Disease & Vector Studies III/Larval Control I
Disease & Vector Studies III/Larval Control I
Roundup® stands as one the world's most extensively utilized herbicide. A fraction of herbicides applied in agriculture fail to reach their intended targets, resulting in notable levels of these herbicides extending beyond agricultural boundaries. Glyphosate, the active ingredient in the Roundup® formulation, likewise exits its target sites through surface runoff, often being detected in aquatic systems. Prior studies have demonstrated that glyphosate can elicit biochemical, physiological, and behavioral modifications in non-target species, including mosquitoes.
Through laboratory experiments, we investigated the effect of a series of Roundup® doses on the development and survival of Culex quinquefasciatus, the main vector of WNV and SLE in southern California. Our result indicated that 1st instar larvae exposed to the high doses of Roundup® (500 and 1000 mg/l) experienced a high percentage of mortality and only a small fraction could molt into pupae. None of the pupae could eventually emerge as adults (n=10). Exposure to the low doses of Roundup®, similar to the field realistic doses, (0.1 mg and 1 mg/l) prolonged the larval duration and also reduced the mean of the daily count of live larvae, however the number of emerged adults was not impacted when compared with the control (n= 10). When 1st instar larvae were exposed to intermediate doses of Roundup®, no impact was observed on the mean of daily count of larvae at 10 mg/l concentration, but a significant reduction at the concentration of 100 mg/l was noted. Exposure to the intermediate doses of Roundup® also caused the larval stage to be prolonged considerably (n= 10).
This research indicates that the herbicide Roundup®, depending on the dose, can induce various effects on the immature stages of Cx. quinquefasciatus, which varies from prolonging the larval stage and reduction of population density in lower doses to the mortality in higher doses.