title: Efficacy of indigenous plant extracts on the malaria vector Anopheles subpictus Grassi (Diptera: Culicidae).
abstract: OBJECTIVE
  Mosquito control is facing a threat due to the emergence of resistance to synthetic insecticides. Insecticides of plant origin may serve as suitable alternative biocontrol techniques in the future. The purpose of the present study was to assess the ethyl acetate, acetone and methanol extracts of Andrographis paniculata, Eclipta prostrata and Tagetes erecta leaves tested for oviposition-deterrent, ovicidal and repellent activities against malaria vector, Anopheles subpictus Grassi (Diptera: Culicidae).
  
  
  METHODS
  The dried leaves of the three plants were powdered mechanically and extracted with ethyl acetate, acetone and methanol. One gram of crude extract was first dissolved in 100 ml of acetone (stock solution). From the stock solution, test solution concentrations of 31.21- 499.42 mg/l for oviposition- deterrence assay and repellency and 15.60 - 998.85 mg/l were used in ovicidal assay. The percentage oviposition- deterrence, hatching rate of eggs and protection time were calculated. One-way analysis of variance was used for the multiple concentration tests and for per cent mortality to determine significant treatment differences.
  
  
  RESULTS
  The percentage of effective oviposition repellency was highest at 499.42 mg/l and the lowest at 31.21 mg/l in ethyl acetate, acetone and methanol extracts of A. paniculata, E. prostrata and T. erecta. The oviposition activity index (OAI) value of ethyl acetate, acetone and methanol extracts of A. paniculata, E. prostrata and T. erecta at 499.42 mg/l were -0.91, -0.93, -0.84, -0.84, -0.87, -0.82, -0.87, -0.89 and -0.87, respectively. Mortality (no egg hatchability) was 100 per cent with ethyl acetate and methanol extracts of A. paniculata, E. prostrata and T. erecta at 998.85 mg/l. The maximum adult repellent activity was observed at 499.42 mg/l in ethyl acetate extracts of A. paniculata, E. prostrata and methanol extracts of T. erecta, and the mean complete protection time ranged from 120 to 150 min with the different extracts tested.
  
  
  CONCLUSIONS
  The acetone extract of A. paniculata, methanol extract of E. prostrata and T. erecta showed good oviposition-deterrent, ovicidal and repellent activities respectively. These results suggest that the leaf extracts of A. paniculata, E. prostrata and T. erecta may have the potential to be used as an ideal eco-friendly approach for the control of the An. subpictus.
authors: Post Graduate & Research Department of Zoology, C. Abdul Hakeem College, Melvisharam, Vellore District, Tamil Nadu, India.
authors: G
authors: G
authors: Elango
authors: A Abduz
authors: AA
authors: Zahir
authors: A
authors: A
authors: Bagavan
authors: C
authors: C
authors: Kamaraj
authors: G
authors: G
authors: Rajakumar
authors: T
authors: T
authors: Santhoshkumar
authors: S
authors: S
authors: Marimuthu
authors: A Abdul
authors: AA
authors: Rahuman
mesh_terms: D000085:Acetates; D000096:Acetone; D000704:Analysis of Variance; D035685:Andrographis / Q000737:chemistry*; D000818:Animals; D000852:Anopheles / Q000187:drug effects*; D036601:Eclipta / Q000737:chemistry*; D007194:India; D007303:Insect Vectors / Q000187:drug effects*; D000432:Methanol; D009032:Mosquito Control / Q000379:methods*; D010058:Oviposition / Q000187:drug effects; D010063:Ovum / Q000187:drug effects; D010936:Plant Extracts / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry*; D031686:Tagetes / Q000737:chemistry*
chemical_list: D000085:Acetates; D010936:Plant Extracts; D000096:Acetone; C007650:ethyl acetate; D000432:Methanol