title: Potential of the insect growth regulator, fluazuron, in the control of Rhipicephalus sanguineus nymphs (Latreille, 1806) (Acari: Ixodidae): determination of the LD95 and LD50.
abstract: Conventional pesticides have suffered two main drawbacks: (a) broad spectrum of action and (b) selection of target species resistant to the different active ingredients. Thus compounds that are less harmful to the environment and to human health, more specific and that do not induce resistance need to be developed. One alternative are insect growth regulators, such as fluazuron. The present study examined the efficacy of fluazuron (active ingredient of the acaricide Acatak®) and the sensitivity of Rhipicephalus sanguineus nymphs exposed to different doses of this chemical, and determined the lethal doses of fluazuron: 95% - LD(95) and 50% - LD(50). Different doses of fluazuron were applied in duplicates on the dorsal region of hosts ("pour on"). Distilled water was used in the control group. On the first day after the treatment with fluazuron, hosts were artificially infested with R. sanguineus nymphs. After engorgement, nymphs were removed, placed on Petri dishes, identified, and maintained in BOD incubator for 15days. Dead R. sanguineus nymphs after the treatment with 13 different doses of fluazuron were quantified and the LD(95) was estimated to be 100mg/kg and LD(50), 19.544mg/kg (12.478-22.636), with a confidence interval of 95%. Nymphs of R. sanguineus were sensitive to fluazuron at various levels, indicating that this insect growth regulator (IGR) may be used to control this parasite in this stage of its biological cycle, reducing the significant damage it causes.
authors.affiliation: Department of Biology, Institute of Biosciences, São Paulo State University-UNESP, Av 24 A, No 1515, Postal Code 199, 13506-900 Rio Claro, SP, Brazil.
authors.forename: Patrícia Rosa
authors.initials: PR
authors.lastname: de Oliveira
authors.forename: Izabela Braggião
authors.initials: IB
authors.lastname: Calligaris
authors.forename: Gislaine Cristina
authors.initials: GC
authors.lastname: Roma
authors.forename: Gervásio Henrique
authors.initials: GH
authors.lastname: Bechara
authors.forename: Marcos Aparecido
authors.initials: MA
authors.lastname: Pizano
authors.forename: Maria Izabel
authors.initials: MI
authors.lastname: Camargo Mathias
mesh_terms: D000818:Animals; D001681:Biological Assay; D005260:Female; D007605:Juvenile Hormones; D007928:Lethal Dose 50; D009758:Nymph; D010671:Phenylurea Compounds; D011817:Rabbits; D012044:Regression Analysis; D048508:Rhipicephalus sanguineus
chemical_list: D007605:Juvenile Hormones; D010671:Phenylurea Compounds; C104929:fluazuron