Roundup negatively impacts the behavior and nerve function of the Madagascar hissing cockroach (Gromphadorhina portentosa)

Alterations in microbiota-metabolism-circRNA crosstalk in autism spectrum disorder-like behaviours caused by maternal exposure to glyphosate-based herbicides in mice

Epidemiological evidence indicates exposure to glyphosate-based herbicides (GBHs) increases the risk for autism spectrum disorder (ASD). The gut microbiota has been found to influence ASD behaviours through the microbiota-gut-brain axis. However, the underlying links between early life GBH exposure and ASD-like phenotypes through the microbiota-gut-brain axis remain unclear. Therefore, we exposed mice to low-dose GBH (0.10, 0.25, 0.50, and 1.00 %) and determined the effects on ASD-like behaviours. Furthermore, three kinds of omics (gut microbiomics, metabolomics, and transcriptomics) were conducted to investigate the effects of GBH exposure on gut microbiota, gut metabolites, and circular RNAs (circRNAs) in the prefrontal cortex (PFC) using a cross-generational mouse model. Behavioural analyses suggested social impairment and repetitive/stereotypic behaviours in the GBH-exposed offspring. Furthermore, maternal exposure to glyphosate significantly altered the ASD-associated gut microbiota of offspring, and ASD-associated gut metabolites were identified. Specifically, we found that alterations in the gut microenvironment may contribute to changes in gut permeability and the blood-brain barrier, which are related to changes in the levels of circRNAs in the PFC. Our results suggest a potential effect of circRNAs through the disruption of the gut-brain interaction, which is an important factor in the pathogenesis of ASD in offspring induced by maternal exposure to GBH.

Effects of Low Concentration of Glyphosate-Based Herbicide on Genotoxic, Oxidative, Inflammatory, and Behavioral Meters in Danio rerio (Teleostei and Cyprinidae)

The glyphosate herbicide is a pesticide widely used in the world and can contaminate soil, air, and water. The objective of this work was to evaluate the toxicity of a glyphosate-based herbicide (GBH) in zebrafish (Danio rerio). Fish were exposed to different concentrations of GBH (0, 50, 250, and 500 µg/L) for 96 hours. Brain, liver, and blood were collected for biochemical and genotoxicity analyses, and behavioral tests were performed. The results showed that there was a reduction in the activity of the antioxidant enzymes of catalase (CAT) and glutathione-S-transferase (GST) in the liver at all concentrations and at the highest concentration in the brain. There was also a reduction in lipid peroxidation in the liver at all concentrations of glyphosate. There was an increase in micronuclei in the blood at the 500 µg/L concentration. However, the count of nuclear abnormalities showed no differences from the control. Interleukin-1beta (IL-1β) generation was inhibited at all concentrations in the liver and at the highest concentration in the brain. No significant differences were found in the behavioral test compared to the control. The results showed that acute exposure to GBH promoted an inflammatory event, which reduced the efficiency of antioxidants, thus producing a disturbance in tissues, mainly in the liver, causing immunosuppression and generating genotoxicity.

Limited effects of a glyphosate-based herbicide on the behaviour and immunity of males from six populations of the European earwig

The use of herbicides on crops often results in unintentional, low-dose exposure of non-target organisms, such as insects. While these exposures are increasingly known to alter the survival and physiology of insects, it remains unclear whether these effects can vary between populations and modify other fitness-related traits, such as behaviour and immunity. Here, we addressed these questions by testing the effects of sublethal exposure to a glyphosate-based herbicide (GBH) on the behaviour and immunity of European earwig males from six natural populations. We exposed each male to a dose of a common GBH (Roundup©) that was either recommended for crops, five times lower than that recommended for crops, or to a control solution. Twenty-four hours later, we measured the activity, boldness, and aggregation of each male. We then exposed them to an entomopathogenic fungus, monitored their survival for 6 weeks, and measured the immune response of the survivors. We found a condition-dependent effect of GBH exposure on male activity. Exposure to low doses induced a positive association between activity and weight, which was not observed in the high-dose and control groups. However, GBH had no effect on any of the other measured traits. All these results were consistent across the six populations tested, although we did find population-specific differences in almost all measurements on males. Further research is now needed to better understand the dose-response to GBH on male activity and its biological impact, as well as to evaluate the effectiveness of detoxification processes in this species. Overall, these results emphasise the importance of investigating the effects of herbicides on insects to expand our general understanding of the use and potential risks of plant protection products in integrated pest management programs.

Perfluorooctanoic acid induces behavioral impairment and oxidative injury in Nauphoeta cinerea nymphs

Perfluorooctanoic acid (PFOA) is a persistent organic contaminant with potential health threats to both animals and humans. However, the impact of PFOA on insects, which play significant roles in ecosystems, is understudied. We evaluated the toxicological impact of ecologically relevant concentrations of PFOA (0, 25, 50, 100, and 200 µg L-1) on Nauphoeta cinerea nymphs following exposure for 42 consecutive days. We analyzed the behavior of the insects with automated video-tracking software and processed the head, midgut, and fat body for biochemical assays. PFOA-exposed insects exhibited significant reductions in locomotory abilities and an increase in freezing time. Furthermore, PFOA exposure reduced acetylcholinesterase activity in the insect head. PFOA exposure increased the activities of superoxide dismutase, glutathione peroxidase, and catalase in the head and midgut, but decreased them in the fat body. PFOA also significantly increased glutathione-S transferase activity, while decreasing glutathione levels in the head, midgut, and fat body. Additionally, PFOA exposure increased reactive oxygen and nitrogen species, nitric oxide, lipid peroxidation, and protein carbonyl contents in the head, midgut, and fat body of the insects. In conclusion, our findings indicate that PFOA exposure poses an ecological risk to Nauphoeta cinerea.

Roundup and immune challenge have different effects on a native field cricket and its introduced competitor

Animals face many natural challenges, and humans have added to this burden by applying potentially harmful herbicides and unintentionally introducing competitors. We examine the recently introduced Velarifictorus micado Japanese burrowing cricket which shares the same microhabitat and mating season as the native Gryllus pennsylvanicus field cricket. In this study, we assess the combined effects of Roundup (glyphosate-based herbicide) and a lipopolysaccharide (LPS) immune challenge on both crickets. In both species, an immune challenge reduced the numbers of eggs that the female laid; however, this effect was much larger in G. pennsylvanicus. Conversely, Roundup caused both species to increase egg production, potentially representing a terminal investment strategy. When exposed to both an immune challenge and herbicide, G. pennsylvanicus fecundity was harmed more than V. micado fecundity. Furthermore, V. micado females laid significantly more eggs than G. pennsylvanicus, suggesting that introduced V. micado may have a competitive edge in fecundity over native G. pennsylvanicus. LPS and Roundup each had differing effects on male G. pennsylvanicus and V. micado calling effort. Overall, introduced male V. micado spent significantly more time calling than native G. pennsylvanicus, which could potentially facilitate the spread of this introduced species. Despite the population-level spread of introduced V. micado, in our study, this species did not outperform native G. pennsylvanicus in tolerating immune and chemical challenge. Although V. micado appears to possess traits that make this introduced species successful in colonizing new habitats, it may be less successful in traits that would allow it to outcompete a native species.

Roundup and glyphosate's impact on GABA to elicit extended proconvulsant behavior in Caenorhabditis elegans

As 3 billion pounds of herbicides are sprayed over farmlands every year, it is essential to advance our understanding how pesticides may influence neurological health and physiology of both humans and other animals. Studies are often one-dimensional as the majority examine glyphosate by itself. Farmers and the public use commercial products, like Roundup, containing a myriad of chemicals in addition to glyphosate. Currently, there are no neurological targets proposed for glyphosate and little comparison to Roundup. To investigate this, we compared how glyphosate and Roundup affect convulsant behavior in C.elegans and found that glyphosate and Roundup increased seizure-like behavior. Key to our initial hypothesis, we found that treatment with an antiepileptic drug rescued the prolonged convulsions. We also discovered over a third of nematodes exposed to Roundup did not recover from their convulsions, but drug treatment resulted in full recovery. Notably, these effects were found at concentrations that are 1,000-fold dilutions of previous findings of neurotoxicity, using over 300-fold less herbicide than the lowest concentration recommended for consumer use. Exploring mechanisms behind our observations, we found significant evidence that glyphosate targets GABA-A receptors. Pharmacological experiments which paired subeffective dosages of glyphosate and a GABA-A antagonist yielded a 24% increase in non-recovery compared to the antagonist alone. GABA mutant strain experiments showed no effect in a GABA-A depleted strain, but a significant, increased effect in a glutamic acid decarboxylase depleted strain. Our findings characterize glyphosate’s exacerbation of convulsions and propose the GABA-A receptor as a neurological target for the observed physiological changes. It also highlights glyphosate’s potential to dysregulate inhibitory neurological circuits.