Evaluation of larvicidal activity of the leaf extract of a weed plant, Ageratina adenophora , against two important species of mosquitoes, Aedes aegypti and Culex quinquefasciatus

African Journal of Biotechnology (ISSN: 1684-5315) Vol 6 Num 5
Source: OAI

ABSTRACT An attempt is made in the present study to analyse the larvicidal effect of the leaf extract of a vastly grown (in the hilly regions of the Nilgiris district) weed plant, Ageratina adenophora on two important mosquito species, Aedes aegypti and Culex quinquefasciatus. The larval mortality of fourth instar larvae of A. aegypti and C. quinquefasciatus after 24 h of treatment were observed separately in control, 50, 100, 150, 200, 250, 300, 350, 400, 450 and 500 ppm concentrations of the leaf extract (acetone) of κA. adenophora. Based on the Probit analysis, the 24 h Lc50 value of the leaf extract of A. adenophora was found to be 356.70 ppm for A. aegypti and 227.20 ppm for C. quinquefasciatus. When compared to neem, the leaf extract of A. adenophora is more toxic to both A. aegypti and C. quin-quefasciatus and could be effectively used for the control of mosquito larvae.

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    ABSTRACT: BACKGROUND: Integrated Vector Control (IVC) remains the approach for managing the malaria-causing vector. The study investigated the contribution of Bacillus thuringiensis israelensis (Bti) in the control of malaria by targeting the larvae and also mapped and documented major breeding sites in the Kumasi metropolis, Ghana. METHODS: Using a hand held GPS receiver unit, major breeding sites within the metropolis were mapped out during the larval survey. Mosquito larvae were then collected from the breeding sites and reared in an insectary to obtain an F1 generation for laboratory bioassays. The minimum effective dosage of Bti Water Dispersible Granular (WDG) formulation was determined by a series of bioassays. Based on the results obtained in the laboratory, the optimum effective dosage of Bti formulations against naturally occurring larvae of the indigenous mosquito species was determined through open field trials. RESULTS: A total of 33 breeding sites were identified and geo-referenced during the larval surveys with the majority of the breeding sites located in the Asokwa sub-metropolis, Kumasi, Ghana. A Bti (3,000 International Toxic Unit (ITU)/mg) concentration of 0.026 mg/l resulted in 50% mortality whilst a concentration of 0.136 mg/l resulted in 95% mortality. Results from the open field trials with Bti showed that a dosage of 0.2 kg/ha is as effective as 0.4 kg/ha in suppressing late instars and resulting pupae. CONCLUSION: This study reveals that Bti at a very low dosage of 0.2 kg/ha is highly effective against Anopheles larvae and therefore offers viable options for the management of vector mosquitoes. Further research is needed to extend this to the field in order to determine its ability to reduce malaria incidence.
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    ABSTRACT: The larvicidal, behavioral, and morphological response of dengue vector, Aedes aegypti treated with deleterious weed, Argemone mexicana, was explored. The 1,000 ppm extracts of A. mexicana leaf, stem, and roots prepared in five different solvents (petroleum ether, hexane, benzene, acetone, and ethanol) were screened for their larvicidal activity against dengue vector establishing the efficacy of petroleum ether and hexane extracts. Other extracts, unable to give 100 % mortality, were considered ineffective and discarded from further study. Larvicidal bioassay conducted with selected extracts confirmed the higher efficacy of hexane extracts exhibiting 1.1- to 1.8-fold more potential than the petroleum ether extracts. The results further revealed 1.6- to 2.4-fold higher efficacy of root extracts than those prepared from the leaves and stem of A. mexicana. The hexane root extract of A. mexicana was found to be the most effective larvicide with LC50 value of 91.331 ppm after 24 h of exposure causing 1.8 and 2.4 fold more toxicity as compared to the hexane leaf and stem extracts, respectively. Prolonged exposure of the larvae to the extracts resulted in increased toxicity potential of the extracts. Observations of the treated larvae revealed excitation, violent vertical, and horizontal movements with aggressive anal biting behavior suggesting effect of extracts on their neuromuscular system. Morphological studies of the treated larvae revealed the demelanization of cuticle and shrinkage of internal cuticle of anal papillae indicating the anal papillae as the probable action sites of the A. mexicana extracts. The potential of A. mexicana as new larvicides against dengue vector are being explored.
    Parasitology Research 07/2013; · 2.85 Impact Factor
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    ABSTRACT: Larvicidal activity of crude petroleum ether (PE), ethyl acetate (EtOAc) and methanol (MeOH) extracts of leaves and stem barks of Sterculiaquinqueloba (Garcke) K. Schum were testedagainst the late 3rd instar larvae of Anopheles gambiae, Aedesaegypti and Culexquinquefasciatusat 5 different concentrations50 – 800μg/ml. The larval mortality was observed after 24h, 48h and 72h of exposure. At 24h of exposure all extracts showed moderate larvicidal effects, except for methanolic extracts which showed very week effect at LC50>750μg/ml.The highest larvicidal activityrecorded for leaf extracts against each species used were LC5027.61μg/ml(EtOAc extracts), LC50 43.9μg/ml(PE extracts) and LC50 68.2μg/ml(EtOAc extracts) for A. gambiae, C. quinquefasciatus and A. aegypti respectively. Only EtOAc extract of stem against A. gambiae gave LC50range between 50 - 100μg/ml. Generally leaf extracts showed higher activity than stem extract. This is an ideal eco-friendly approach aid for the control of mosquito species A. gambiae, A. aegypti and C. quinquefasciatus.
    American Journal of Research Communication. 07/2014; 2(8):61-71.


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