RT Journal Article
SR Electronic
T1 Glyphosate Inhibits Melanization and Increases Susceptibility to Infection in Insects
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2020.05.20.105353
DO 10.1101/2020.05.20.105353
A1 Daniel F. Q. Smith
A1 Emma Camacho
A1 Raviraj Thakur
A1 Alexander J. Barron
A1 Yuemei Dong
A1 George Dimopoulos
A1 Nichole A. Broderick
A1 Arturo Casadevall
YR 2021
UL http://biorxiv.org/content/early/2021/02/22/2020.05.20.105353.abstract
AB Melanin, a black-brown pigment found throughout all kingdoms of life, has diverse biological functions including: UV protection, thermoregulation, oxidant scavenging, arthropod immunity, and microbial virulence. Given melanin’s broad roles in the biosphere, particularly in insect immune defenses, it is important to understand how exposure to ubiquitous environmental contaminants affects melanization. Glyphosate – the most widely used herbicide globally – inhibits melanin production, which could have wide-ranging implications in the health of many organisms, including insects. Here, we demonstrate that glyphosate has deleterious effects on insect health in two evolutionary distant species, Galleria mellonella (Lepidoptera: Pyralidae) and Anopheles gambiae (Diptera: Culicidae), suggesting a broad effect in insects. Glyphosate reduced survival of G. mellonella caterpillars following infection with the fungus Cryptococcus neoformans and decreased the size of melanized nodules formed in hemolymph, which normally help eliminate infection. Glyphosate also increased the burden of the malaria- causing parasite Plasmodium falciparum in A. gambiae mosquitoes, altered uninfected mosquito survival, and perturbed the microbial composition of adult mosquito midguts. Our results show that glyphosate’s mechanism of melanin inhibition involves antioxidant synergy and disruption of the reaction oxidation-reduction balance Overall, these findings suggest that glyphosate’s environmental accumulation could render insects more susceptible to microbial pathogens due to melanin inhibition, immune impairment, and perturbations in microbiota composition, potentially contributing to declines in insect populations.Competing Interest StatementThe authors have declared no competing interest.