Cross-resistance between macrocyclic lactones in populations of Rhipicephalus microplus in Brazil’s semiarid region

• Published in: Experimental & applied acarology Vol. 87; no. 1; pp. 109 - 117
• Main Authors: Ferreira, Larissa Claudino, Lima, Estefany Ferreira, Silva, Ana Luzia Peixoto, Oliveira, Clarisse Silva Menezes, Silva Filho, Geraldo Moreira, Sousa, Luana Carneiro, Klafke, Guilherme Marcondes, Feitosa, Thais Ferreira, Vilela, Vinícius Longo Ribeiro
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01-05-2022; Springer Nature B.V
• Subjects: Acaricides; Animal Ecology; Animal Genetics and Genomics; Animal Systematics/Taxonomy/Biogeography; Bioassays; Biomedical and Life Sciences; Cattle; Control methods; Cross-resistance; Drug resistance; Ectoparasites; Eggs; Entomology; Epidemiology; Farms; Humidity; Ivermectin; Laboratories; Lactones; Life Sciences; Parasites; Parasitology; Populations; Rhipicephalus microplus; Semi arid areas; Semiarid lands; Brazil; Acaricides; Eprinomectin; Cattle tick; Moxidectin; Ivermectin
• ISSN: 0168-8162; 1572-9702
• DOI: 10.1007/s10493-022-00730-x

Rhipicephalus microplus
, also known as the cattle tick, is the parasite with the greatest impact on cattle in Brazil. The most common method for controlling this tick is the application of synthetic chemical acaricides, especially ivermectin, which belongs to the group of macrocyclic lactones (MLs). However, because ivermectin is widely used, there is concern about the development of cross-resistance within this chemical class. Thus, engorged females were collected from farms with a history of resistance to ivermectin, which was the only one among the MLs that was used as an endectocide drug. Using larval immersion tests (LIT), bioassays were performed with ivermectin, moxidectin and eprinomectin on populations of
R. microplus
from the semiarid region of the states of Paraíba and Ceará, Brazil. Epidemiological questionnaires were applied to collect information about tick control management. All the evaluated populations showed cross-resistance between ivermectin and moxidectin, but only one population showed cross-resistance between ivermectin and eprinomectin. Weekly or monthly administration of injectable 1% ivermectin on farms was reported. It was concluded that the frequent use of ivermectin may lead to the development of cross-resistance to moxidectin. For eprinomectin, despite the structural similarity, cross-resistance was not observed in three tick populations.