Inheritance of resistance to flumethrin in the Mexican Aldama strain of the cattle tickBoophilus microplus(Acari: Ixodidae)

Abstract

The objective of this study was to evaluate the inheritance mode of resistance to flumethrin in the Mexican Aldama Boophilus microplus strain. Two Mexican strains were used, the Chiapas susceptible (SS), and the Aldama flumethrin-resistant from Tamaulipas. Six steers weighing ca. 250 kg were randomly assigned for each of six crosses: the susceptible (SS), resistant (RR), and the F1 (RS, SR) reciprocal crosses and F2 (RS x RS and SR x SR). The reciprocal crosses were made to evaluate maternal and sex linkage effects. Bioassays tested resistant and susceptible larvae along with their hybrid F1 and F2 progeny against a series of concentrations of flumethrin (0, 0.0075, 0.00150, 0.00300, 0.00600 and 0.01200 microg/g). To test the single-gene hypothesis of resistance, a nonparametric line-cross test proposed by Collins was used. The bioassay data were subjected to probit analysis and the resistance factor and effective dominance obtained. Results of this study indicated that inheritance for flumethrin resistance in the Aldama strain was autosomal and controlled for more than one gene. The F1 and F2 larvae had similar lower resistant factor (RF 2.8-4.5) while the resistant Aldama strain was 21-fold higher (RF 81.8) than the mean of the F1 and F2. The extent of flumethrin resistance in the Aldama B. microplus strain depended upon the concentration of the pesticide used. Resistance was almost dominant at the lowest dose while almost completely recessive at the highest dose. Maternal effects were shown for egg-mass. These results shown here indicate more than one gene basis of flumethrin resistance in B. microplus ticks are present. Therefore it is necessary to locate and understand the major loci for elucidate the mechanism of resistance and improve the ability to track and delay the evolution of resistance.

Mode of Inheritance of Amitraz Resistance in a Brazilian Strain of the Southern Cattle Tick, Boophilus microplus (Acari: Ixodidae)*

“…Compared with autosomally inherited traits, the sexlinked resistance may enhance or retard the rate of evolution of resistance (McDonald and Schmidt 1990;Daly and Fisk 1998). Tapia-Perez et al (2003) observed reduced egg mass weight in a pyrethroidresistant strain of B. microplus, which was suggested to be a resistance-related fitness cost. Within our laboratory conditions, the Santa Luiza strain had a higher reproductive capacity than the Mun˜oz strain, as demonstrated by the measured biological parameters ( Table 2).…”

“…The expected mortality of the F 2 generation of both type-I and type-II crosses at each amitraz concentration was estimated using the formula X = (0.25)W (S strain) + (0.25)W (F 1 type-I) + (0.25)W (F 1 type-II) + (0.25)W (R strain) . The relationships between the observed and expected mortality in both backcross and F 2 generations were analyzed by v 2 goodness-of-fit analysis, using procedures described by Tabashnik (1991) and Tapia-Perez et al (2003), respectively.…”

“…Similarly, resistance to organochlorine was found to be inherited as a single, near-complete dominant gene in two other tick species, Amblyomma variegatum (F.) and Rhipicephalus appendiculatus Neumann (Lourens 1979(Lourens , 1980. A recent study on flumethrin resistance in a Mexican strain of B. microplus demonstrated that resistance to flumethrin was controlled by more than one gene, and expressed as a recessive or dominant trait depending on the flumethrin concentration exposed (Tapia-Perez et al 2003). The results of our current study revealed a different mode of inheritance for amitraz resistance in B. microplus.…”

Inheritance of pyrethroid resistance and a sodium channel gene mutation in the cattle tick Boophilus microplus

“…As a result, no LC 50 was calculated. Tapia-Pérez et al (2003) have found that resistance to flumethrin is controlled by more than one gene without maternal effect. Conversely, our results, regarding the RS (RR♂×SS♀) strain resistance profile, do not support this statement, at least for flumethrin (100% mortality) and deltamethrin (100% mortality), because in both cases, the effective dominance of the mortality level was zero (D ML = 0) which means that inheritance of resistance is completely recessive when the male is resistant.…”

Desarrollo de un programa en hoja de cálculo para obtener el umbral económico de acaricidas como apoyo en el control de la garrapata Rhipicephalus microplus

“…En general, un número bajo de garrapatas no causan un daño importante; de hecho, mantener bovinos en la explotación sin tratar con acaricidas, podría ser deseable para mantener poblaciones de garrapatas susceptibles (refugio), que al hibridarse con las resistentes, puedan eliminarse fácilmente (33) ; pero para ello es indispensable analizar en cada explotación, la cantidad de garrapatas presentes por bovino, ponderando el impacto económico de éstas sobre los costos corrientes de gestión. Los umbrales también proporcionan un punto de partida para conocer el estatus de la explotación, son números únicos, específicos para cada una.…”