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The Larvicidal Properties of Leaf Extract

Several plants indigenous to many regions are used as natural insecticides, especially for the control of mosquitoes, which carry pathogens causing human diseases. Leaf extracts from many of these plants have been evaluated in laboratory settings and have shown strong larvicidal properties as well as capacities to be used as insect repellents. Development of new, nontoxic and environmentally-safe products is needed to prevent further pollution of soil and water.

  1. Crape Jasmine and Peacock Flower

    • A study appearing in the February 2011 issue of "Parisitology Research" investigated the larvicidal and repellent properties of leaf extracts from Ervatamia coronaria, commonly known as crepe or crape jasmine, and Caesalpinia pulcherrima, also know as the Peacock flower, against three species of mosquitoes, namely Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus. The researchers used both benzene and ethyl acetate extracts from the leaves of the plants and observed the capacity of each to kill the larvae as well as to document the extracts' abilities to deter the insects. The study found that all of the extracts had larvicidal properties, but the most efficient was the benzene extract from E. coronaria against all three species of insects.

    Malabar Nut and Chastetree

    • The August 2010 issue of "Tropical Biomedicine" included a study to investigate the larvicidal activities of various extraction methods of 10 medicinal plants against the larvae of the malaria-carrying mosquito, A. stephensi. The authors followed the suggested guidelines off the World Health Organization to test the compounds with slight modifications. The study found that the highest larvae mortality occurred with an acetone leaf extract of Adhatoda vasica, also known as the Malabar nut, and an ethyl acetate extract from the bark of the same plant. For fourth instar larvae, the authors found a hexane extract from Vitex negundo, more commonly known as the chastetree.

    Puncture Vine

    • An article appearing in the December 2008 issue of "The Journal of Communicable Disease" investigated the effects of acetone extracts of seeds and leaves from Tribulus terrestris, which is also called the puncture vine. The study found that extracts of 200 ppm from the leaf and 100 ppm from the seeds was effective in killing the third instar larvae of four different species of mosquitoes after an exposure time of 24 hours. Additionally, the authors reported that the seed acetone extract showed strong repellent properties against all species of mosquitoes that were tested.

    Red-fruited Nightshade

    • The larvicidal properties of Solanum villosum, also known as the red-fruited nightshade, were investigated in the December 2008 issue of "BMC Complementary and Alternative Medicine." The researchers used an aqueous extract of the leaves of the plant and tested it against three species of mosquitoes in addition to four species of bacteria. The study found that a protein component of the leaf extract has both larvicidal and bactericidal properties. Upon further investigation, the authors concluded that the protein was made up of 15 amino acids including eight that are considered to be "essential."

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