Journal of Environmental Biology

Comparative larvicidal potential of different plant parts of Withania somnifera

against vector mosquitoes in the semi-arid region of Rajasthan

Author Details

S.K. Bansal

(Corresponding author)

Desert Medicine Research Centre (ICMR), New Pali Road, Jodhpur - 342 005, India

e-mail: bansalsk@dmrcjodhpur.org

Karam V. Singh

Desert Medicine Research Centre (ICMR), New Pali Road, Jodhpur - 342 005, India

Sapna Sharma

Desert Medicine Research Centre (ICMR), New Pali Road, Jodhpur - 342 005, India

M.R.K. Sherwani

Department of Chemistry, JNV University, Jodhpur - 342 005, India

Publication Data

Paper received:

07 April 2010

Revised received:

20 July 2010

Accepted:

30 July 2010

Abstract

Larvicidal potential of the extracts from different parts viz. green and red fruits, seeds, fruit without seeds, leaves and roots of Withania somnifera in different solvents was evaluated against larvae of Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus, the important disease vectors prevalent in the semi-arid region.? Experiments were carried out on late 3^rd or early 4^th instar larvae of these mosquitoes using standard WHO technique. 24 and 48 hr LC₅₀ values along with their 95% confidence limits, regression equation, chi-square (c2)/ heterogeneity of the response have been determined by log probit regression analysis. The 24 hr LC₅₀ values as observed for whole green fruits in water, methanol and petroleum ether were 350.9, 372.4, 576.9; 115.0, 197.1, 554.6; 154.9, 312.0, 1085.0 while corresponding values for red fruits were 473.5, 406.4, 445.2; 94.7, 94.5, 1013.0; 241.8, 535.0, 893.3 mg l^-1 for An. stephensi, Ae. aegypti and Cx. quinquefasciatus respectively showing that methanol extracts were more effective against anophelines as compared to culicines when whole fruits were taken. The 24 hr LC₅₀ values as observed for seeds in acetone, methanol and petroleum ether were 188.1, 777.5, 822.5; 245.5, 769.0, 1169.0; 140.3, 822.9, 778.4 and for fruit without seeds were 80.2, 97.6, 146.6; 88.4, 404.4, 1030.0; 30.0, 44.5, 54.2 mg l^-1 for the above mosquito species respectively showing that extract of fruit without seeds were most effective in petroleum ether followed by acetone and methanol extracts. However, experiments conducted with methanol extracts of leaves and roots of this plant species did not show any appreciable larvicidal activity and a 20-40% mortality was observed up to 500 mg l^-1 of the extracts. Overall larvae of anophelines were found more susceptible as compared to culicines to all the extracts tested. Petroleum ether extract of fruit without seeds was found most effective against all the mosquito species showing that active ingredient might be present in this part of the plant species. The study would be of great importance while planning vector control strategy based on alternative plant derived insecticides.

Key words

Larvicidal potential, Withania somnifera, Mosquito, Semi-arid region, Vector control

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