title: Mosquitocidal and water purification properties of Cynodon dactylon, Aloe vera, Hemidesmus indicus and Coleus amboinicus leaf extracts against the mosquito vectors.
abstract: Ethanolic extracts of Cynodon dactylon, Aloe vera, Hemidesmus indicus and Coleus amboinicus were tested for their toxicity effect on the third-instar larvae of Anopheles stephensi, Culex quinquefasciatus and Aedes aegypti. The leaves of C. dactylon, A. vera, H. indicus and C. amboinicus were collected from natural habitats (forests) in Western Ghats, Tamil Nadu, India. A total of 250 g of fresh, mature leaves were rinsed with distilled water and dried in shade. The dried leaves were put in Soxhlet apparatus and extract prepared using 100% ethanol for 72 h at 30-40°C. Dried residues were obtained from 100 g of extract evaporated to dryness in rotary vacuum evaporator. Larvicidal properties of ethanolic leaf extracts showed that the extracts are effective as mosquito control agents. The larval mortality was observed after 24 h exposure. No mortality was observed in the control. The median lethal concentration (LC(50)) values observed for the larvicidal activities are 0.44%, 0.51%, 0.59% and 0.68% for extracts of C. dactylon, A. vera, H. indicus and C. amboinicus, respectively. The observed mortality were statistically significant at P < 0.05 level. C. dactylon showed the highest mortality rate against the three species of mosquito larvae in laboratory and field. The selected plants were shown to exhibit water purification properties. Water quality parameters such as turbidity, pH and water clarity were analyzed in the water samples (pre-treatment and post-treatment of plant extracts) taken from the different breeding sites of mosquitoes. Water colour, turbidity and pH were reduced significantly after treatment with C. dactylon (13 HU, 31.5 mg/l and 6.9), H. indicus (13.8 HU, 33 mg/l and 7.1), A. vera (16 HU, 33.8 mg/l and 7.4) and C. amboinicus (21 HU, 35 mg/l and 7.5) extracts. The study proved that the extracts of C. dactylon, A. vera, H. indicus and C. amboinicus have both mosquitocidal and water sedimentation properties.
authors.affiliation: Division of Entomology, Department of Zoology, School of Life Sciences, Bharathiar University, Coimbatore, 641046 Tamil Nadu, India. naresharjun06@yahoo.co.in
authors.forename: Nareshkumar
authors.initials: N
authors.lastname: Arjunan
authors.forename: Kadarkarai
authors.initials: K
authors.lastname: Murugan
authors.forename: Pari
authors.initials: P
authors.lastname: Madhiyazhagan
authors.forename: Kalimuthu
authors.initials: K
authors.lastname: Kovendan
authors.forename: Kanagarajan
authors.initials: K
authors.lastname: Prasannakumar
authors.forename: Sundaram
authors.initials: S
authors.lastname: Thangamani
authors.forename: Donald R
authors.initials: DR
authors.lastname: Barnard
mesh_terms: D000330:Aedes / Q000187:drug effects; D000504:Aloe / Q000737:chemistry*; D000818:Animals; D000852:Anopheles / Q000187:drug effects; D031330:Coleus / Q000737:chemistry*; D003465:Culex / Q000187:drug effects; D031744:Cynodon / Q000737:chemistry*; D031102:Hemidesmus / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007194:India; D007306:Insecticides / Q000032:analysis / Q000737:chemistry*; D007814:Larva / Q000187:drug effects; D007928:Lethal Dose 50; D009032:Mosquito Control / Q000379:methods; D010936:Plant Extracts / Q000032:analysis / Q000737:chemistry*; D018515:Plant Leaves / Q000737:chemistry; D018508:Water Purification / Q000379:methods*; D060753:Water Quality
chemical_list: D007306:Insecticides; D010936:Plant Extracts