Efficacy of acaricides against larvae of Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) and Rhipicephalus (Boophilus) microplus (Canestrini, 1887) (Acari: Ixodidae)

Abstract

Parasitism by mites has always been of concern with regard to losses in animal production and to the transmission of etiologic agents of important diseases as well, and about 95% of the developing forms of ticks in the non-parasitic phase are in the environment. In view of the importance of controlling larval stages of ticks in the environment, this study evaluated the efficacy of acaricides in vitro against larvae of Rhipicephalus (B.) microplus and R. sanguineus. Accordingly, we tested: 15% cypermethrin (T1); 25% deltamethrin (T2); combination of cypermethrin 5% + 45% dichlorvos + 25% piperonyl butoxide (T3); combination of 15% cypermethrin + 25% chlorpyrifos + 1% citronella (T4); and 12.5% amitraz (T5). In each treatment, there were nine replicates with 20 larvae each. The larvae were observed for motility at: 1, 5, 10, 20 and 30 minutes post-treatment (MPT); 1, 2, 6, 12 and 24 hours post-treatment (HPT); and 5 days post-treatment. Tests in R. (B.) microplus and R. sanguineus larvae with 25% deltamethrin served as a positive control and demonstrated 100% loss of motility at 2 HPT for both tick species. R. (B.) microplus larvae were most sensitive to treatments containing 15% cypermethrin or 5% cypermethrin combined with dichlorvos and piperonyl butoxide. Larvae of R. sanguineus were most sensitive to treatment with 12.5% amitraz. However, despite the differences in acaricidal effect during the observation time, 100% efficacy was obtained for all treatments against larvae of R. sanguineus and R. (B.) microplus at 12 HPT, demonstrating that appropriate doses of commercial acaricides can be effective in environmental control strategies against tick larvae.

Keywords

• Antiparasitários
• Bovinos
• Cães
• Carrapatos
• Ixodídeos
• Larvicidas