Efficacy of extracts from plants of the Brazilian Pantanal against Rhipicephalus (Boophilus) microplus.

This research evaluated the in vitro acaricidal activity of extracts from 21 plant species from the Pantanal of Mato Grosso do Sul. During stage I, a larval immersion test was performed using three extract concentrations (5%, 20%, and 40%). During stage II, we used only plants that showed over 95% efficiency at the 40% concentration in stage I in an amount sufficient for the adult immersion test. Aeschynomene denticulata, Angelonia hirta, Aspilia latissima, Caperonia castaneifolia, Centratherum punctatum, Crotalaria micans, Diodia kuntzei, Echinodorus paniculatus, Hyptis mutabilis, Lantana canescens, Melanthera latifolia, Ocotea diospyrifolia, Richardia grandiflora, Sebastiana hispida, Tocoyena formosa, Zanthoxylum rigidum, and Sesbania virgata (fruit extract) showed acaricidal activity against the larval stage of Rhipicephalus (Boophilus) microplus higher than 95% at a 40% (w/v) concentration, while Hippocratea volubilis and Randia armata showed moderate efficacy and Croton glandulosus and Senna obtusifolia had no effect. The M. latifolia, A. hirta, R. grandiflora, and A. latissima raw extracts were evaluated for their activity against adults, and only A. hirta showed an efficacy close to 90%. Eighteen extracts had an efficacy of up to 95% against larvae at a 40% concentration, seven extracts were effective at 20%, and only one (Sebastiana hispida) was effective at a 5% concentration.