Resistencia de la garrapata del bovino Rhipicephalus (Boophilus) microplus a los acaricidas utilizados en explotaciones bovinas de la provincia de Loja

Abstract

Abstract:In this study, the resistance of Rhipicephalus (B.) microplus to synthetic acaricides amitraz, ethion, chlorpyrifos, cypermethrin, dichlorvos, ivermectin and deltamethrin, currently used in cattle farms of Loja province, was evaluated. Larval package (LPT) and adult immersion (AIT) tests were carried out with serial dilutions based on both recommended (DR) and discriminant (DD) doses. The mortality values in larvae and adults were evaluated; the reproductive index and the inhibition of oviposition (IO) in treated-engorged females were also studied. By the LPT, the mortality values were > 90% using amitraz and dichlorvos; resistance to chlorpyrifos was detected in 75% of the farms but to ethion, cypermethrin, ivermectin and deltamethrin in all the farms. By the AIT, the IO values were 29.4; 40.9; 21.7 and 25.7 (amitraz; ethion, chlorpyrifos and cypermethrin, respectively); values of IO using dichlorvos, ivermectin and deltamethrin were irrelevant. All the treated-engorged females survived until 10 days, except those treated with chlorpyrifos. Finally, amitraz and dichlorvos were the most effective compounds on larval mortality; a variable resistance was demonstrated in engorged female ticks treated with seven synthetics, industrial acaricides.