Effect of the herbicide atrazine, tested as both an experimental and a commercial formulation, on the ovarian growth of the estuary crab Neohelice granulata.

SILVEYRA, GABRIELA R.; CANOSA, IVANA S.; MEDESANI, DANIEL A.; RODRIGUEZ, ENRIQUE M

San Diego

Congreso; Society of Toxicology 61st Annual Meeting and ToxExpo; 2022

Society of Toxicology (USA)

The herbicide atrazine (AT) is intensively applied to control weeds in corn, sorghum and sugar cane crops. This herbicide has been detected in areas adjacent to fields, reaching water courses by runoff and thus affecting the associated fauna. Prior studies in invertebrates, particularly crustaceans, have reported reproductive alterations linked to exposure to this herbicide. The present study was aimed at evaluating the in vivo effect of AT on ovarian growth, total content of vitellogenic proteins (Vg) and main energy reserves in Neohelice granulata crabs. Adult females collected from the Samborombón Bay (Province of Buenos Aires, Argentina) were used during the pre-reproductive period, when the ovarian growth peaks. Animals (n=15) were chronically exposed (90 days) to three sublethal concentrations (0.05, 0.5 and 5 mg/L) of AT, either as active principle of a commercial formulation (Gesaprim 90 WDG®; 90% active principle + 10% of not declared excipients), or as part of an experimental AT formulation (96% purity). A control group only maintained in saline water was also run. Every crab was isotaled in a glass container, under controlled conditions of feeding, aeration, temperature, and photoperiod. At the end of the assay, animals were anesthetized on ice water, and both the ovary and chelae muscle were dissected to measure different variables. We observed a significant decrease in total content of Vg, pre-vitellogenic and vitellogenic oocyte size, as well as a lower proportion of vitellogenic oocytes, in animals exposed to 5 mg/L of the commercial formulation, indicating a delay in ovarian maturation. A decrease in glycogen and protein levels in muscle was also observed, likely due to a compensatory effect of the stress induced by the exposure to the herbicide. Surprisingly, these results were not observed in females exposed to the experimental AT formulation. This differential toxicity between both formulations was likely associated with the presence of excipients in the commercial AT formulation. Taking together, our results could help to establish a baseline for predicting the effects produced by exposure to the Gesaprim 90 WDG® formulation, therefore being useful to revise the recommended guidelines for commercial AT formulations.