Indian Journal of Medical Research

ORIGINAL ARTICLE
Year
: 2012  |  Volume : 135  |  Issue : 3  |  Page : 397--400

Evaluation of toxicity of plant extracts against vector of lymphatic filariasis, Culex quinquefasciatus


M Sakthivadivel1, Alex Eapen1, AP Dash2,  
1 National Institute of Malaria Research (ICMR), IDVC Field Unit, Chennai, India
2 World Health Organization, Regional Office for South-East Asia, New Delhi, India

Correspondence Address:
M Sakthivadivel
National Institute of Malaria Research (ICMR), IDVC Field Unit, Ayapakkam, Chennai 600 077
India

Abstract

Background & objectives: Conventional insecticides are generally used as larvicides to control Culex quinquefasciatus, vector of lymphatic filariasis. This study was undertaken to evaluate the larvicidal activity of some potential larvicidal plants leaf extracts against Cx. quinquefasciatus larvae. Methods: The toxic effects of petroleum ether leaf extracts of plants viz., Argemone mexicana (Mexican prickly poppy), Clausena dentata (Dentate), Cipadessa baccifera (Rana bili), Dodonaea angustifolia (Hop bush) and Melia dubia (Pride of India) were evaluated under laboratory conditions in individual and in combination against 3 rd - 4 th instar larvae of Cx. quinquefasciatus. Results: The results indicated that among the selected plants, A. mexicana showed maximum larvicidal activity with an LC 50 value of 48.89 ppm. Its toxicity was enhanced when the extract was mixed (1:1) with that of C. dentata as the LC 50 value became 28.60 ppm indicating synergistic action of A. mexicana. Interpretation & Conclusions: Our results showed high larvicidal potential in A. mexicana leaf extract, and it also showed additive effect when mixed with C. dentata extract.



How to cite this article:
Sakthivadivel M, Eapen A, Dash A P. Evaluation of toxicity of plant extracts against vector of lymphatic filariasis, Culex quinquefasciatus.Indian J Med Res 2012;135:397-400


How to cite this URL:
Sakthivadivel M, Eapen A, Dash A P. Evaluation of toxicity of plant extracts against vector of lymphatic filariasis, Culex quinquefasciatus. Indian J Med Res [serial online] 2012 [cited 2019 Nov 20 ];135:397-400
Available from: http://www.ijmr.org.in/text.asp?2012/135/3/397/95627


Full Text

The tropicopolitan mosquito, Culex quinquefasciatus is the vector of lymphatic filariasis in India. Filariasis is a major public health problem and globally 120 million people are at risk [1] . In India, one-third of the people are afflicted with 40 per cent of the global burden of the disease [2] . Mass drug administration (MDA) is now accepted as a global programme to eliminate lymphatic filariasis. There is a general consensus that the time for elimination can be drastically reduced if MDA is coupled with appropriate vector control measures. At present, control of Cx. quinquefasciatus is practiced using conventional insecticide as larvicides. This approach has been confronted with twin problems of vector resistance to insecticides and environmental hazards likely to be caused by insecticides. It is considered that many plant based compounds have potential larvicidal activity and this would be used as alternative larvicides as these are effective, ecofriendly and minimize the development of resistance in mosquitoes [3] . Since, India has a rich plant diversity, attempts are in progress to find potential larvicidal plants. The objective of the present study was to evaluate extracts of a few promising plants against larvae of Cx. quinquefasciatus.

 Material & Methods



The study was conducted at MS Swaminathan Research Foundation and National Institute of Malaria Research - Field Unit, Chennai during the period of August 2007 to March 2009.

The leaves of five species of plants viz., Argemone mexicana (Mexican prickly poppy), Clausena dentata (Dentate), Cipadessa baccifera (Rana bili), Dodonaea angustifolia (Hop bush) and Melia dubia (Pride of India) were collected from different geographical locations of Tamil Nadu. The leaves of each plant were washed thoroughly with water and shade dried. The dried leaves were powdered separately with an electric blender and Soxhlet extracted with petroleum ether cycles for 36 h and subsequently the extract was concentrated and dried using flask evaporates [3],[4] .

A stock emulsified water solution of the extract of 1000 ppm was prepared using 250 mg of the extract in a flask dissolved in 4 ml of acetone and 0.1 ml of Tween 20 (emulsifier) and made up to 250 ml using distilled water. This was sequentially diluted with water to obtain 500, 250, 125 and 62.5 ppm of the extract. Before each dilution, the solution was shaken well to ensure uniform distribution of the extract in the emulsion. Stock control solution was prepared using 4 ml of acetone and 1 ml of Tween 20 in 250 ml of water and this was appropriately diluted with water to serve as control for each treatment. Since A. mexicana showed high toxicity to larvae [5] , this plant extract was mixed with other four plant extracts separately in 1:1 proportion to see for synergistic effect in any of the different combinations. Larval susceptibility tests were conducted as per WHO protocol [6] . Susceptibility tests were performed in disposable plastic cups. In each 125 ml of the emulsion of different concentrations were taken separately and in each cup 20 larvae (late 3 rd and early 4 th instar) were introduced. Each treatment had five replicates with appropriate controls. The independent and combined toxicity observations were made on total number of larval mortality, pupal development, pupal mortality and adult emergence with five replicates at every 24 h (24, 48, 72 and 96 h) interval [Table 1] & [Table 2]. Pupae when present were not included for calculation of percentage mortality.{Table 1}{Table 2}

Statistical analysis: Corrected percentage mortality was calculated using Abbott`s formula [7] . From the corrected mortality larval LC 50 and LC 90 values were calculated using the computation programme of Probit analysis [8] .

 Results & Discussion



Larvicidal efficacy of the plant extracts are given in [Table 3]. Among the five plant extracts, C. baccifera and M. dubia were almost non-toxic as 1000 ppm ensured only 12 per cent mortality. Among the other three plant species, A. mexicana showed highest toxicity having an LC 50 and LC 90 values of 48.89 and 463.94 ppm, respectively. D. angustifolia extract showed LC 50 value of 973 ppm and C. dentata 1435 ppm. A. mexicana extract when mixed with C. dentata (1:1 proportion) drastically reduced the LC 50 value to 28.6 ppm. However, similar combination with extracts of C. baccifera, D. angustifolia and M. dubia showed an increase in LC 50 values of A. mexicana indicating absence of any additive effect [Table 3].{Table 3}

The present study revealed that A. mexicana extract had high larvicidal potential among the five plant extracts tested. Further isolation and purification of the toxic principle from the extract can enhance the larval toxicity of A. mexicana. Other plants viz., C. dentata, C. baccifera, D. angustifolia and M. dubia were found to be non-toxic to the mosquito larvae. However, when the A. mexicana extract was mixed with plant extracts of C. dentata and D. angustifolia in 1:1 proportion, a reduction in their LC 50 values was observed. Plant based compounds are known to be ecofriendly and can be used in mosquito larval control ensuring maximum safety in any ecological condition. The present results clearly indicated that A. mexicana leaf extract had high larvicidal potency that can be exploited by further purification of the toxic principles in A. mexicana and identifying the synergistic compound in C. dentata and D. angustifolia.

 Acknowledgment



The first author (MS) acknowledges Council of Scientific & Industrial Research (CSIR), New Delhi for the financial support as Research Associateship.

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