Susceptibility of Culex quinquefasciatus (Say) Larvae to Methanolic Extracts of Annona reticulata.

<b>Background and Objective:</b> Environment pollution and resistance of many pests to the most frequently used chemical insecticides gave the rationale of altering to replace them with natural herbal extracts for pests and vector control. This study investigated the effect of methanolic extract of <i>Annona reticulata</i> on the mortality and development of larvae of <i>Culex quinquefasciatus</i>. <b>Materials and Methods:</b> Methanolic herbal extracts were analyzed using Reverse-Phase High-Performance Liquid Chromatography (RP-HPLC) to identify the phytochemical compounds in them. Ten mosquito larvae were used as replicates and exposed to each of the five concentrations of the plant extract (30, 100, 150, 200 and 250 mg mL¹) and ten larvae were exposed to double distilled water and considered as control. <b>Results:</b> Phytochemical analysis revealed the presence of phenols, steroids, quinones, tannins and saponins. Statistical analysis showed a significant strong correlation and regression between exposure to the different concentrations of the extract and mortality of <i>Culex quinquefasciatus</i> larvae where R² = 0.982, the Correlation value is 0.991099 (p<0.05). Results also showed that the extracts affect the development of larvae more than mortality. The effect of the extracts on the early larval stages was significantly high compared to the late stages of larvae. <b>Conclusion:</b> According to our knowledge results of this study has been reported for the first time in Saudi Arabia where <i>Annona reticulata</i> is neglected regionally and no study approved its efficacy as a botanical herbal extract against mosquitoes.

Evidence Based Efficacy of Selected Herbal Extracts Against Culex quinquefasciatus (Say) Larvae.

BACKGROUND AND OBJECTIVE: Chemical insecticides have some limitations in vectors control such as the emergence of resistance in vector mosquitoes to conventional synthetic insecticides. It aimed to evaluate the larvicidal efficacy and phytochemical potential of Azadirachta indica, Cymbopogon citratus and Allium sativum L. against ulex quinquefasciatus fourth instar larvae. MATERIAL AND METHODS: The plants were screened and evaluated for their phytochemical composition and larvicidal effects on . quinquefasciatus larvae. RESULTS: The bioassay results showed that the effects were dependent on time and concentration of the extract used. Results showed the least lethal dose value for ethanolic extract of . citrates (72 h exposure) and the highest value for aqueous extract of A. indica (24 h exposure). Chi-square values were significant at p<0.05. Phytochemical analysis showed phytochemicals such as alkaloids, flavonoids, cardiac glycosides and resins in all the three plants. However, tannins were absent in A. indica and A. sativum, while balsam was only present in A. indica. Saponins, balsam and phenols were not found in A. sativum. Phenols were also absent in . citratus. Terpenes, steroids and resins were absent A. indica. CONCLUSION: Findings of this study revealed that these herbal extracts constitute an effective eco-friendly approach for the control of . quinquefasciatus larvae.