title: Syringe test (modified larval immersion test): a new bioassay for testing acaricidal activity of plant extracts against Rhipicephalus microplus.
abstract: We report a new bioassay "syringe test" (modified larval immersion test) for in vitro evaluation of acaricidal activity of crude plant extracts. Prepared syringes, containing eggs of tick, were incubated until 14 d after hatching of eggs, when the bioassay was performed on the larvae. Lethal concentrations for 50% of larvae (LC(50)), LC(90) and LC(99) values were calculated for each tested product. 95% confidence intervals for LC(50) were very narrow, indicating a high degree of repeatability for the new bioassay on larvae of R. microplus. Bioassays were applied to six crude aqueous-methanol extracts from five plants (Acacia nilotica, Buxus papillosa, Fumaria parviflora, Juniperus excelsa, and Operculina turpethum), of which three showed discernible effects. Twenty-four hours post exposure, LC(99) values were 11.9% (w/v) for F. parviflora, 20.8% (w/v) and 29.2% (w/v) for B. papillosa and A. nilotica, respectively. After six days of exposure these values were; 9.1% (w/v), 9.2% (w/v) and 15.5 (w/v) for F. parviflora, A. nilotica and B. papillosa, respectively.
authors.affiliation: Chemotherapy Laboratory, Department of Parasitology, University of Agriculture, Faisalabad 38040, Pakistan. ziasandhu@hotmail.com
authors.forename: Zia-ud-Din
authors.initials: ZU
authors.lastname: Sindhu
authors.forename: Nicholas N
authors.initials: NN
authors.lastname: Jonsson
authors.forename: Zafar
authors.initials: Z
authors.lastname: Iqbal
mesh_terms: D056810:Acaricides / Q000302:isolation & purification / Q000494:pharmacology*; D000818:Animals; D001681:Biological Assay / Q000379:methods*; D031234:Buxaceae / Q000737:chemistry; D027722:Convolvulaceae / Q000737:chemistry; D007887:Fabaceae / Q000737:chemistry; D005260:Female; D031312:Fumaria / Q000737:chemistry; D007101:Immersion; D018653:Juniperus / Q000737:chemistry; D007814:Larva; D007928:Lethal Dose 50; D019684:Magnoliopsida / Q000737:chemistry*; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry; D015203:Reproducibility of Results; D048494:Rhipicephalus / Q000187:drug effects*; D012680:Sensitivity and Specificity; D013984:Tick Infestations / Q000469:parasitology*
chemical_list: D056810:Acaricides; D010936:Plant Extracts