RESUMO Foram realizados testes laboratoriais para avaliar a eficiência do extrato de raízes da planta Dahlstedtia pentaphylla (Taub.) Burk., (Leguminosae, Papilionoideae, Millettiae) sobre amostras de Boophilus microplus (Canestrini, 1887) de bovinos da região do Vale do Paraíba e da cepa sensível Mozo. Os testes foram efetuados sobre teleóginas (fêmeas ingurgitadas) e larvas não alimentadas. A diluição padrão foi feita na proporção de uma parte do pó das raízes para três partes do solvente, considerada como solução 100%. Visando determinar o solvente mais eficiente para a extração de rotenóides das raízes, conduziram-se testes laboratoriais sobre teleóginas de B. microplus em três solventes: água, etanol p.a e acetona p.a. Para as larvas da cepa local (Polo Regional do Vale do Paraíba) a DL50 calculada foi de 1: 231,37 mL e DL90 1: 85,24 mL. A CE90 para as teleóginas, da mesma cepa, foi de 1: 10,19 mL e a CE50 1: 34,94 mL. Para teleóginas da cepa sensível Mozo a CE90 foi de 1: 23,91 mL e a CE50, 1: 60,46 mL. A mortalidade das teleóginas frente aos diferentes solventes foi avaliada. Taub. Taub (Taub. Burk Burk. Leguminosae, Leguminosae (Leguminosae Papilionoideae Millettiae Canestrini, Canestrini (Canestrini 1887 fêmeas ingurgitadas alimentadas 100 100% conduziramse conduziram se B água pa p Polo DL DL5 1 23137 231 37 231,3 DL9 8524 85 24 85,2 CE CE9 1019 10 19 10,1 CE5 3494 34 94 34,9 2391 23 91 23,9 6046 60 46 60,4 avaliada (Taub 188 2313 3 231, 852 8 2 85, 101 10, 349 9 34, 239 23, 604 6 4 60, 18

ABSTRACT Laboratory trials were performed to evaluate the efficiency of Timbo root extract (Dahlstedtia pentaphylla) (Taub). Burk. (Leguminosae, Papilionoidae, Millettiedae) on samples of Boophilus microplus (Canestrini, 1887) in bovines of the Paraíba Valley region - São Paulo, Brazil. The trials were carried against engorged females and larvae. The standard dilution was made from one part of root powder and three parts of ethanol, which was considered the 100% solution. To determine the most efficient solvent to extract rotenone from the root, laboratory trials were conducted on B. microplus engorged females with three solvents: water, ethanol a.p. and acetone a.p. The laboratory trials permitted the calculation of lethal doses at 90% (LD90) and 50% (LD50) for larvae between the seventh and fourteenth days of application and efficient concentrations at 90% (EC90) and 50% (EC50) on local strain and Mozo strain of B. microplus engorged females. For the larvae of the local strain (Regional Polo of Paraíba Valley) calculated LD50 was 1: 231.37 mL and LD90 was 1: 85.24 mL. The EC90 for engorged females of the same strain was 1: 10.19 mL and the EC50 1: 34.94 mL. For the engorged females on the hypersensitive strain Mozo the EC90 was 1: 23.91 mL and the EC50 1: 60.46 mL. The mortality of engorged females in relation to the different kinds of solvent was analyzed. Dahlstedtia pentaphylla Taub. Taub . (Taub) Burk Leguminosae, Leguminosae (Leguminosae Papilionoidae Millettiedae Canestrini, Canestrini (Canestrini 1887 Paulo Brazil 100 solution B solvents water ap a p a.p 90 LD (LD90 50 (LD50 EC (EC90 (EC50 Regional LD5 1 23137 231 37 231.3 LD9 8524 85 24 85.2 EC9 1019 10 19 10.1 EC5 3494 34 94 34.9 2391 23 91 23.9 6046 60 46 60.4 analyzed (Taub 188 9 (LD9 5 (LD5 (EC9 (EC5 2313 3 231. 852 8 2 85. 101 10. 349 34. 239 23. 604 6 4 60. 18 (LD (EC