sectors so as to improve glyphosate safety in a global setting.

Effects of a glyphosate-based herbicide in pejerrey Odontesthes humensis embryonic development

Glyphosate-based herbicides (GBH) are the major pesticides used worldwide. Among them, the Roundup formulations are the most popular. Some aspects of GBH toxicity are well known, such as induction of oxidative stress. However, embryotoxicity is scarcely known. Therefore, the aim of the present study was to evaluate the effect of exposure to different Roundup Transorb R concentrations (0.36, 1.80, 3.62 and 5.43 mg glyphosate a.e./L) on Odontesthes humensis embryonic development. Embryos were sampled at three exposure times (48, 72 and 96 h). After 48 h, the stage of embryonic development and the number of somite pairs were analyzed; after 72 h, the percentage of pigmented embryos were evaluated and after 96 h, the eye diameter (ED) and the distance between eyes (DE) were measured. Mortality rates were daily calculated. Results show that Roundup exposure to all concentrations did not alter the endpoints evaluated at 48 and 72 h. On the other hand, exposure for 96 h to all concentrations induced a concentration-dependent reduction in ED and DE. Additionally, exposure to 5.43 mg a.e./L increased mortality. These findings indicate that Roundup has the potential to produce morphological alterations in fish embryos even at the lower and ecologically relevant concentration tested (0.36 mg a.e./L). This result corroborates the hypothesis that glyphosate alters the retinoic acid signaling pathway. Additionally, our findings indicate that exposure to high concentrations of Roundup (5.43 mg a.e./L) for 96 h causes high mortality rates of fish embryos. This is the first report of GBH embryotoxicity in an endemic fish of southern areas in South America.

Oxidative stress biomarkers in the Mediterranean pond turtle (Mauremys leprosa) reveal contrasted aquatic environments in Southern France

Increasing anthropogenic activities, like agricultural practices, constitute the main causes of the loss of water quality and disruption of freshwater ecosystems. High concentrations of pesticides, as shown under experimental conditions, can indeed impact freshwater animals. In Southern France, especially in the Pyrénées-Orientales department, because agricultural activities are mainly based on fruit crops and vineyards, glyphosate and AMPA were detected in some watercourses. Thereby we investigated the effects of degraded waters on the physiology of the endemic endangered freshwater species, namely the Mediterranean pond turtle Mauremys leprosa, in contrasted environments along the same rivers on the one hand and between different rivers on the other. We measured the activity and gene expression of two enzymes involved in the oxidative detoxification processes, namely the Catalase and the Superoxide dismutase. We showed significant variations in the Catalase gene expression and activity within turtles of the Fosseille River depending of their location, i.e. upstream or downstream of the wastewater treatment plants (WTP). Because agricultural environments are similar all along this river, they can no be longer considered as the unique source of turtle stress. The processed waters discharged by the WTP, which contribute to watercourses degradation, could therefore considerably impact the biodiversity of the freshwater environments.

Behaviour of glyphosate in a reservoir and the surrounding agricultural soils

Glyphosate (GPS) is an herbicide currently used on olive crops in Spain, and can be transported to the nearby reservoirs currently used for human consumption. The purpose of this work was to study the behaviour and environmental fate of GPS in water and sediments of the Vibora Reservoir, its tributary river, and the surrounding agricultural soils to assess the risk of water pollution of this reservoir. The adsorption of GPS by different matrices was as follows: heading of the reservoir sediment (Cabecera)>tail sediment (Cola)>soils>Vibora sediment. The highest amount of oxides (especially Fe oxides) was observed in sediments from Cabecera and Cola whereas the lowest values were recorded on Vibora sediment. Results indicate that the highest GPS adsorption is due to the amorphous oxides and the edge sites of the clay minerals. Glyphosate adsorption increased with decreasing pH from 8 to 7. The desorption percentage of GPS from the four soils studied ranged only from 0.40 to 1.22%. Desorption was almost irreversible for Cabecera and Cola sediments, with values between 0 and 1.1%. Conversely, Vibora sediment presented about 20% desorption, probably due to its coarse texture and lower levels of amorphous oxides. Hockey-stick first-order kinetics was the best descriptor for water glyphosate dissipation at the Cabecera and Cola locations, and simple first-order kinetic for the water from the tributary Vibora River. The half-lives (DT50) were between 6.3 and 11.0days. The rapid degradation of GPS in surface waters and its practically irreversible sorption on these soils and sediments implies that GPS use in similar agricultural areas is of very low environmental risk. This manuscript also outlines the importance of the presence of photo-sensitizers in waters in the degradation routes of GPS in reservoirs.

Chronic exposure to a glyphosate-based herbicide makes toad larvae more toxic

Chemical pollutants can exert various sublethal effects on wildlife, leading to complex fitness consequences. Many animals use defensive chemicals as protection from predators and diseases, yet the effects of chemical contaminants on this important fitness component are poorly known. Understanding such effects is especially relevant for amphibians, the globally most threatened group of vertebrates, because they are particularly vulnerable to chemical pollution. We conducted two experiments to investigate how exposure to glyphosate-based herbicides, the most widespread agrochemicals worldwide, affects the production of bufadienolides, the main compounds of chemical defence in common toads (Bufo bufo). In both experiments, herbicide exposure increased the amount of bufadienolides in toad tadpoles. In the laboratory, individuals exposed to 4 mg a.e./L glyphosate throughout their larval development had higher bufadienolide content at metamorphosis than non-exposed tadpoles, whereas exposure for 9 days to the same concentration or to 2 mg a.e./L throughout larval development or for 9 days had no detectable effect. In outdoor mesocosms, tadpoles from 16 populations exhibited elevated bufadienolide content after three-weeks exposure to both concentrations of the herbicide. These results show that pesticide exposure can have unexpected effects on non-target organisms, with potential consequences for the conservation management of toxin-producing species and their predators.

A full life-cycle bioassay with Cantareus aspersus shows reproductive effects of a glyphosate-based herbicide suggesting potential endocrine disruption

A full life-cycle (240 days) bioassay using the terrestrial snail, Cantareus aspersus, allowing exposure during embryogenesis and/or the growth and reproduction phases, was used to assess the effects of Bypass®, a glyphosate-based herbicide (GlyBH), on a range of endpoints, including parameters under endocrine control. As a positive control, a mixture (R-A) made of diquat (Reglone®) and nonylphenols (NP, Agral®), known for its endocrine disrupting effects in other organisms, was tested. At environmental concentrations, both pesticides (R-A mixture and GlyBH) enhanced growth but reduced reproduction. The R-A mixture acted mainly on the fecundity through a delay in egg-laying of approximately 20 days and a strongly reduced number of clutches. This latter dysfunction may be caused by a permanent eversion of the penis, suggesting a disrupting effect at the neuro-endocrine level, which prevented normal mating. GlyBH acted on fertility, possibly due to a decrease in the fertilization of eggs laid by adults exposed during their embryonic development. These results, associated with the absence of observed effects on gonad histology of GlyBH exposed snails, suggested that the underlying mechanisms are neuro-endocrine.

A review of ecological risk assessment methods for amphibians: Comparative assessment of testing methodologies and available data

Historically, ecological risk assessments have rarely included amphibian species, focusing preferentially on other aquatic (fish, invertebrates, algae) and terrestrial wildlife (birds and mammal) species. Often this lack of consideration is due to a paucity of toxicity data, significant variation in study design, uncertainty with regard to exposure, or a combination of all three. Productive risk assessments for amphibians are particularly challenging, given variations in complex life history strategies. Further consideration is needed for the development of useful laboratory animal models and appropriate experimental test procedures that can be effectively applied to the examination of biological response patterns. Using these standardized techniques, risk estimates can be more accurately defined to ensure adequate protection of amphibians from a variety of stress agents. Patterns in toxicity may help to ascertain whether test results from 1 amphibian group (e.g., Urodela) could be sufficiently protective of another (e.g., Anura) and/or whether some nonamphibian aquatic taxonomic groups (e.g., fish or aquatic invertebrates) may be representative of aquatic amphibian life stages. This scope is intended to be a guide in the development of methods that would yield data appropriate for ecological risk decisions applicable to amphibians. Integr Environ Assess Manag 2017;13:601-613. © 2016 SETAC.

Toxicity of clomazone and its formulations to zebrafish embryos (Danio rerio)

Herbicides are the most widely used group of pesticides but after reaching water bodies they are able to cause adverse effects on non-target organisms. Different formulations using the same active ingredient are frequently available, which raises the issue of potential influence of different formulation types on herbicide toxicity. The present study evaluated the toxicity and teratogenic effects of the active ingredient clomazone and its two formulations (Rampa^® EC and GAT Cenit 36 CS, both containing 360g a.i./l of clomazone) on zebrafish embryos. The crucial difference between the two formulation types is the way of active substance release. This investigation is the first report on zebrafish embryotoxicity of both clomazone and its formulations. The technical active ingredient and formulations caused mortality and diverse teratogenic effects, showing different levels of toxicity. The LC₅₀ values for the technical ingredient, Rampa^® EC and GAT Cenit 36 CS were 61.4, 9.6 and 92.5mg a.i./l, respectively. Spontaneous movements in 22 hpf embryos decreased under exposure to both the technical ingredient and formulations. A significant number of underdeveloped embryos was detected after exposure to clomazone and Rampa^® EC, while no underdevelopment was noted in embryos exposed to GAT Cenit 36 CS. Exposure to the technical ingredient and formulations led also to a series of morphological changes and interfered with the growth of zebrafish embryos. The EC₅₀ based on detection of edemas, spine and tail tip deformations and gas bladder absence (120hpf) was 12.1, 10.1 and 24.1mg/l for technical clomazone, Rampa^® EC and GAT Cenit 36 CS, while teratogenicity index (TI) based on LC₅₀/EC₅₀ ratio was 5.1, 1 and 3.8, respectively. The data in this study showed that the emulsifiable concentrate formulation (Rampa^® EC) caused statistically significantly higher toxicity, and the aqueous capsule suspension (GAT Cenit 36 CS) lower toxicity than technical clomazone. It indicates that different formulations with the same active ingredient may have different environmental impacts, which is why risk assessment based only on active ingredient toxicity might not be sufficient in terms of preventing formulation effects on the environment.

Age-dependent changes in sensitivity to a pesticide in tadpoles of the common toad (Bufo bufo)

The worldwide en masse application of pesticides and the frequently reported malign effects on several non-target organisms underpin the importance of ecotoxicological research on these anthropogenic pollutants. Previous studies showed that sensitivity to herbicides can vary widely depending on additional stress factors, on the species and even on the population investigated. However, there is little information about how sensitivity changes during ontogeny, and how the duration of exposure is linked to the magnitude of malign effects, even though this knowledge would be important for the interpretation of toxicity test results and for formulating recommendations regarding the timing of pesticide application. We exposed tadpoles of the common toad (Bufo bufo) to three concentrations (0, 2 and 4mg a.e./L) of a glyphosate-based herbicide during the 1st, 2nd, 3rd, 4th, or 5th period of larval development or during the entire experiment, and measured survival, time until metamorphosis and body mass at metamorphosis to estimate fitness-consequences. Younger tadpoles were more sensitive to the herbicide in all measured traits than older ones, and this age-dependence was especially pronounced at the high herbicide concentration. Furthermore, tadpoles exposed to the herbicide during the entire experiment developed slower than tadpoles exposed only early on, but we did not observe a similar effect either on body mass or survival. The observed age-dependence of sensitivity to herbicides draws attention to the fact that results of toxicity tests obtained for one age-class are not necessarily generalizable across ontogeny. Also, the age of test animals has to be considered when planning ecotoxicological studies and interpreting their results. Finally, taking into account the temporal breeding habits of local amphibians when planning pesticide application would be highly favourable: if tadpoles would not get exposed to the herbicide during their most sensitive early development, they would sustain less anthropogenic damage from our efforts of controlling weeds.

Effects of a glyphosate-based herbicide and predation threat on the behaviour of agile frog tadpoles

The widespread application of pesticides emphasises the importance of understanding the impacts of these chemicals on natural communities. The most commonly applied broad-spectrum herbicides in the world are glyphosate-based herbicides, which have been suggested to induce significant behavioural changes in non-target organisms even at low environmental concentrations. To scrutinize the behavioural effects of herbicide-exposure we exposed agile frog (Rana dalmatina) tadpoles in an outdoor mesocosm experiment to three concentrations of a glyphosate-based herbicide (0, 2 and 6.5mg acid equivalent (a.e.) / L). To assess whether anti-predator behaviour is affected by the pesticide, we combined all levels of herbicide-exposure with three predator treatments (no predator, caged Aeshna cyanea dragonfly larvae or Lissotriton vulgaris newt adults) in a full factorial design. We observed hiding, activity, proximity to the predator cage and vertical position of tadpoles. We found that at the higher herbicide concentration tadpoles decreased their activity and more tadpoles were hiding, and at least at the lower concentration their vertical position was closer to the water surface than in tadpoles of the control treatment. Tadpoles also decreased their activity in the presence of dragonfly larvae, but did not hide more in response to either predator, nor did tadpoles avoid predators spatially. Further, exposure to the herbicide did not significantly influence behavioural responses to predation threat. Our study documents a definite influence of glyphosate-based herbicides on the behaviour of agile frog tadpoles and indicates that some of these changes are similar to those induced by dangerous predators. This may suggest that the underlying physiological mechanisms or the adaptive value of behavioural changes may similar.

Sub-lethal effects of a glyphosate-based commercial formulation and adjuvants on juvenile oysters (Crassostrea gigas) exposed for 35days

Glyphosate-based herbicides include active matter and adjuvants (e.g. polyethoxylated tallow amines, POEAs). In addition to a previous investigation on the effect of glyphosate on oysters, the aim of the present study was to investigate the effects of sub-chronic exposures (35days) to three concentrations (0.1, 1 and 100μgL-1) of Roundup Express® (REX) and POEAs on oysters belonging to the same age group. Low mortality rates were calculated, and only few significant differences (i.e. shell length) between exposure conditions were observed at a given date. However, when comparing the biomarker's temporal variations, some different patterns (e.g. condition index, reproduction, parameters of oxidative stress) were observed depending on the molecules and concentrations. These results suggest that a longer exposure to an environmental concentration (0.1μgL-1) of REX and POEAs could induce harmful effects on oysters.

Complex interactive effects of water mold, herbicide, and the fungus Batrachochytrium dendrobatidis on Pacific treefrog Hyliola regilla hosts

Infectious diseases pose a serious threat to global biodiversity. However, their ecological impacts are not independent of environmental conditions. For example, the pathogenic fungus Batrachochytrium dendrobatidis (Bd), which has contributed to population declines and extinctions in many amphibian species, interacts with several environmental factors to influence its hosts, but potential interactions with other pathogens and environmental contaminants are understudied. We examined the combined effects of Bd, a water mold (Achlya sp.), and the herbicide Roundup® Regular (hereafter, Roundup®) on larval Pacific treefrog Hyliola regilla hosts. We employed a 2 wk, fully factorial laboratory experiment with 3 ecologically realistic levels (0, 1, and 2 mg l-1 of active ingredient) of field-formulated Roundup®, 2 Achlya treatments (present and absent), and 2 Bd treatments (present and absent). Our results were consistent with sublethal interactive effects involving all 3 experimental factors. When Roundup® was absent, the proportion of Bd-exposed larvae infected with Bd was elevated in the presence of Achlya, consistent with Achlya acting as a synergistic cofactor that facilitated the establishment of Bd infection. However, this Achlya effect became nonsignificant at 1 mg l-1 of the active ingredient of Roundup® and disappeared at the highest Roundup® concentration. In addition, Roundup® decreased Bd loads among Bd-exposed larvae. Our study suggests complex interactive effects of a water mold and a contaminant on Bd infection in amphibian hosts. Achlya and Roundup® were both correlated with altered patterns of Bd infection, but in different ways, and Roundup® appeared to remove the influence of Achlya on Bd.

Potential risks to freshwater aquatic organisms following a silvicultural application of herbicides in Oregon's Coast Range

Glyphosate, aminomethylphosphonic acid (AMPA), imazapyr, sulfometuron methyl (SMM), and metsulfuron methyl (MSM) were measured in streamwater collected during and after a routine application of herbicides to a forestry site in Oregon's Coast Range. Samples were collected at 3 stations: HIGH at the fish-no-fish interface in the middle of the harvest and spray unit, MID at the bottom of the unit, and LOW downstream of the unit. All herbicides were applied by helicopter in a single tank mix. AMPA, imazapyr, SMM, and MSM were not detected (ND) in any sample at 15, 600, 500, and 1000 ng/L, respectively. A pulse of glyphosate peaking at approximately equal to 62 ng/L manifested at HIGH during the application. Glyphosate pulses peaking at 115 ng/L (MID) and 42 ng/L (HIGH) were found during the first 2 postapplication storm events 8 and 10 days after treatment (DAT), respectively: glyphosate was less than 20 ng/L (ND) at all stations during all subsequent storm events. All glyphosate pulses were short-lived (4-12 h). Glyphosate in baseflow was approximately equal to 25 ng/L at all stations 3 DAT and was still approximately equal to 25 ng/L at HIGH, but ND at the other stations, 8 DAT: subsequently, glyphosate was ND in baseflow at all stations. Aquatic organisms were subjected to multiple short-duration, low-concentration glyphosate pulses corresponding to a cumulative time-weighted average (TWA) exposure of 6634 ng/L × h. Comparisons to TWA exposures associated with a range of toxicological endpoints for sensitive aquatic organisms suggests a margin of safety exceeding 100 at the experimental site, with the only potential exception resulting from the ability of fish to detect glyphosate via olfaction. For imazapyr, SMM, and MSM the NDs were at concentrations low enough to rule out effects on all organisms other than aquatic plants, and the low concentration and (assumed) pulsed nature of any exposure should mitigate this potential. Integr Environ Assess Manag 2017;13:396-409. © 2016 SETAC.

Aquatic hazard assessment of MON 0818, a commercial mixture of alkylamine ethoxylates commonly used in glyphosate-containing herbicide formulations. Part 2: Roles of sediment, temperature, and capacity for recovery following a pulsed exposure

A series of toxicity tests with MON 0818, a commercial surfactant mixture of polyoxyethylene tallow amines, were performed: 1) in the presence of sediment for benthic invertebrates and fish: 2) to examine the recovery capacity of Daphnia magna and 4 primary producers after a pulsed (24-h) exposure; and 3) to examine the potential effect of increased water temperature on toxicity of MON 0818 to 2 cold-water fishes. In the presence of sediment, no acute (24-h) mortality was observed for 3 of the 5 species up to 10 mg L-1 . The median effective concentrations for the other 2 species were significantly greater than for water only tests. The EC50 at 15 °C for Salvelinus alpinus was statistically lower than that at 10 °C. Latent effects of a 24-h exposure (1 mg L-1 ) were observed for Rhabdocelis subcapitata and Chlorella vulgaris, as indicated by delayed growth during recovery phase; however, both cultures were able to recover, as indicated by a lack of changes in maximum absolute growth rates. No significant effects of a 24-h exposure to MON 0818 were observed for Oophila sp. (1.5 mg L-1 ) or Lemna minor (100 mg L-1 ). Latent mortality after a 24-h exposure to 5 mg L-1 was observed during the recovery phase for D. magna; however, reproduction endpoints on surviving individuals were not altered. The results indicate that quick dissipation of MON 0818 in the presence of sediment can reduce the effects on exposed organisms, and that full recovery from 24-h exposures to concentrations of MON 0818 equal to, or greater than, those expected in the environment is possible. Environ Toxicol Chem 2017;36:512-521. © 2016 SETAC.

Effects of insecticides on a phytotelmata-breeding amphibian

Information on the impact of pesticides on amphibian species breeding in phytotelmata (water bodies within plants) is totally lacking. The aim of the present study was to assess the impact of the insecticide malathion on larvae of Phyllodytes luteolus. Individuals were exposed to ecologically relevant concentrations of malathion (commercial formulation) for 16 d under laboratory conditions. Malathion had a lethal effect that allowed the authors to hypothesize that phtytotelmata-breeding species are likely as vulnerable to pollution as pond breeders. Environ Toxicol Chem 2017;36:422-428. © 2016 SETAC.

The effect of glyphosate-based herbicide Roundup and its co-formulant, POEA, on the motoric activity of rat intestine - In vitro study

The study was aimed at evaluating the effect of Roundup, polyoxyethylene tallow amine (POEA) and mixture of glyphosate and POEA in different levels on the motoric activity of jejunum strips. The incubation in the Roundup solutions caused a significant, mostly miorelaxant, reversible reaction of smooth muscle; only in the highest tested dose which is equivalent to the agricultural concentration (1% corresponding to 1.7g glyphosate/L) there was an irreversible disturbance of the spontaneous contractility and reactivity. The incubation in POEA solutions in the range of low doses (0.256; 1.28; 6.4mg/L) resulted in a biphasic muscle reaction (relaxation and contraction); whereas in the range of high doses, i.e. 32; 160 and 800mg/L (agricultural spray concentrations) induced only a miorelaxant, irreversible response. The results indicate very high toxicity of POEA which exceeds the toxicity of the commercial formulations. Besides, it is postulated that glyphosate and POEA may display antagonistic interaction towards the motoric activity of gastrointestinal tract.

Evaluation of Stage-Dependent Genotoxic Effect of Roundup® (Glyphosate) on Caiman latirostris Embryos

The agricultural expansion over the past decades, along with the associated increase in the use of pesticides, represents a high risk for many wild species. Caiman latirostris is a South American caiman with many features that make it highly vulnerable to pesticide exposure. Considering previous finding on the genotoxicity of the glyphosate-based formulation Roundup® in this species, the aim of this study was to evaluate the possible stage-dependent effect of this compound on C. latirostris embryos through the Comet assay (CA), micronuclei (MN), and nuclear abnormalities (NA) tests. Caiman eggs were exposed to three effective concentrations of Roundup® (750, 1250, 1750 µg/egg) in three different stages of the incubation period (total duration 70 ± 3 days at 31 ± 2 °C) of approximately 23 days each. A statistically significant difference in DNA damage determined by the CA was found between groups exposed to different concentrations of RU (p < 0.05) and the negative control, but no difference was observed among the three stages of exposure within any treatment (p > 0.05). There was no differences in the MN or NA frequencies between the different groups and the negative control (p > 0.05), nor among the different stages within each treatment. The results obtained in this study indicate that RU produce DNA damage on C. latirostris embryos independently of the developmental stage where the exposure occurs, implying an important risk for the species during all its period of development, when pesticide application is at maximum rate.

Population and life-stage-specific effects of two herbicide formulations on the aquatic development of European common frogs (Rana temporaria)

Environmental contamination is suggested to contribute to amphibian population declines. However, the effects of a contaminant on a particular amphibian species can differ among populations. The authors investigated the toxic effects of 2 herbicide formulations on different populations and on representative developmental stages of the European common frog (Rana temporaria). Larvae from forest populations were more sensitive to a commonly used glyphosate-based herbicide compared with individuals from agrarian land. Median lethal concentrations correlated with measured glyphosate levels in the breeding ponds, which may be a sign of evolved tolerances. The reverse result was observed for a less commonly used cycloxydim-based herbicide. Effects of the glyphosate-based herbicide were stronger for earlier larval stages compared with later larval stages. Hence, applications in early spring (when early larvae are present in breeding ponds) pose greater risk concerning acute toxic effects on R. temporaria. With regard to late larval stages, short exposure (96 h) of prometamorphic larvae prolonged time to metamorphosis, but only at the highest test concentration that did not significantly induce mortality. This could be due to impairment of the thyroid axis. Notably, nearly all test concentrations of the 2 herbicides provoked growth retardation. Further research on how evolved or induced tolerances are acquired, actual contamination levels of amphibian habitats, and potential endocrine effects of glyphosate-based herbicides is necessary. Environ Toxicol Chem 2017;36:190-200. © 2016 SETAC.

Effects of a commonly used glyphosate-based herbicide formulation on early developmental stages of two anuran species

Environmental contamination, especially due to the increasing use of pesticides, is suggested to be one out of six main reasons for the global amphibian decline. Adverse effects of glyphosate-based herbicides on amphibians have been already discussed in several studies with different conclusions, especially regarding sublethal effects at environmentally relevant concentrations. Therefore, we studied the acute toxic effects (mortality, growth, and morphological changes) of the commonly used glyphosate-based herbicide formulation Roundup® UltraMax on early aquatic developmental stages of two anuran species with different larval types (obligate vs. facultative filtrating suspension feeders), the African clawed frog (Xenopus laevis) and the Mediterranean painted frog (Discoglossus pictus). While X. laevis is an established anuran model organism in amphibian toxicological studies, we aim to establish D. pictus as another model for species with facultative filtrating larvae. A special focus of the present study lies on malformations in X. laevis embryos, which were investigated using histological preparations. In general, embryos and larvae of X. laevis reacted more sensitive concerning lethal effects compared to early developmental stages of D. pictus. It was suggested, that especially the different morphology of their filter apparatus and the higher volume of water pumped through the buccopharynx of X. laevis larvae lead to higher exposure to the formulation. The test substance induced similar lethal effects in D. pictus larvae as it does in the teleost standard test organism used in pesticide approval, the rainbow trout (Oncorhynchus mykiss), whereas embryos of both species are apparently more tolerant and, conversely, X. laevis larvae about two times more sensitive. In both species, early larvae always reacted significantly more sensitive than embryos. Exposure to the test substance increased malformation rates in embryos of both species in a concentration-dependent manner, but not at environmentally relevant concentrations. However, the assumed field safety, based on calculated surface water concentrations of the active ingredient (glyphosate), should be validated with realistic field data and buffer strips have to be urgently regarded to any aquatic amphibian habitat.

Effect on the growth and development and induction of abnormalities by a glyphosate commercial formulation and its active ingredient during two developmental stages of the South-American Creole frog, Leptodactylus latrans

We evaluated the acute lethal and sublethal effects of technical-grade glyphosate (GLY) and the GLY-based commercial formulation Roundup ULTRA MAX® (RU) on two Gosner stages (Gss) 25 and 36 of the South-American Creole frog, Leptodactylus latrans. Bioassays were performed following standardized methods within a wide range of concentrations (0.0007-9.62 mg of acid equivalents per liter-a.e./L-of RU and 3-300 mg/L of GLY). The endpoints evaluated were mortality, swimming activity, growth, development, and the presence of morphologic abnormalities, especially in the mouthparts. No lethal effects were observed on larvae exposed to GLY during either Gs-25 or Gs-36. The concentrations inducing 50 % lethality in RU-exposed larvae at different exposure times and Gss ranged from 3.26 to 9.61 mg a.e./L. Swimming activity was affected by only RU. Effects on growth and development and the induction of morphologic abnormalities-like oral abnormalities and edema-were observed after exposure to either GLY or RU. Gs-25 was the most sensitive stage to both forms of the herbicide. The commercial formulation was much more toxic than the active ingredient on all the endpoints assessed. Effects on growth, development, and the induction of morphologic abnormalities observed in the range of environmental concentrations reported for agroecosystems of Argentina constitute an alert to the potential detrimental effects of the herbicide that could be affecting the fitness and survival of anurans in agroecosystems.

Non-target effects of a glyphosate-based herbicide on Common toad larvae (Bufo bufo, Amphibia) and associated algae are altered by temperature

BACKGROUND

Glyphosate-based herbicides are the most widely used pesticides in agriculture, horticulture, municipalities and private gardens that can potentially contaminate nearby water bodies inhabited by amphibians and algae. Moreover, the development and diversity of these aquatic organisms could also be affected by human-induced climate change that might lead to more periods with extreme temperatures. However, to what extent non-target effects of these herbicides on amphibians or algae are altered by varying temperature is not well known.

METHODS

We studied effects of five concentrations of the glyphosate-based herbicide formulation Roundup PowerFlex (0, 1.5, 3, 4 mg acid equivalent glyphosate L-1 as a one time addition and a pulse treatment of totally 4 mg a.e. glyphosate L-1) on larval development of Common toads (Bufo bufo, L.; Amphibia: Anura) and associated algae communities under two temperature regimes (15 vs. 20 °C).

RESULTS

Herbicide contamination reduced tail growth (-8%), induced the occurrence of tail deformations (i.e. lacerated or crooked tails) and reduced algae diversity (-6%). Higher water temperature increased tadpole growth (tail and body length (tl/bl) +66%, length-to-width ratio +4%) and decreased algae diversity (-21%). No clear relation between herbicide concentrations and tadpole growth or algae density or diversity was observed. Interactive effects of herbicides and temperature affected growth parameters, tail deformation and tadpole mortality indicating that the herbicide effects are temperature-dependent. Remarkably, herbicide-temperature interactions resulted in deformed tails in 34% of all herbicide treated tadpoles at 15 °C whereas no tail deformations were observed for the herbicide-free control at 15 °C or any tadpole at 20 °C; herbicide-induced mortality was higher at 15 °C but lower at 20 °C.

DISCUSSION

These herbicide- and temperature-induced changes may have decided effects on ecological interactions in freshwater ecosystems. Although no clear dose-response effect was seen, the presence of glyphosate was decisive for an effect, suggesting that the lowest observed effect concentration (LOEC) in our study was 1.5 mg a.e. glyphosate L-1 water. Overall, our findings also question the relevance of pesticide risk assessments conducted at standard temperatures.

Recent advances in M13 bacteriophage-based optical sensing applications

Recently, M13 bacteriophage has started to be widely used as a functional nanomaterial for various electrical, chemical, or optical applications, such as battery components, photovoltaic cells, sensors, and optics. In addition, the use of M13 bacteriophage has expanded into novel research, such as exciton transporting. In these applications, the versatility of M13 phage is a result of its nontoxic, self-assembling, and specific binding properties. For these reasons, M13 phage is the most powerful candidate as a receptor for transducing chemical or optical phenomena of various analytes into electrical or optical signal. In this review, we will overview the recent progress in optical sensing applications of M13 phage. The structural and functional characters of M13 phage will be described and the recent results in optical sensing application using fluorescence, surface plasmon resonance, Förster resonance energy transfer, and surface enhanced Raman scattering will be outlined.

Glyphosate induces cardiovascular toxicity in Danio rerio

Glyphosate is a broad spectrum herbicide used aggressively in agricultural practices as well as home garden care. Although labeled "safe" by the chemical industry, doses tested by industry do not mimic chronic exposures to sublethal doses that organisms in the environment are exposed to over long periods of time. Given the widespread uses of and exposure to glyphosate, studies on developmental toxicity are needed. Here we utilize the zebrafish vertebrate model system to study early effects of glyphosate on the developing heart. Treatment by embryo soaking with 50μg/ml glyphosate starting at gastrulation results in structural abnormalities in the atrium and ventricle, irregular heart looping, situs inversus as well as decreased heartbeats by 48h as determined by live imaging and immunohistochemistry. Vasculature in the body was also affected as determined using fli-1 transgenic embryos. To determine if the effects noted at 48h post fertilization are due to early stage alterations in myocardial precursors, we also investigate cardiomyocyte development with a Mef2 antibody and by mef2ca in situ hybridization and find alterations in the Mef2/mef2ca staining patterns during early cardiac patterning stages. We conclude that glyphosate is developmentally toxic to the zebrafish heart.

Effects of glyphosate and the glyphosate based herbicides Roundup Original(®) and Roundup Transorb(®) on respiratory morphophysiology of bullfrog tadpoles

Glyphosate-based herbicides are widely used in agriculture and are commonly found in water bodies. Roundup Original(®) (RO) contains an isopropylamine glyphosate (GLY) salt containing the surfactant POEA, while Roundup Transorb R(®) (RTR) contains a potassium salt of GLY with unknown surfactants. Both contain different compositions of so-called "inert" ingredients, more toxic than glyphosate. Amphibian tadpoles often experience variations in O2 availability in their aquatic habitats; an ability to tolerate hypoxia can condition their survival and fitness. We evaluated the impacts of sublethal concentrations of GLY (1 mg L(-1)), RO (1 mg L(-1) GLY a.e) and RTR (1 mg L(-1) GLY a.e) on metabolic rate (V·O2 - mLO2 Kg1 h(-1)) of bullfrog tadpoles during normoxia and graded hypoxia, and related this to morphology of their skin, their major site of gas exchange. In control (CT) V·O2 remained unaltered from normoxia until 40 mmHg, indicating a critical O2 tension between 40 and 20 mmHg. GLY significantly reduced V·O2, possibly due to epidermal hypertrophy, which increased O2 diffusion distance to O2 uptake. In contrast, RTR increased V·O2 during hypoxia, indicating an influence of "inert" compounds and surfactants. V·O2 of RO did not differ from CT, suggesting that any increase in V·O2 caused by exposure was antagonized by epidermal hypertrophy. Indeed, all herbicides caused marked alterations in skin morphology, with cell and epithelium wall presenting hyperplasia or hypertrophy and chromatid rupture. In summary, GLY, RO and RTR exert different effects in bullfrog tadpoles, in particular the surfactants and inert compounds appear to influence oxygen uptake.

Unintended effects of the herbicides 2,4-D and dicamba on lady beetles

Weed resistance to glyphosate and development of new GM crops tolerant to 2,4-dichlorophenoxyacetic acid (2,4-D) and dicamba is expected to lead to increased use of these herbicides in cropland. The lady beetle, Coleomegilla maculata is an important beneficial insect in cropland that is commonly used as an indicator species in safety evaluations of pesticides. Here, we examined the lethal and non-lethal effects of 2,4-D and dicamba active ingredients and commercial formulations to this lady beetle species, and tested for synergistic effects of the herbicides. Second instars of lady beetles were exposed to an experimental treatment, and their mortality, development, weight, sex ratio, fecundity, and mobility was evaluated. Using similar methods, a dose-response study was conducted on 2,4-D with and without dicamba. The commercial formulation of 2,4-D was highly lethal to lady beetle larvae; the LC90 of this herbicide was 13 % of the label rate. In this case, the "inactive" ingredients were a key driver of the toxicity. Dicamba active ingredient significantly increased lady beetle mortality and reduced their body weight. The commercial formulations of both herbicides reduced the proportion of males in the lady beetle population. The herbicides when used together did not act synergistically in their toxicity toward lady beetles versus when the chemistries were used independently. Our work shows that herbicide formulations can cause both lethal and sublethal effects on non-target, beneficial insects, and these effects are sometimes driven by the "inactive" ingredients. The field-level implications of shifts in weed management practices on insect management programs should receive further attention.

Toxicities of glyphosate- and cypermethrin-based pesticides are antagonic in the tenspotted livebearer fish (Cnesterodon decemmaculatus)

Although pesticide contamination of surface waters normally occurs in the form of mixtures, the toxicity and interactions displayed by such mixtures have been little characterized until now. The present study examined the interactions prevailing in equitoxic and non-equitoxic binary mixtures of formulations of glyphosate (Glifoglex(®)) and cypermethrin (Glextrin(®)) to the tenspotted livebearer (Cnesterodon decemmaculatus), a widely distributed South American fish. The following 96 h-LC50s were obtained when pesticide formulations were tested individually: Glifoglex(®) 41.4 and 53 mg ae glyphosate/L; Glextrin(®) 1.89 and 2.60 μg cypermethrin/L. Equitoxic and non-equitoxic mixtures were significantly antagonic in all combinations tested. The magnitude of the antagonism (factor by which toxicity differed from concentration addition) varied between 1.37 and 3.09 times in the different non-equitoxic mixtures tested. Antagonism was due to a strong inhibition of cypermethrin toxicity by the glyphosate formulation, the toxicity of the cypermethrin-based pesticide being almost completely overridden by the glyphosate formulation. Results obtained in the current study with fish are radically opposite to those previously observed in tadpoles where synergy was observed when Glifoglex(®) and Glextrin(®) were present in mixtures (Brodeur et al., 2014).

Polyoxyethylene Tallow Amine, a Glyphosate Formulation Adjuvant: Soil Adsorption Characteristics, Degradation Profile, and Occurrence on Selected Soils from Agricultural Fields in Iowa, Illinois, Indiana, Kansas, Mississippi, and Missouri

Polyoxyethylene tallow amine (POEA) is an inert ingredient added to formulations of glyphosate, the most widely applied agricultural herbicide. POEA has been shown to have toxic effects to some aquatic organisms making the potential transport of POEA from the application site into the environment an important concern. This study characterized the adsorption of POEA to soils and assessed its occurrence and homologue distribution in agricultural soils from six states. Adsorption experiments of POEA to selected soils showed that POEA adsorbed much stronger than glyphosate; calcium chloride increased the binding of POEA; and the binding of POEA was stronger in low pH conditions. POEA was detected on a soil sample from an agricultural field near Lawrence, Kansas, but with a loss of homologues that contain alkenes. POEA was also detected on soil samples collected between February and early March from corn and soybean fields from ten different sites in five other states (Iowa, Illinois, Indiana, Missouri, Mississippi). This is the first study to characterize the adsorption of POEA to soil, the potential widespread occurrence of POEA on agricultural soils, and the persistence of the POEA homologues on agricultural soils into the following growing season.

Toxicological Risks of Agrochemical Spray Adjuvants: Organosilicone Surfactants May Not Be Safe

Agrochemical risk assessment that takes into account only pesticide active ingredients without the spray adjuvants commonly used in their application will miss important toxicity outcomes detrimental to non-target species, including humans. Lack of disclosure of adjuvant and formulation ingredients coupled with a lack of adequate analytical methods constrains the assessment of total chemical load on beneficial organisms and the environment. Adjuvants generally enhance the pesticidal efficacy and inadvertently the non-target effects of the active ingredient. Spray adjuvants are largely assumed to be biologically inert and are not registered by the USA EPA, leaving their regulation and monitoring to individual states. Organosilicone surfactants are the most potent adjuvants and super-penetrants available to growers. Based on the data for agrochemical applications to almonds from California Department of Pesticide Regulation, there has been increasing use of adjuvants, particularly organosilicone surfactants, during bloom when two-thirds of USA honey bee colonies are present. Increased tank mixing of these with ergosterol biosynthesis inhibitors and other fungicides and with insect growth regulator insecticides may be associated with recent USA honey bee declines. This database archives every application of a spray tank adjuvant with detail that is unprecedented globally. Organosilicone surfactants are good stand alone pesticides, toxic to bees, and are also present in drug and personal care products, particularly shampoos, and thus represent an important component of the chemical landscape to which pollinators and humans are exposed. This mini review is the first to possibly link spray adjuvant use with declining health of honey bee populations.

The effect of two glyphosate formulations on a small, diurnal lizard (Oligosoma polychroma)

Formulations of glyphosate-based herbicides continue to dominate the global herbicide market, while there continue to be concerns regarding the impact of this herbicide on non-target organisms. Research also indicates that the additives within certain glyphosate formulations, such as surfactants, are actually more toxic than the glyphosate active ingredient alone. Concerns arise in particular when glyphosate formulations are proposed for vegetation control in areas inhabited by rare or threatened species. Although the effect of glyphosate on birds and mammals is well studied, reptiles remain neglected in ecotoxicological studies. We investigated whether dermal exposure to two different commercial glyphosate formulations affected performance measures in the New Zealand common skink (Oligosoma polychroma). Fifty-eight skinks were each placed in a box of straw to simulate field conditions and sprayed once with Agpro Glyphosate 360, Yates Roundup Weedkiller (both at the label-specified concentrations of 144 mg glyphosate per 1 L water), or water (control). Agpro Glyphosate 360 contained ethoxylated tallow amine at a concentration of <200 g/L, while the surfactant within Yates Roundup Weedkiller was unknown. Following treatment skinks were kept in captivity and sampled for selected temperature and mass over a four-week period. Neither glyphosate formulation had a significant impact on mass. However, skinks treated with Yates Roundup Weedkiller selected significantly higher temperatures across 3 weeks following exposure. This heat-seeking behaviour could be a fever response to increase metabolism and thereby counteract physiological stress.

Side-Effects of Glyphosate to the Parasitoid Telenomus remus Nixon (Hymenoptera: Platygastridae)

The aim of this study was to compare the side-effects of glyphosate to the parasitoid Telenomus remus Nixon (Hymenoptera: Platygastridae) when parasitoids were exposed to this chemical at the pupal (inside host eggs) and adult stages. Bioassays were conducted under laboratory conditions according to the International Organization for Biological Control (IOBC) standard methods for testing side-effects of pesticides to egg parasitoids. Different glyphosate-based pesticides (Roundup Original®, Roundup Ready®, Roundup Transorb®, Roundup WG®, and Zapp Qi®) were tested at the same acid equivalent concentration. Treatments were classified following the IOBC toxicity categories as (1) harmless, (2) slightly harmful, (3) moderately harmful, and (4) harmful. When tested against T. remus adults, Roundup Original®, Roundup Ready®, Roundup Transorb®, and Roundup WG® reduced parasitism 2 days after parasitoid emergence, being classified as slightly harmful. Differently, when tested against T. remus pupae, all tested glyphosate-based products did not differ in their lethal effect and therefore did not reduce T. remus adult emergence or parasitism capacity, being classified as harmless. However, differences on sublethal toxicity were found. Parasitism of individuals emerging from parasitized eggs sprayed at the pupal stage of T. remus with Zapp Qi® was lower compared to control, but parasitism was still higher than 66%, and therefore, Zapp Qi® was still classified as harmless. In conclusion, all tested glyphosate-based products can be used in agriculture without negative impact to T. remus as none was classified as harmful or moderately harmful to this parasitoid when exposure occurred at the pupal or adult stages.