Ovicidal and larvicidal activity of the Impatiens rothii and Salvia officinalis extracts against Anopheles stephensi (Culicidae: Diptera) in laboratory conditions

Abstract Background Malaria vector control with synthetic insecticides can cause resistance, environmental toxicity, and harm to non-target animal species. To address these challenges, it is essential to explore safe, biodegradable, and environmentally friendly botanical alternatives for mosquito control. This study investigates the effects of crude root solvent extracts from Impatiens rothii and Salvia officinalis on Anopheles stephensi eggs and larvae under controlled laboratory conditions. Methods Fresh roots of Salvia officinalis and Impatiens rothii were collected separately, air dried, ground into a powder, and sieved. The powders were extracted using ethanol and chloroform solvent, and the resulting crude extracts were concentrated to prepare test solution at defined concentrations . Aquatain (AMF) was used as the standard control, while 20 Tween was used as the negative control . Larval mortality was measured after a 24-hour recovery period in each treatment group, and the hatchability of eggs was monitored after 48 hours. Statistical analyses were performed using R Studio to check normality and group differences, followed by SPSS for ANOVA comparison and probit regressions to calculate LC50 and LC90 values. Results There were significant differences (P < 0.05) in ovicidal and larvicidal activities between the treatment, negative, and standard control groups. The chloroform extract of S. officinalis (LC50 = 83.8 ppm; LC90 = 305.4 ppm) and the ethanol extract of I. rothii (LC50 = 64.7 ppm; LC90 = 214.28 ppm) demonstrated strong ovicidal activity. Additionally, the larvae treated with the ethanol extracts of I. rothii and S. officinalis presented the lowest larval mortality values, with LC50 and LC90 values of 124.6 ppm and 350.0 ppm, respectively. Aquatain AMF achieved 100% mortality, while Tween 20 showed no ovicidal or larvicidal effect. These findings suggest that early-stage mosquito control using botanical extracts may be more effective than adult-targeted interventions. Conclusion Root extracts of I. rothii and S. officinalis show promise as natural, eco-friendly alternatives to synthetic insecticides for controlling An. stephensi . Further research is needed to isolate active compounds, understand their mechanisms of action, and evaluate their safety and efficacy in field applications.