BIO-EFFICACY OF INDIGENOUS NICOTIANA TABACUM EXTRACTS AT DIFFERENT SOLVENTS AGAINST THE DENGUE VECTOR AEDES AEGYPTI (DIPTERA: CULICIDAE)

Abstract

Dengue fever  remains a persistent health issue in various regions of Pakistan, particularly in urban areas where the Aedes aegypti vector is prevalent. This mosquito is a  key target for reducing the disease. Chemical insecticides have long been employed, but they face formidable hurdles, including pollution, damage to beneficial insects, and  health risks, as well as growing resistance in the host mosquitoes. This study investigates a more sustainable and readily available alternative, Nicotiana tabacum (tobacco) leaves, a plant widely used in traditional medicine. We have also tested the effects of different solvents: methanol, hexane, n-butanol, and water (over 24, 48, and 72 h; 200–600 ppm) on mosquito larvae, pupae, and eggs after the extraction of bioactive  compounds from the leaves. Mosquitoes were reared at the NIFA Medical Entomology lab in Peshawar under controlled conditions. According to the results summarized in Tables 4.2.1, 4.2.2, and 4.2.3, Nicotiana tabacum extracts demonstrated a highly significant, dose- and time-dependent biocidal effect against all developmental stages of Aedes aegypti, with methanol consistently proving to be the most potent solvent. At 600 ppm, methanolic extracts achieved complete larval mortality (100%) by 48 hours, drastically reduced egg hatching to 5%, and induced up to 95% pupal mortality by 72 hours, outperforming hexane, butanol, and aqueous extracts. The pronounced efficacy observed in methanol-based formulations, statistically supported by Tukey HSD analysis (p ≤ 0.05), highlights its superior ability to extract active phytochemicals with strong ovicidal, larvicidal, and pupicidal properties. These findings position methanolic N. tabacum extract at 600 ppm as a highly promising, eco-compatible biopesticide for integrated mosquito control strategies targeting multiple life stages of Aedes aegypti. Hexane and n-butanol extracts were also  effective, whereas water extracts appeared to be less effective. These results suggest that N. tabacum,  which is locally available in Pakistan, may play a significant role in eco-friendly mosquito control. If used as a botanical insecticide, it could mean less dependence on harmful chemicals and a local  tool for communities to fight dengue. This strategy aligns with the IVMM strategy and promotes sustainable  public health practices in Pakistan.