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Journal Of Tropical Biosciences

Year: 2015|   Volume No: 10|   ISSN: 0795-3089|   Page No: 


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Title:  EFFECTS OF AQUEOUS AND METHANOLIC LEAF EXTRACTS OF AGERATUM CONYZOIDES L. AND GUIERA SENEGALENSIS L. AGAINST MOSQUITO LARVAE IN ZARIA

MUSA, A.O., SOW, G.J., NASIR, I. F., SHUAIBU, B.U. AND EDOGBANYA, P.R.O.

DEPARTMENT OF BIOLOGICAL SCIENCES, AHMADU BELLO UNIVERSITY, ZARIA

ABSTRACT

Methanol and aqueous leaf extracts of Ageratum conyzoides and Guiera senegalensis were tested against the larvae of Culex quinquefasciatus, Anopheles gambiaes.l. and Aedes aeygpti in Zaria. Different concentrations of 50, 100, 200, and 400 ppm were prepared for the two crude extracts. Percentage mortalities after 24 hrs post treatment across the various concentrations ranged from 45 to 100% with higher concentrations yielding higher mortalities. Mortalities differ significantly between species (P<0.05) at 200 ppm in aqueous extract of A. conyzoides but did not differ significantly (P>0.05) across all concentrations in methanol extract. Similarly, at 100 ppm of methanol extract of G. senegalensis, Cx quinquefasciatus had the highest mortality but there was no significant difference in the aqueous extract across all concentrations. Median lethal concentrations (LC50) ranged between 42.53 ppm and 112.49 ppm recorded in aqueous extract of G. senegalensis against Cx quinquefasciatus and aqueous extract of A. conyzoides against Ae. aegypti respectively. Our data suggest that the aqueous and methanol leaf extract of A. Conyzoides and G. Senegalensis have the potential to be used as eco-friendly approach for the control of mosquitoes.

SUMMARY:

Data generated from the bioassays suggest potency of both methanolic and aqueous extract of Ageratum conyzoides and Guiera senegalensis against the larvae of Cx. quinquefasciatus, Ae. saegypti and An. Gambiae s.l. The efficacy of phytochemicals against mosquito larvae may vary significantly depending on plant species, plant parts used, solvent used during extraction as well as vector used for bioassay (Sukumar et al., 1991). It has been shown that the extraction of active biochemical from plants depends upon the polarity of the solvents used. Polar solvent will extract polar molecules and non-polar solvents extract non-polar molecules.It has been found that in most of the studies, solvent with minimum polarity have been used such as hexane, methanol, petroleum ether or that with maximum polarity such as aqueous/steam distillation. However, those bio-chemicals that were extracted using moderately polar solvents were also seen to give good results. Thus, different solvent types can significantly affect the potency of extracted plant compounds and there is difference in the chemo-profile of the plant species. Median lethal concentration (LC50) values obtained in this study (ranging between 42.53 and 112.49 ppm) compares favourably with other works done elsewhere. For instance, 53.60 ppm was reported from Solenostemmaargel against Cx. pipiens and Several other plants such as, Atlantia monophylla (20.26ppm)and Centella asiatic (50.67ppm) (Ghosh and Chandra,2006). Higher values of LC50 were obtained from Leaf of Solanum nigrum (107.01) and Azadirachta indica (560.32 ppm) (Mgbemena, 2010). The plants, A. conyzoides and G. senegalensis are excellent candidates of choice to be used as bio-friendly pesticides for their abundance especially period mestically. In addition G. senegalensis is a perennial shrub that is resistant to drought.

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