Exploring the bioactive potential leaves of Sphaeranthus indicus: Targeting immature stages of Aedes aegypti and Culex quinquefasciatus mosquito vectors through bioassay-guided screening and fraction isolation.

Mosquito control is vital for combating mosquito-borne diseases, but concerns exist regarding the use of synthetic insecticides. This study aimed to explore eco-friendly alternatives derived from natural sources. The larvicidal, pupicidal, and ovicidal activities of various fractions obtained from the hexane leaf extract of Sphaeranthus indicus were investigated against two important mosquito vectors, Aedes aegypti and Culex quinquefasciatus. S. indicus leaves were extracted with hexane and column chromatography was performed with hexane, ethyl acetate, methanol, and their mixtures as eluents. Among the ten fractions (F1-F10) evaluated, fraction 'F-4' exhibited significant activity against third instar larvae, pupae, and eggs of both mosquito species, closely followed by 'F-5' . At a concentration of 10 ppm, 'F-4' achieved 100% mortality in larvae and displayed LC50 values of 5.08 ppm and 5.03 ppm for Ae. aegypti and Cx. quinquefasciatus larvae, respectively. The LC50 values for pupae were 6.12 ppm and 5.83 ppm for Ae. aegypti and Cx. quinquefasciatus, respectively. Regarding ovicidal activity, 'F-4' demonstrated percentages ranging from 63.2% to 64.8% against Ae. aegypti and Cx. quinquefasciatus eggs, respectively. These findings underscore the potent larvicidal, pupicidal, and ovicidal effects of fraction 'F-4' from S. indicus against the targeted mosquito species. Further research is warranted to identify the active compounds responsible for these effects and explore practical applications for sustainable mosquito control strategies.

Evaluating the Effectiveness of Pisonia alba Leaf Extracts in Managing Aedes aegypti and Culex quinquefasciatus Populations via Larvicidal, Pupicidal and Ovicidal Actions.

PURPOSE: The purpose of this study was to evaluate the effectiveness of Pisonia alba Span commonly known as lettuce tree or bird catcher tree leaf extracts in controlling Aedes aegypti and Culex quinquefasciatus mosquitoes, which transmit several severe illnesses, such as dengue, Zika, chikungunya, yellow fever, West Nile virus, lymphatic filariasis and Japanese encephalitis. METHODS: Sequential extraction of P. alba leaves was done using n-hexane, chloroform, and methanol. The larvicidal, pupicidal, and ovicidal activities of the extracts were evaluated against both mosquito species using standard bioassays. The concentrations of the extracts required to kill 50% of the mosquito larvae, pupae, and ova (LC50) were determined. RESULTS: The results showed that the methanol extract of P. alba had significant potential in killing the larvae, pupae, and ova of both mosquito species, with LC50 values of 65.0 and 54.5 ppm for larvicidal activity, 73.7 and 69.7 ppm for pupicidal activity, and 78.4 and 80.0 ppm for ovicidal activity against Ae. aegypti and Cx. quinquefasciatus, respectively. The n-hexane extract demonstrated moderate larvicidal activity, while the n-hexane and chloroform extracts lacked ovicidal activity. CONCLUSION: The methanol extract from Pisonia alba could be a natural and eco-friendly alternative for controlling mosquito populations responsible for transmitting vector-borne diseases. Further research is warranted to determine their practical applications in controlling mosquito populations in the field.

Mosquito larvicidal, pupicidal and ovicidal effects of the extracts of Peltophorum pterocarpum flowers on Aedes aegypti and Culex quinquefasciatus.

Mosquitoes are the vectors of several diseases like dengue, chikungunya, malaria etc. The three important mosquito species in India are Aedes aegypti, Culex quinquefasciatus and Anopheles stephensi. Several plant extracts have been tested for their anti-mosquito activity. In this dissertation, the larvicidal, pupicidal and ovicidal activities of the successive hexane, chloroform and methanol extracts of Peltophorum pterocarpum (Fabaceae) on mosquitoes are reported. The larvicidal activity of those extracts on both Aedes aegypti and Culex quinquefasciatus mosquitoes was found to be in a decreasing order of hexane, methanol and chloroform - the LC50 values for these extracts were 111.81 and 104.84 ppm, 121.92 and 121.56 ppm, 357.2 and 352.0 ppm respectively. Their pupicidal activity on both mosquitoes was found in the order of methanol, chloroform and hexane - the LC50 values for these extracts being 172.8 and 162.35 ppm, 425.8 respectively. Their ovicidal activity on both mosquitoes was found to be very low, even at the higher concentration of 500 ppm. This is the first report on the effect of the extracts of Peltophorum pterocarpum flowers on the two mosquito species of Aedes aegypti, Culex quinquefasciatus. In the present work, the results showed that the hexane extract had the highest larvicidal activity, while methanol showed the highest pupicidal activity besides larvicidal activity. Hence, the methanol extract holds promise to be used as mosquitocidal agent against the above two vectors.