Background Malaria vector control with synthetic insecticides can cause resistance, environmental toxicity, and harm to non-target animal species. To address these issues, it is critical to investigate safe and environmentally friendly botanical extraction methods 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 environments. Methods Fresh roots of S. officinalis and I. rothii were collected separately, allowed to air dry, ground into a powder, and then sieved. The test plant powders were soaked in ethanol and chloroform solvent, and the extracted product was concentrated, forming a desired concentration solution for testing. Aquatain (AMF) was used as the standard control, while 3% of 20 Tween was used as the negative control. Larval mortality was measured after a 24 hours recovery period in each treatment group, and the hatchability of eggs was monitored after 48 hours. Statistical analyses were conducted using R Studio to check normality and identify significant differences between groups, then followed by SPSS, ANOVA to compare extract to standard group and probit regressions for LC50 and LC90 calculations. Results There were significant differences (P < 0.05) in ovicidal and larvicidal activities between the treatment, negative, and standard control groups. Both the chloroform extract of S. officinalis (LC50 and LC90 values of 83.8 and 305.4 ppm, respectively) and the ethanol extract of I. rothii (LC50 and LC90 values of 64.7 and 214.28 ppm, respectively) demonstrated low LC50 and LC90 values when tested against eggs. 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 reached 100%, whereas 3% of 20 Tween did not result in egg or larval mortality. Conclusion The study suggests that root extracts of I. rothii and S. officinalis can be a safe and effective alternative to synthetic mosquitocidal for controlling An. stephensi, suggesting early-stage mosquito control is more efficient than adult control. Further research is required to understand the essential ingredients, their mechanisms of action, efficacy, and safety in larger-scale applications.

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

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2026年4月25日

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Teresa Beyena,
Kidane Lelisa,
Belayhun Mendefro

摘要

Background

Malaria vector control with synthetic insecticides can cause resistance, environmental toxicity, and harm to non-target animal species. To address these issues, it is critical to investigate safe and environmentally friendly botanical extraction methods 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 environments.

Methods

Fresh roots of S. officinalis and I. rothii were collected separately, allowed to air dry, ground into a powder, and then sieved. The test plant powders were soaked in ethanol and chloroform solvent, and the extracted product was concentrated, forming a desired concentration solution for testing. Aquatain (AMF) was used as the standard control, while 3% of 20 Tween was used as the negative control. Larval mortality was measured after a 24 hours recovery period in each treatment group, and the hatchability of eggs was monitored after 48 hours. Statistical analyses were conducted using R Studio to check normality and identify significant differences between groups, then followed by SPSS, ANOVA to compare extract to standard group and probit regressions for LC₅₀ and LC₉₀ calculations.

Results

There were significant differences (P < 0.05) in ovicidal and larvicidal activities between the treatment, negative, and standard control groups. Both the chloroform extract of S. officinalis (LC₅₀ and LC₉₀ values of 83.8 and 305.4 ppm, respectively) and the ethanol extract of I. rothii (LC₅₀ and LC₉₀ values of 64.7 and 214.28 ppm, respectively) demonstrated low LC₅₀ and LC₉₀ values when tested against eggs. 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 reached 100%, whereas 3% of 20 Tween did not result in egg or larval mortality.

Conclusion

The study suggests that root extracts of I. rothii and S. officinalis can be a safe and effective alternative to synthetic mosquitocidal for controlling An. stephensi, suggesting early-stage mosquito control is more efficient than adult control. Further research is required to understand the essential ingredients, their mechanisms of action, efficacy, and safety in larger-scale applications.