Compatibility between the entomopathogenic nematode Steinernema glaseri (Rhabditida: Steinernematidae) and an acaricide in the control of Rhipicephalus (Boophilus) microplus (Acari: Ixodidae).

There have been studies of the compatibility between entomopathogenic nematodes and insecticides commonly used to control crop pests, but this same approach has not been widely studied regarding the control of ticks. Therefore, this work examines the association between a species of entomopathogenic nematode, Steinernema glaseri, and an organophosphate acaricide to control the cattle tick Rhipicephalus microplus. Engorged females were separated into 12 groups, with ten repetitions each, immersed for 5 min in varied concentrations of acaricide (commercial dose and one-half, one-fourth, one-eighth and one-sixteenth of that dose), associated or not with the nematodes, maintained under controlled conditions. There were two control groups, one containing nematodes and water and the other only water. The absence of egg laying and significant reduction in the survival period of the females in the nematode treatments associated with the lowest acaricide doses demonstrated the compatibility between the two agents. We observed the presence of S. glaseri adults on the cuticle of the females in the treatments with one-eighth and one-sixteenth the commercial dose. These results indicate greater efficacy of the treatments with lower acaricide concentrations in association with S. glaseri, with less environmental impact, reduced costs and less resistance selection pressure on the tick populations.