Efficacy of Ruta graveolens extract and its synergistic effect with cypermethrin against Anopheles stephensi Liston larvae

Abstract

Vector-borne diseases constitute 17% of the global burden of infectious diseases. Among them, malaria, with 247 million cases and one million deaths in 109 countries, stands first. Plant extracts can be used as an alternative to synthetic insecticides. This will minimize environmental hazards and vector resistance rate. In one such bioassay at Mysore, India, on Anopheles stephensi an urban malarial vector, extracts of Rue (Ruta graveolens) plant leaves, alone and with cypermethrin, produced promising larvicidal results. Petroleum ether extract with LC₅₀ of 43.5 ppm and LC₉₀ of 90.6 ppm was found to be the best. The co-toxicity coefficient and synergistic factor for the 1 : 1 mixture were 119.4 and 9.94, respectively, for the LC₅₀ at 24th hour. Mixtures of phytochemicals and insecticides were found to be more effective than insecticides or phytochemicals alone and could be a good ecofriendly approach to reduce the dose of chemicals to be applied in vector control programs. Besides, such mixtures could reduce the costs, prolong lifetime of available insecticides, and regulate insecticide resistance as part of integrated vector management.

Keywords:

• phytoextracts
• Ruta graveolens
• Anopheles stephensi
• larvicidal activity
• synergism

Acknowledgments

The authors are grateful to the Chairman, DOS in Zoology, University of Mysore, for providing necessary facilities. We also thank Tagros Chemicals India Ltd for kindly providing us with cypermethrin of technical grade. A.A. Aivazi is thankful to Ilam Medical Sciences University, Iran, for financial support.