Mosquitocidal Activities of Cassia javanica Methanol Extract against the Dengue Vector Aedes aegypti

Dengue fever, transmitted by Aedes aegypti, remains a major public health concern, and the emergence of insecticide resistance necessitates the search for novel vector control agents. This study evaluated the multi-target bioefficacy of Cassia javanica methanol extract against all life stages of Ae. aegypti. The extract exhibited dose-dependent toxicity across larval instars, pupae, and adults. The highest larvicidal susceptibility was observed in first instar larvae (LC50 = 263.51 µg/mL), while pupae demonstrated the highest tolerance (LC50 = 440.92 µg/mL). Ovicidal assessment revealed a progressive decline in egg hatchability with increasing extract concentration; complete inhibition (no hatching) was recorded at 500 µg/mL, compared to 95.2% hatchability in the control. Adulticidal activity was also concentration-dependent, yielding an LC50 of 277.42 µg/mL after 24 hours of exposure. Furthermore, the extract provided notable repellent activity. At 500 ppm, the formulation offered 64.3% protection over 180 minutes post-application, whereas the lowest concentration (100 ppm) resulted in only 12.5% protection. Chi-square values (χ²) for all probit regression models were not significant (α = 0.05), indicating good fit of the data. The results clearly demonstrate that C. javanica methanol extract possesses potent and broad-spectrum activity against Ae. aegypti, affecting egg hatching, larval and pupal development, adult survival, and host-seeking repellency. These findings highlight the potential of C. javanica as a promising source of phyto-insecticidal compounds for integrated vector management strategies, particularly in combating insecticide-resistant mosquito populations.