Abstract
Ticks and the diseases they transmit cause great economic losses to livestock in tropical countries. Non-chemical control alternatives include the use of resistant cattle breeds, biological control and vaccines. However, the most widely used method is the application of different chemical classes of acaricides and macrocyclic lactones. Populations of the cattle tick, Rhipicephalus (Boophilus) microplus, resistant to organophosphates (OP), synthetic pyrethroids (SP), amitraz and fipronil have been reported in Mexico. Macrocyclic lactones are the most sold antiparasitic drug in the Mexican veterinary market. Ivermectin-resistant populations of R. (B.) microplus have been reported in Brazil, Uruguay and especially in Mexico (Veracruz and Yucatan). Although ivermectin resistance levels in R. (B.) microplus from Mexico were generally low in most cases, some field populations of R. (B.) microplus exhibited high levels of ivermectin resistance. The CHPAT population showed a resistance ratio of 10.23 and 79.6 at lethal concentration of 50% and 99%, respectively. Many field populations of R. (B.) microplus are resistant to multiple classes of antiparasitic drugs, including organophosphates (chlorpyrifos, coumaphos and diazinon), pyrethroids (flumethrin, deltamethrin and cypermethrin), amitraz and ivermectin. This paper reports the current status of the resistance of R. (B.) microplus to acaricides, especially ivermectin, in Mexican cattle.
Highlights
Chemical acaricides have played an essential role in control of this tick, but intensive acaricide use has favored the development of resistant populations (RODRÍGUEZ-VIVAS et al, 2006a, b)
This paper reports the current status of the resistance of R. (B.) microplus to acaricides, especially ivermectin, in Mexican cattle
In Mexico many field populations of R. (B.) microplus are resistant to multiple classes of antiparasitic drugs, including OPs, synthetic pyrethroids (SP), amitraz and ivermectin
Summary
Rhipicephalus (Boophilus) microplus (R. (B.) microplus) (Canestrini) is an endemic pest of cattle in tropical and subtropical regions of the world, causing major economic losses to cattle producers through direct physical effects on the parasitized animal and indirectly through transmission of infectious disease agents such as Babesia bovis, B. bigemina and Anaplasma marginale (SOLORIO-RIVERA et al, 1999; RODRÍGUEZ-VIVAS et al, 2004, 2005).Chemical acaricides have played an essential role in control of this tick, but intensive acaricide use has favored the development of resistant populations (RODRÍGUEZ-VIVAS et al, 2006a, b). Chemical acaricides have played an essential role in control of this tick, but intensive acaricide use has favored the development of resistant populations (RODRÍGUEZ-VIVAS et al, 2006a, b). Many drug classes have been and are used as acaricides to treat cattle ticks, this include arsenicals, organochlorides (OCs), organophosphates (OPs), carbamates, amidines, phenylpyrazoles, insect growth regulators, synthetic pyrethroids (SPs) and MLs (AGUILAR-TIPACAMU; RODRIGUEZ-VIVAS, 2003; GEORGE et al, 2004).
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