title: Screening of selected ethnomedicinal plants from South Africa for larvicidal activity against the mosquito Anopheles arabiensis.
abstract: BACKGROUND
  This study was initiated to establish whether any South African ethnomedicinal plants (indigenous or exotic), that have been reported to be used traditionally to repel or kill mosquitoes, exhibit effective mosquito larvicidal properties.
  
  
  METHODS
  Extracts of a selection of plant taxa sourced in South Africa were tested for larvicidal properties in an applicable assay. Thirty 3rd instar Anopheles arabiensis larvae were exposed to various extract types (dichloromethane, dichloromethane/methanol) (1:1), methanol and purified water) of each species investigated. Mortality was evaluated relative to the positive control Temephos (Mostop; Agrivo), an effective emulsifiable concentrate larvicide.
  
  
  RESULTS
  Preliminary screening of crude extracts revealed substantial variation in toxicity with 24 of the 381 samples displaying 100% larval mortality within the seven day exposure period. Four of the high activity plants were selected and subjected to bioassay guided fractionation. The results of the testing of the fractions generated identified one fraction of the plant, Toddalia asiatica as being very potent against the An. arabiensis larvae.
  
  
  CONCLUSIONS
  The present study has successfully identified a plant with superior larvicidal activity at both the crude and semi pure fractions generated through bio-assay guided fractionation. These results have initiated further research into isolating the active compound and developing a malaria vector control tool.
authors.affiliation: South African Medical Research Council, 491 Ridge Road, Overport, Durban 4001, South Africa. rmaharaj@mrc.ac.za
authors.forename: Rajendra
authors.initials: R
authors.lastname: Maharaj
authors.forename: Vinesh
authors.initials: V
authors.lastname: Maharaj
authors.forename: Neil R
authors.initials: NR
authors.lastname: Crouch
authors.forename: Niresh
authors.initials: N
authors.lastname: Bhagwandin
authors.forename: Peter I
authors.initials: PI
authors.lastname: Folb
authors.forename: Pamisha
authors.initials: P
authors.lastname: Pillay
authors.forename: Reshma
authors.initials: R
authors.lastname: Gayaram
mesh_terms: D000818:Animals; D000852:Anopheles / Q000187:drug effects*; D004353:Drug Evaluation, Preclinical / Q000379:methods; D006801:Humans; D007306:Insecticides / Q000302:isolation & purification* / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects; D010936:Plant Extracts / Q000302:isolation & purification* / Q000494:pharmacology*; D010946:Plants, Medicinal / Q000737:chemistry*; D027821:Rutaceae / Q000737:chemistry*; D013019:South Africa; D016019:Survival Analysis
chemical_list: D007306:Insecticides; D010936:Plant Extracts