Location: Livestock Arthropod Pests ResearchTitle: Resistance profile of the cattle-fever tick Rhipicephalus microplus to acaricides in a farm from Arauca, Colombia
|VILLAR, DAVID - University Of Antioquia|
|RODRIGUEZ-DURAN, ARLEX - National University Of Colombia|
|KLAFKE, GUILHERME - Department Of Energy|
|BOSSIO, FELIPE - National University Of Colombia|
|Perez De Leon, Adalberto - Beto|
|CORTES-VECINO, JESUS - National University Of Colombia|
|CHAPARRO-GUTIERREZ, JENNY - University Of Antioquia|
Submitted to: Medical and Veterinary Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/31/2019
Publication Date: N/A
Interpretive Summary: Synthetic chemicals that can kill ticks, or acaricides, are used intensely in Colombia to control the southern cattle fever tick (SCFT) infesting livestock, which is also a vector of the microbes causing bovine babesiosis and anaplasmosis. This tick and associated tick-borne diseases impede the development of cattle raising using breeds with high yields of beef or milk. The high selective pressure associated with intense treatment schedules has rendered the acaricide products commercially available to producers ineffective. In most cases, this is due to SCFT populations that became resistant to the chemical treatments. Of grave concern is the emergence of multiple resistance to acaricides among SCFT populations and the environmental and public health consequences associated with the indiscriminate use of chemicals to treat tick infestations. This situation was investigated in SCFT impacting the health and productivity of livestock in the state of Arauca testing field collected ticks and using ticks from a strain established in the laboratory called Arauquita. The molecular assays produced the first description of gene mutations associated with pesticide resistant SCFT in Colombia. Research outcomes revealed resistance to compounds in the pyrethroid class of acaricides. A novel mutation associated with pyrethroid resistance was discovered and is reported for the first time in SCFT from South America. This information can be used for the rational use of acaricides to treat SCFT infestations in the Colombian state of Arauca.
Technical Abstract: Intensive use of chemical acaricides for the control of cattle ticks (Rhipicephalus microplus) has led to the development of multiple acaricide resistance in Colombia. The objective of this study was to characterize, using toxicological bioassays and molecular biology techniques, the resistance profile of a tick strain isolated from the Arauca state, Northeast Colombia. Commercial acaricides were used in adult immersion tests to determine its in vitro efficacies. Deltamethrin showed very low activity (4-7.3%), a mixture of cypermethrin and chlorpyrifos had intermediate efficacy (64-75.2%), and ethion presented the higher activity (88.5-100%). A colony (Arauquita strain) was established and larval immersion tests confirmed high resistance level to deltamethrin (241-fold) and susceptibility to ivermectin. A qPCR-HRM technique was used to identify nucleotide substitutions in the para-sodium channel gene. All the genotyped individuals were mutant, presenting one (n=7), two (n=7) or three (n=9) SNPs previously associated with pyrethroid resistance. Sequencing revealed a novel mutation (F712L), that was found for the first time in R. microplus ticks from South America. This is the first description of mutations associated with pyrethroid resistance in R. microplus from Colombia. The acaricide resistance pattern found in the Arauquita strain is similar to those reported for other parts of Colombia.