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Effects of Different Foliar Extracts of Neem (azadirachta Indica A. Juss) on the Larvae of Culex Quinquefasciatus Say (diptera: Culicidae)

M. ISMAIL HOSSAIN
Department of Zoology, University of Dhaka, Dhaka-1000, Bangladesh

G.M. SAIFUR RAHMAN
Department of Zoology, University of Dhaka, Dhaka-1000, Bangladesh

MAHMUD-UL AMEEN
Department of Zoology, University of Dhaka, Dhaka-1000, Bangladesh

SK. NAZRUL ISLAM
Institute of Nutrition and Food Science, University of Dhaka, Dhaka-1000, Bangladesh.

Abstract/ Executive Summary:

The efficacy of various extracts (water, ethanol, chloroform and petroleum ether) from different foliar parts (green leaf, fallen leaf and petiole ) of neem, Azadirachta indica A. Juss, were tested at room temperature in the laboratory against the 3rd and 4th instar larvae of Culex quinquefasciatus Say. The LC₅₀ values of the different foliar extracts were in the following order of toxicity: hot petroleum ether extract of petiole (0.006 ppt) > hot petroleum ether extract of green leaf (0.025 ppt) > hot petroleum ether extract of fallen leaf (0.06 ppt ) > hot chloroform extract of green leaf ( 0.09 ppt > hot chloroform extract of fallen leaf (0.16 ppt) > cold chloroform or petroleum ether extract of petiole (0.28 ppt) > cold ethanol extract of green leaf (0 .80 ppt) > hot ethanol extract of fallen leaf (3.65 ppt) > cold petroleum ether extract of fallen leaf ( 2.84 ppt) > cold chloroform extract of green leaf (3.56 ppt) > cold ethanol extract of fallen leaf (3.61 ppt) > water extract of fallen leaf (30.45 ppt) > water extract of petiole (54.9 ppt). Hot extracts were always more toxic than the cold extracts. In general petiole extracts w ere better than leaf extract; green extracts were better than fallen leaf extracts. Among the solvents petroleum ether showed the best performance followed by chloroform, ethanol and water.

Keywords: Neem, Azad irachta indica, Foliar extract, Mosquito larvae, Culex quinquefasciatus

Location: Department of Zoology, University of Dhaka

Start Date:

End Date:

Program Area: Pest Management

Non-commodity: Performance

Objectives:

To investigates the larvicidal action of the extracts from different foliar parts of neem against larval Cx. quinquefasciatus mosquito of Dhaka city.

Methodology:

Experiments were conducted at room temperature in the laboratory of the Department of Zoology, University of Dhaka using late 3rd or early 4th instar larvae of Cx. quinquefa sciatus . Extracts were obtained from green and fallen leaves as well as leaf petioles both in hot and cold conditions using petroleum ether, chloroform and ethanol as solvents. Cold water extracts were also tested. Measured quantities of the extracts were taken in properly labeled reagent bottles. Polyethylene glycol 400 in water was added for enhancing miscibility. The mixture was shaken thoroughly. At the beginning a 10% solution was prepared. The solution was further diluted by adding requisite amount of water to make a 1% solution, which was used as the stock solution. The stock solution was stored in a refrigerator in a tightly stoppered container. Required amount of this stock solution was taken in a glass beaker and water was added to have the desired concentration. Cx. quinquefasciatus mosquito was colonized in the laboratory at room temperature ( 25 ± 5°C) and at 75 ± 10 % relative humidity following Ameen and Moizuddin for a regular supply of larvae. Batches of 25 larvae were exposed to the test solutions in 250 ml glass beakers for 24 hours. Preliminary screening tests were performed to determine the lowest and the highest doses that would give zero and 100% mortality of the larvae. Then a series of 4 to 7 concentrations were chosen which gave mortality below and above 50 %. The test concentrations were prepared by pipeiting the appropriate volume of the extract solution to water in the beakers. Each test consisted of five replications and a control having no extract. Food was not provided to the larvae during the tests. Mortality was counted at the end of 24 hours exposure period. The moribund larvae were not considered to be dead. There was control mortality in only one test.

Source of Information: Dhaka Univ. J. Biol. Sci. 10(2): 121-127, 2001 (July)

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

The present observation indicates the potential of neem foliar extracts as a controlling agent against mosquito larvae. For better results and easy handling it is necessary to isolate active toxic compounds and prepare potent formulations.

Knowledge Management: Journal