Larvicidal avtivity of stem extract of Cissus quadrangularis against the vector mosquitoes

Introduction Mosquitoes cause annoyance to man and other animals and affect health for centuries. These are the carriers of malaria, yellow fever, filariasis and encephalitis (Pfadt, 1978). Mosquito problem has become acute in recent years, though many programmes have been launched to control these vectors. Among these carriers, filarial mosquitoes are cosmopolitan and primary vector of filariasis in India and elsewhere (Gopalan et al., 1996) Moreover the distribution of mosquitoes are almost world wide as they range from equator nearly to the poles and from sea level to atleast 7000 feet altitude. Disease prevention by the control of mosquito has received more attention in medical entomology (Mani, 1982). Therefore, there is a crying need to check the population of vector mosquito in order to reduce vector borne disease using appropriate control measures (Service, 1983). One of the methods of control of mosquitoes is controlling them in their larval stage. Extensive research has been carried out on the control of mosquito larvae (Rajavel et al., 1987). The common methods available for the control of mosquitoes and agricultural pests are the use of insecticides. Chemical control methods using synthetic insecticides had been favoured so far, because of their speedy action and ease of application. Although, the economic benefits of pesticides are well recognized, a major drawback with the use of chemical insecticides is that they are non-selective and could be harmful to other beneficial organisms, environmental pollution and rising costs. Moreover, many vectors have developed resistance to widely used pesticide. This causes the problem of vector resurgence in many epidemic and endemic zones (Das et al., 1991; Kalyanasundaram and Babu, 1982). widely used pesticide. This causes the problem of vector resurgence in many epidemic and endemic zones (Das et al., 1991; Kalyanasundaram and Babu, 1982). The pesticides carried through food chain affect the non target organisms. Some of the insecticides are carcinogenic agents and are positively dangerous (Pingale, 1976). Many of these pesticides are known to persist for long period of time and this in turn affects the physiological status of beneficial organisms (Rao and Rao, 1976). Recently the workers have shifted their focus from synthetic insecticides to botanicals because the plant materials are nontoxic to non-target animals, have no phytotoxic properties and leave no residues in the environment. The plants and their products could be used in the control of insects, offering a safer alternative to conventional pesticides use (Mani, 1982). In recent times, sustained efforts have been made to reduce the population of insect vectors, particularly mosquitoes, by using biological means, which have considerable advantages over chemical pesticides (Rajamohan et al., 1987). The phytochemicals may be secondary metabolites and are divided into two major groups based on their solubility.Carbohydrates, aminoacid, nucleic acid bases, organic acids and phenolic compounds are polar or water soluble constituents and are extracted with alcohol and ethyl acetate where as lipids, steroids, carotenoid, simple quinone and chlorophylls are non polar or lipid soluble constituents and are extracted with petroleum ether or chloroform. Using a single