Arthropod borne diseases constitute a major health problem in India. Among the arthropod vectors, mosquitoes are important as they are responsible for diseases like Malaria, Filaria, Yellow fever, Dengue, Chickungunya etc. In India of all vector borne diseases, Malaria and Filaria cause most concern to public health [1,2]. The use of chemicals hazardous to human and wild life has not only developed resistance in insects, but also in the outbreak of pests. These factors have evoked considerable interest in the adoption of biological control in recent years [3]. Eradicating mosquitoes in larval stages is more effective than that of adults. In the absence of vaccine, vector control is the only practical approach. Larvicidal activity of more than hundreds of plant species have been tested against mosquito vectors [4,5,6,7,8]. Bacillus sphaericus, a mosquito control agent, originates from the presence of binary toxin composed of two proteins that work together to lyse gut cells of susceptible larvae [9]. Oceans have a rich wealth of bioactive compounds secreted by animals as chemical defence. Ascidians commonly called ‘sea squirts’ are an interesting group of marine, sedentary organisms found to occur in abundance in Tuticorin coast. They are considered as a nuisance as they grow on all underwater marine structures and are usually thrown away. Such discards may have a wealth of natural products. Hence in the search for a new compound with larvicidal activity, ascidians may prove to be a timely alternative. In the present study, two species of ascidians collected from Tuticorin coast has been screened for larvicidal properties against the larvae of Anopheles stephensi and Culex quinquefasciatus.
