Toxicity effect of the acaricide fipronil in semi-engorged females of the tick Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae): Preliminary determination of the minimum lethal concentration and LC

Chemical acaricides, especially fipronil (active ingredient of Frontline®), are still the most effective method to control tick populations. In this study, the effectiveness of fipronil was assessed in semi-engorged females of the tick Rhipicephalus sanguineus. A protocol for an in vitro bioassay (A...

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Bibliographic Details
Published in:Experimental parasitology 2011-02, Vol.127 (2), p.418-422
Main Authors: Oliveira, Patrícia Rosa de, Bechara, Gervásio Henrique, Denardi, Sandra Eloisi, Pizano, Marcos Aparecido, Mathias, Maria Izabel Camargo
Format: Article
Language:English
Subjects:
Acaricides
active ingredients
adults
Animals
bioassays
Biological Assay
confidence interval
Confidence Intervals
Female
females
fipronil
lethal concentration 50
Lethal Dose 50
mortality
parasitology
probit analysis
Pyrazoles
Rhipicephalus sanguineus
tick control
Tick Control - methods
ticks
toxicity
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Summary:Chemical acaricides, especially fipronil (active ingredient of Frontline®), are still the most effective method to control tick populations. In this study, the effectiveness of fipronil was assessed in semi-engorged females of the tick Rhipicephalus sanguineus. A protocol for an in vitro bioassay (AIT) was developed, and the LC₅₀ (lethal concentration 50%) and 95% confidence interval were determined. Ticks were immersed in Petri dishes with different concentrations of fipronil or distilled water for 2min, dried, and placed in an incubator for 7days. Dead R. sanguineus females treated with the 14 concentrations of fipronil were counted daily. Mortality results were compared with the Probit analysis, and the LC₅₀ and 95% confidence interval were calculated, g (95): LC₅₀=9.647 (4.711 to 13.470). This study was aimed at developing a more appropriate and updated protocol for an in vitro bioassay (AIT – adult immersion test), and providing information on the toxic potential of fipronil (elimination of ectoparasites with lower concentrations) and sensitivity of ticks, especially R. sanguineus, a pest of great interest, due to its occurrence in urban environments.
ISSN:0014-4894
1090-2449
DOI:10.1016/j.exppara.2010.09.009