Insecticidal And Residual Properties Of Ipomoea Cairica Linn Extracts Against Culex Quinquefasciatus Say (Diptera : Culicidae)
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Date
2014-02
Authors
Maniam, Thigaletchumi
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Publisher
Universiti Sains Malaysia
Abstract
In recent years, the use of substances from plant origin as alternative to synthetic insecticide in mosquito control had gained much interest. This research focuses on the larvicidal and residual activity of Ipomoea cairica extracts against wild strain of Culex quinquefasciatus and its’ interference in oviposition site selection by the mosquito. Different parts of Ip. cairica which include; leaves, stem and flower buds were ground and extracted with acetone or methanol by using two different methods; maceration and Soxhlet. Acethonilic extract of Ip. cairica leaves showed an effective larvicidal activity against Cx. quinquefasciatus larvae with significantly lower LC50 value of 110.65ppm. The highest percentage of yield extract with better larvicidal efficacy was obtained by Soxhlet with acetone as solvent for all the different plant parts. Maceration only provided 1/3 of yield compared to the Soxhlet technique. Residual properties of acethonilic extract of Ip. cairica leaves were evaluated based on two test regime; replenishment of water and without replenishment of water. Trials were terminated when the mortality rate falls below 50%. Mortality rate were significantly reduced after 28 days in test jars without replenishment of water, and for test jars with replenishment of water mortality rate declined significantly after 21 days (P < 0.05). There were no adult emergence observed from the exposed larvae that survived in test jars without replenishment of water up to day 7 of post treatment and day 2 of post treatment with replenishment of water. Two different sets of oviposition choice experiments were conducted; (1) Single solution offered in a cage, and (2) multiple concentration solutions in one cage. Gravid female mosquito was found to be attracted to the oviposition site with
high intensity and darker color of the acethonilic extract of Ip. cairica leaves. However, the gravid female was subsequently drowned thus inhibiting oviposition activity in both tests. More gravid females were found drowned at the highest concentration, 300ppm of acethonilic extract of Ip. cairica leaves.
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Keywords
Substances from plant origin , synthetic insecticide