Effect of polar crude extracts of the mexican prickly poppy on Culex quinquefasciatus mosquito larvae

Plant-derived natural products contain bioactive compounds. One notable example is Argemone mexicana L. (Papaveraceae), a weed native to Mexico that shows significant potential as a pest control agent. This study evaluated the larvicidal activity of aqueous extracts obtained from different plant parts of A. mexicana against the mosquito larvae of Culex quinquefasciatus (Say) (Diptera: Culicidae). The results revealed a clear dose-response relationship, indicating that higher concentrations led to increased larval mortality. In the first five days, the aqueous seed extract showed significant larvicidal efficacy. Probit regression analysis of the observed larval mortality during this period confirmed favorable toxicity, with a measured lethal concentration (LC₅₀) of 11.56 %. This indicates that only small amounts of the extract are required to induce 50 % larval mortality. Although the lethal concentration at 90 % (LC₉₀) was higher at 42.99 %, these values remain adequate for practical applications, particularly considering the product’s natural origin. During the same period, the flower extract also exhibited larvicidal effects, although with lower potency. Higher concentrations of the flower extract maintained significant mortality throughout the first five days. The root extract exhibited intermediate toxicity, with mortality levels proportional to concentration and sustained over time. In contrast, the stem and leaf extracts displayed limited larvicidal activity, even at elevated concentrations. At the end of the experiment (17-days), the extracts demonstrated significant toxicity, with mortality rates exceeding 70 % in all plant parts at the highest concentration tested (100 %). The highest mortality was observed for stem extracts, followed by leaf, and flower. The Relative Growth Index (RGI) confirmed the inhibitory effect of the extracts on larval development, with values below 0.6 in most treatments indicating a moderate response. The seed and root extracts caused the most significant disruption to larval growth. These findings suggest that A. mexicana could serve as a valuable botanical resource for disrupting the life cycle of C. quinquefasciatus and reducing its population. We need further research to optimize formulations and assess their applicability in sustainable vector control strategies because larvicidal efficacy varies depending on the plant part used.