4.1 Glyphosate exposure and mosquito life history traits
Exposure of larvae to the two realistic concentrations of glyphosate had no significant effect on mosquito size and other life history traits. Although our second experiment tended to show a slight effect of glyphosate (0.05mg/L) on larval development time, this was not observed in the first experiment even when the concentration of glyphosate in the rearing solution was doubled. These results are consistent with a recent study that found no effect of glyphosate on Aedes aegyptimosquito larvae at concentrations 20 times higher than ours (Baglan et al., 2018). In a pilot study, we even showed that a glyphosate concentration of 1g/L did not affect larval survival rate. In other aquatic invertebrate species, this molecule tends to have more significant effect. Glyphosate exposure, even at low concentration (0.1 - 0.05 mg/l), induced a reduction of juvenile size in the planktonic crustacean Daphnia magna (Cuhra et al., 2013) and negatively impacted the survival rate in the amphipod Hyalella castroi and the crayfish Cherax quadrinatus (Avigliano et al., 2014; Dutra et al., 2011). This suggests that mosquito larvae are more tolerant to glyphosate than other aquatic invertebrate species.