Background: Mosquitoes transmit serious human diseases, causing millions of deaths every year. Use of synthetic insecticides to control vector mosquitoes has caused physiological resistance and adverse environmental effects in addition to high operational cost. Insecticides of botanical origin have been reported as useful for control of mosquitoes. Azadirachta indica (Meliaceae) and its derived products have shown a variety of insecticidal properties. The present paper discusses the larvicidal activity of neem-based biopesticide for the control of mosquitoes.

Azadirachta indica Juss. (family Meliaceae) is a vital plant with multiple agricultural and medicinal utilities. The seed cake after oil extraction can be a good source of nutrition in animal feed. The limitation to its use is the presence of azadirachtin, salannin, and other bitter constituents. To make it palatable for use as a source of animal nutrition it was detoxified using 50 and 80% methanol and was analyzed for contents of azadirachtin, salannin, and nutritional contents such as total carbohydrates, protein, crude fiber, in vitro protein digestibility, and trypsin inhibitor activity (TIA), prior to and after purification. The contents of azadirachtin and salannin were quantified using HPTLC and HPLC. Various validation parameters were also investigated. A highly significant decrease of antinutritional factor (TIA) was recorded after purification of samples, retaining the contents of protein, carbohydrates, crude fiber, and in vitro protein digestibility. The purified seed cake was found to be free of azadirachtin and salannin contents.

Background: Mosquitoes are an important public health concern as they spread life-threatening diseases such as malaria, filaria, Japanese encephalitis, dengue fever, chikungunya, and yellow fever. In the last decades, synthetic insecticides were extensively used for the control of these vector-borne diseases but it also reported the detrimental side-effects in human beings and pet animals. To overcome the side effects, plants-derived secondary metabolites were screened and tested for insecticidal properties. The present study deals with the insecticidal activity of chloroform and methanol extracts of Swertia celiata leaves against Culex quenquifasciatus, Aedes aegypti, and Anopheles stephensi larvae.Method: The S. celiata leaves were subjected to chloroform and methanol with 1:3 (Weight/ Volume) ratio and the extracted solvent was dried using rotary vacuum evaporator. The larvicidal activity of the extract was tested using WHO method and LC 50 and LC 90 were evaluated by probit analysis. Results:The LC 50 value of chloroform extract of S. celiata was found to be 65.288, 67.406 and 71.608 ppm whereas LC 90 was 184. 721, 186.582 and 192.497 ppm against C. quinquefasciatus, Ae. aegypti and A. stephensi, respectively. The methanolic extract was also found potent; LC 50 was 91.503, 101.574 and 99.104 ppm whereas LC 90 was 230.823, 271.927 and 234.257 ppm against C. quinquefasciatus, Ae. aegypti and A. stephensi, respectively. Both chloroform and methanol extract were found significantly lethal to the tested mosquito vectors. Conclusion:Taken results together, chloroform extract showed higher toxicity as compared to methanolic extract against all the tested species. The study clearly revealed that S. ciliata extract or bioactive compounds can be used as an alternative to synthetic insecticides.