Evidence of acaricide resistance in different life stages of Amblyomma mixtum and Rhipicephalus microplus (Acari: Ixodidae) collected from the same farm in the state of Veracruz, Mexico.

The objectives of this study were to evaluate the resistance of Amblyomma mixtum and Rhipicephalus microplus ticks from co-infested bovines from the Veracruz region in Mexico to different acaricide families and to demonstrate the viability of the packet test on different A. mixtum instars. The following acaricide families were used: a combination (cypermethrin 15 g + chlorpyrifos 25 g + citronella 1 g + butoxide piperonyl 15 g), amidine (formamidine 12.5 g), pyrethroid (cypermethrin 15 g), and organophosphate (dichlorvos 60 g + chlorpyrifos 20 g). Regarding the packet test in both species, resistance was found for the pyrethroid and amidine families in A. mixtum and R. microplus, as efficacy did not surpass 40 %, including in immature instars; regarding the adult immersion test in R. microplus, the efficacy was 93.3 % for the amidine family and 26.2 % for the pyrethroid family. The proposed methodology is an alternative technique to optimize resistance detection in immature ticks with a heteroxenous life cycle.