A new approach to characterization of the resistance of populations of Rhipicephalus microplus (Acari: Ixodidae) to organophosphate and pyrethroid in the state of Minas Gerais, Brazil

Abstract

h i g h l i g h t sOf the 587 populations tested for pyrethroids, 97.44% were resistant. For organophosphates were tested 306 populations and 75.49% were resistant. Into populations resistant to pyrethroids, 91% are heterozygous. The analysis confirmed the serious problem of resistance of Rhipicephalus microplus populations. g r a p h i c a l a b s t r a c t a b s t r a c tThe monitoring of resistance of cattle tick populations in Brazil to the chemical bases in use is largely limited to investigation of the phenotypic profile. There are few studies investigating the role played by the genotypic profile in acaricide resistance in the country. Therefore, the aim of the present study was to carry out molecular characterization and trace out the genetic profile of populations of Rhipicephalus microplus with respect to resistance to the organophosphate and pyrethroid chemical groups. For that purpose, larvae were genotyped belonging to 587 populations for pyrethroids and 306 for organophosphates, using the polymerase chain reaction technique. It was found that 75.49% and 97.44% of the larvae studied showed resistance to the organophosphates and pyrethroids, respectively. Among the populations resistant to pyrethroids, 91.9% were heterozygotes, showing that most of the resistant populations have only one allele responsible for resistance. Therefore, it is possible to conclude that the genotyped populations have high resistance to organophosphates, and even more so to pyrethroids. This information is fundamental for understanding the mechanisms of resistance of R. microplus to acaricides, to enable improvement of control techniques.

Management and control of parasites on dairy farms in northwestern region of São Paulo state

“…However, more than half (65%) of the farmers considered that they were satisfied with their tick control. Given the increasing resistance of ticks to commercial products (DAHER et al, 2012;UENO et al, 2012;MENDES et al, 2011;FAZA et al, 2013), the fact that most of these farmers were satisfied with their tick control must have been due to the crossbreeding of their herds (European x Zebu), which was present on 82.5% of the farms (Table 2). Bertolucci (2010) also found that more than half (58.8%) of the dairy producers in the south of the State of Minas Gerais reported that they were relatively satisfied with their tick control and, in that study too, crossbred cattle formed the majority (73.6%).…”

“…(B.) microplus (FAZA et al, 2013;BRITO et al, 2015). In the survey by Amaral et al (2011b) in the State of Minas Gerais, use of alternative control methods such as homeopathy was cited by 3.1%.…”

“…They apply chemical products incorrectly, using incorrect equipment and at a higher frequency than needed, and especially, without technological practices (SANTOS et al, 2000(SANTOS et al, , 2009MENDES et al, 2008;BERTOLUCCI, 2010;AMARAL et al, 2011a, b;ROCHA et al, 2006ROCHA et al, , 2011. Among the most dangerous consequences of incorrect use of acaricides are fast development of resistant strains (SANTOS et al, 2009;MENDES et al, 2011;FAZA et al, 2013) and presence of chemical residues. These residues can be detected in cattle tissues (REZENDE et al, 2013), in workers who do the applications (SILVA et al, 2012) and in the environment (KUNZ & KEMP, 1994).…”

Effects of different spray formulations on the reproductive parameters of engorged Rhipicephalus (Boophilus) microplus females detached from experimentally infested cattle

“…Rhipicephalus (Boophilus) microplus is considered the most important ectoparasite in the cattle industry because of the direct and indirect damage that it can cause to animal health, which considerably limits bovine productivity (Calligaris et al, 2013;Maza et al, 2013). It has a wide geographic distribution, spanning tropical and subtropical regions between parallels 32 • N latitude and 35 • S latitude, including countries in Latin America, Africa, Asia and Oceania (Wharton et al, 1970).…”

Effect of a spray formulation on the reproductive parameters of a susceptible population of Rhipicephalus (Boophilus) microplus

“…Rhipicephalus (Boophilus) microplus is considered to be the most important ectoparasite in cattle industry because of the direct and indirect damage it can cause to animal health, thereby considerably limiting bovine productivity (CALLIGARIS et al, 2013;FAZA et al, 2013). It possesses a wide geographical distribution, encompassing tropical and subtropical regions situated between the parallels 32° latitude north and 35° latitude south, comprising countries in Latin America, Africa, Asia and Oceania (WHARTON, 1974).…”