title: Larvicidal and irritant activities of hexane leaf extracts of Citrus sinensis against dengue vector Aedes aegypti L.
abstract: OBJECTIVE
  To assess the larvicidal and irritant activities of the hexane extracts of leaves of Citrus sinensis (C. sinensis) against the early fourth instars and female adults of Aedes aegypti (Ae. aegypti).
  
  
  METHODS
  The larvicidal potential of the prepared leaf extract was evaluated against early fourth instar larvae of Ae. aegypti using WHO protocol. The mortality counts were made after 24 h and LC50 and LC90 values were calculated. The efficacy of extract as mosquito irritant was assessed by contact irritancy assays. Extract-impregnated paper was placed on a glass plate over which a perspex funnel with a hole on the top was kept inverted. Single female adult, 3-day old unfed/blood-fed, was released inside the funnel. After 3 min of acclimatization time, the time taken for the first take-off and total number of flights undertaken during 15 min were scored.
  
  
  RESULTS
  The citrus leaf extracts from hexane possessed moderate larvicidal efficiency against dengue vector. The bioassays resulted in an LC50 and LC90 value of 446.84 and 1 370.96 ppm, respectively after 24 h of exposure. However, the extracts were proved to be remarkable irritant against adults Ae. aegypti, more pronounced effects being observed on blood-fed females than unfed females. The extract-impregnated paper was thus proved to be 7-11 times more irritable as compared with the control paper.
  
  
  CONCLUSIONS
  The hexane extracts from C. sinensis leaves are proved to be reasonably larvicidal but remarkably irritant against dengue vector. Further studies are needed to identify the possible role of extract as adulticide, oviposition deterrent and ovicidal agent. The isolation of active ingredient from the extract could help in formulating strategies for mosquito control.
authors.affiliation: Department of Zoology, Acharya Narendra Dev College, University of Delhi, New Delhi-110019, India.
authors.forename: Radhika
authors.initials: R
authors.lastname: Warikoo
authors.forename: Ankita
authors.initials: A
authors.lastname: Ray
authors.forename: Jasdeep Kaur
authors.initials: JK
authors.lastname: Sandhu
authors.forename: Roopa
authors.initials: R
authors.lastname: Samal
authors.forename: Naim
authors.initials: N
authors.lastname: Wahab
authors.forename: Sarita
authors.initials: S
authors.lastname: Kumar
mesh_terms: D000330:Aedes / Q000187:drug effects*; D000818:Animals; D032084:Citrus sinensis / Q000378:metabolism*; D003715:Dengue / Q000635:transmission; D004199:Disease Vectors; D005260:Female; D007306:Insecticides / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects; D009032:Mosquito Control / Q000379:methods*; D010936:Plant Extracts / Q000494:pharmacology*; D018515:Plant Leaves / Q000378:metabolism
chemical_list: D007306:Insecticides; D010936:Plant Extracts
keywords: Aedes aegypti; Citrus; Citrus sinensis; Dengue vector; Hexane; Irritancy; Irritant activity; Larvicidal activity; Larvicide; Mosquito control; Take-offs