Dietary Behavior of Drosophila melanogaster Fed with Genetically-Modified Corn or Roundup®.

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®.

Toxicological Effects of Roundup® on Drosophila melanogaster Reproduction.

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.

Roundup®, but Not Roundup-Ready® Corn, Increases Mortality of Drosophila melanogaster.

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.