Potential use of Calotropis procera (milk weed) to control Culex quinquefasciatus (Diptera: Culicidae)

Culex quinquefasciatus cause severe biting nuisance and responsible for the spread of dreadful diseases among human beings. Biological researchers are trying to introduce eco-friendly products for the control of mosquitoes. The use of botanical pesticides has become very popular throughout the world as an alternative tool for the mosquito control. Present study deals with latex produced by the green parts of the Calotropis procera (milk weed) and aims to evaluate its toxic effects upon the mortality of C. quinquifasciatus larvae. Three concentrations (i.e., 0.5%, 0.25% and 0.1%) were tested against the larvae. There was significantly higher mortality in the treated group compared to the control group. The whole latex showed higher larval mortality for all concentrations at 24 h in lesser time compared to the rubber free latex. The percentage mortality was increased with increasing latex concentrations, indicating a direct relationship between the dose and percent mortality. Although the effectiveness of rubber free latex was less as compared to the whole latex but both types of latex caused 100% mortality within 24 h with 0.5% and 0.25% concentrations. When both types of latex were submitted to heat-treatment, the toxic effects were diminished considerably suggesting low thermo-stability of the toxic compounds. The results suggested that latex of C. procera can be used in mosquito control programs as it possesses remarkable larvicidal properties. However, it is recommended that effectiveness of the latex of C. procera should also be evaluated against other mosquito species especially against the Anopheles stephensi and Aedes agypti,which are growing threat in the country.