|
Full Length Research Paper
|
|
Aloe
plant extracts as alternative larvicides for mosquito
control
Josphat C.
Matasyoh1*, Euty M. Wathuta2, Samuel
T. Kariuki2, Regina Chepkorir1 and
Judith Kavulani3
1Department
of Chemistry, Egerton University, P. O. Box 536, Egerton
20107, Kenya.
2Department
of Biological Sciences, Egerton University, P. O. Box 536,
Egerton 20107, Kenya.
3Department
of Biochemistry, Egerton University, P. O. Box 536, Egerton
20107, Kenya.
*Corresponding author. E-mail:
josphat2001@yahoo.com.
Tel: 000254-722-871521.
Accepted 18 February, 2008 |
|
|
|
Abstract |
|
|
|
The larvicidal activity of extracts from Aloe turkanensis,
Aloe ngongensis and Aloe fibrosa against the
common malaria vector, Anopheles gambie, was
determined. Ground Aloe leaves from the three plants
were sequentially extracted with hexane, ethyl acetate,
chloroform, acetone and methanol. Only the ethyl acetate
extract of A. turkanensis, hexane, ethyl acetate,
acetone, chloroform and methanol extracts of A.
ngongensis and the hexane, acetone and methanol extracts
of A. fibrosa showed activity. A series of
concentrations of the extracts ranging from 0.05-2 mg/ml
(0.005-0.2% w/v) were tested against third instar larvae and
their percentage mortalities, LC50 values
determined. The ethyl acetate soluble extract of A.
turkanensis showed very high larvicidal activity where
100% mortality was achieved at a concentration of 0.2 mg/ml
and it had an LC50 of 0.11 mg/ml. All the
extracts of A. ngongensis showed larvicidal activity
to A. gambie larvae, but at higher concentration
showing LC50īs of 0.84 (0.55 1.27), 1.14 (0.72
2.28), 0.98 (0.78 1.27), 1.08 (0.90 1.28), 2.0 (1.85
2.36) for the hexane, ethyl acetate, chloroform, acetone and
methanol, respectively. The three active fractions of A.
fibrosa had very close LC50īs ranging from
1.76 1.90 mg/ml. Thin layer chromatographic analysis (TLC)
showed the presence of chromones and anthrones in the
chloroform and ethyl acetate extracts. Application of these
extracts to larval habitats may lead to promising results in
malaria and mosquito management programmes.
Key words:
Aloe, anopheles gambie, larvicidal activity. |
|
