Larvicidal, ovicidal and oviposition deterrent efficacy of extracts of two plant species against culex quinquefasciatus say, at Mysuru, India

Background: Mosquito control has been facing problem mainly because of the development of resistance to chemical insecticides. Hence research on plant-based bioactive insecticides as parts of integrated vector management have received renewed attention. In this regard the present study was undertaken to assess the larvicidal, ovicidal and oviposition deterrent activity of different solvent extracts of Dalbergia oliveri leaves and Heracleum rigens seeds against Culex quinquefasciatus, the Filariasis vector in India. Material and methods: The larvicidal bioassay was conducted following the WHO method, Ovicidal and Oviposition deterrent activity tests were carried out following the method of Rajkumar and Jebanesan, (2009). Results: Results indicate that maximum larvicidal activity was found with the petroleum ether extract of both D. oliveri and H. rigens against the vector species with LC50 values being 36.28ppm and 69.25ppm respectively. In the ovicidal activity assay, the petroleum ether extract of D. oliveri and H. rigens produced 100% mortality at 100 ppm and 125ppm against Cx. quinquefasciatus eggs. Here the LC50 value for D. oliveri was 24.98ppm compared to 34.83ppm for H. rigens. Likewise in oviposition deterrent effect experiment, petroleum ether extract of both D. oliveri and H. rigens exhibited 100% activity at 50ppm and 125ppm with LC50 value 14.62ppm and 39.03ppm respectively. Conclusion: These investigations indicate that the leaf/seed extracts of local plants have the potential to be developed eco-friendly phyto molecules for vector control. Further, the results also pinpoint the superior efficacy of D. oliveri.