Becky Talyn

Glyphosate-based herbicides (GBHs) kill weeds and leaves around produce. GBHs elicit great concern because food residues and other exposures may affect human and environmental health. This study examines whether Roundup Super Concentrate (RSC), a GBH, affects activity levels, using Drosophila melanogaster (fruit flies) as a model system. Flies were exposed to RSC, glyphosate (gly), or polyethoxylated tallow amine (POEA), individually or in combination, at multiple ages and concentrations. Using a Drosophila Activity Monitor, we recorded activity levels from exposed and unexposed flies. Exposure to glyphosate and POEA, alone or in combination, did not affect their activity, indicating that other ingredients in the formulation are responsible for this effect. In addition, we examined several mechanisms of action. Flies were exposed to RSC treatments for two days before being released to the control medium to assess whether the effects of exposure were permanent or whether their activity levels could recover. Exposed flies exhibited less activity, especially females and especially at higher concentrations, while released flies only partially recovered. To examine metabolic mechanisms, we looked at whether RSC affected the protein content of individual Drosophila as a proxy for the overall nutritional condition but found no correlation. Neuromuscular defects were assessed using a negative geotaxis assay, which resulted in a correlation between activity and climbing. A reduction in activity is important for animal fitness because it impacts the ability to find food, find mates, and avoid predators.

Background/Objectives: As the incidence of autism spectrum disorder (ASD) and use of assisted reproductive technologies (ART) continue to rise in tandem, their relationship to one another, as well as the general risks of ART, are increasingly being explored. The purpose of this review is to summarize the literature on ASD risk, as well as the risks for other neurological and neurodevelopmental disorders, in children born following the implementation of ART. Methods: Here we review studies published between 2000−2023 that elucidate relationships between ASD and some of the most common forms of ART, including in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI), using fresh vs. frozen embryo transfer. Articles were identified by searching Google Scholar and PubMed databases. Results: Though some studies report adverse neurodevelopmental outcomes in ART-conceived children, such as ASD, attention-deficit/hyperactivity disorder (ADHD), and cerebral palsy, a majority of studies do not show a significant association between ART and neurodevelopmental disorders. Additionally, many confounding factors like multiple and preterm births, underlying infertility, and advanced parental age have been discussed, highlighting the need for studies that effectively control for these confounders. Potential mechanisms implicated in the pathogenesis of ASD, including epigenetic mechanisms of gene expression, that may be related to ART procedures, are also discussed. Conclusion: ART may pose a low additional risk to development of ASD, but confounding factors likely account for most of this risk. Several steps in the process of ART may cause epigenetic changes that are implicated in the development of ASD.

Use of glyphosate and glyphosate-based herbicides is ubiquitous in US agriculture and widespread around the world. Despite marketing efforts to the contrary, numerous studies demonstrate glyphosate toxicity to non-target organisms including animals, primarily focusing on mortality, carcinogenicity, renal toxicity, reproductive, and neurological toxicity, and the biochemical mechanisms underlying these physiological outcomes. Glyphosate toxicity also impacts animal behavior, both in model systems and in agricultural and environmentally relevant contexts. In this review, we examine the effects of glyphosate and glyphosate-based herbicides on animal behaviors, particularly activity, foraging and feeding, anti-predator behavior, reproductive behaviors, learning and memory, and social behaviors. Glyphosate can be detected both in food and in the environment, and avoided through activity and feeding strategies. However, exposure also reduces activity, depresses foraging and feeding, increases susceptibility to predation, interferes with courtship, mating, fertility and maternal behaviors, decreases learning and memory capabilities, and disrupts social behaviors. Changes in animal behavior as a result of glyphosate toxicity are important because of their sometimes severe effects on individual fitness, as well as ecosystem health. Implications for human behavior are also considered.

With the rise in concern about GMOs and pesticides on human health, we have utilized Drosophila melanogaster as a model organism for understanding the effects of Roundup-Ready^® GMO diets on health. We recorded dietary behavior during and after exposure to a medium containing GMO or non-GMO corn, Roundup^® in organic corn medium, and sucrose with or without one of the two Roundup^® formulations. No differences in behavior were observed when Drosophila were exposed to a medium containing Roundup-Ready^® GMO or non-GMO corn. Drosophila can detect and refrain from eating sucrose containing one Roundup^® formulation, Ready-to-Use, which contains pelargonic acid in addition to glyphosate as an active ingredient. Drosophila exhibited dose-dependent increased consumption of sucrose alone after exposure to a medium containing either Roundup^® formulation. This may indicate that flies eating a medium with Roundup^® eat less and were thus hungrier when then given sucrose solution; that a medium with Roundup^® is more difficult to digest; or that a medium with Roundup^® is less nutritious, as would be the case if nutritionally important microbes grew on control medium, but not one containing Roundup^®.

Herbicide use has increased dramatically since 2001, particularly Roundup^®. Effective in agricultural practice, Roundup^® adversely affects non-target organisms, including reproductive and endocrine systems. We exposed fruit flies, Drosophila melanogaster, to either Roundup^® Ready to Use, containing pelargonic acid and glyphosate, or Roundup^® Super Concentrate, that includes glyphosate and POEA, at sublethal concentrations. Both Roundup^® formulations reduced ovary volume with fewer mature oocytes, most adversely at the highest concentration tested. Flies exposed within 2 h of eclosion were affected more than at 4 h, suggesting a critical period of increased ovarian sensitivity. These results support multi-species evidence that glyphosate-based herbicides interfere with normal development of the reproductive systems of non-target organisms.

Genetically modified foods have become pervasive in diets of people living in the US. By far the most common genetically modified foods either tolerate herbicide application (HT) or produce endogenous insecticide (Bt). To determine whether these toxicological effects result from genetic modification per se, or from the increase in herbicide or insecticide residues present on the food, we exposed fruit flies, Drosophila melanogaster, to food containing HT corn that had been sprayed with the glyphosate-based herbicide Roundup^®, HT corn that had not been sprayed with Roundup^®, or Roundup^® in a variety of known glyphosate concentrations and formulations. While neither lifespan nor reproductive behaviors were affected by HT corn, addition of Roundup^® increased mortality with an LC₅₀ of 7.1 g/L for males and 11.4 g/L for females after 2 days of exposure. Given the many genetic tools available, Drosophila are an excellent model system for future studies about genetic and biochemical mechanisms of glyphosate toxicity.

In a wild-type strain of Drosophila melanogaster Meigen, the antijuvenoid precocene I reduced primary sexual receptivity in a dose-dependent manner; exposure to 0.80 μmol halved mating by virgin females in a 1-h test. Precocene-treated females rejected courting males for longer times than control females, but the rates of rejection signaling per unit time were unaffected. Precocene I slowed ovarian growth and markedly reduced oviposition; exposure to 0.14 μmol of precocene decreased oviposition by about half. Protein deprivation severely reduced ovarian volume and lowered primary receptivity in 3-d-old flies. Protein-starved females decamped from courting males more than yeast-fed females did at all the ages tested, whereas both age and diet affected the rates of stereotyped rejection signals. Precocene II did not affect sexual receptivity, whereas exposure to 70–140 μmol of ethoxyprecocene reduced sexual receptivity significantly.