Controle integrado de nematódeos de ruminantes com a utilização de bactérias e fitoterápicos

Abstract

This study aimed to evaluate alternatives of integrated control to the gastrointestinal nematodes (GIN) of ruminants. In the first stage, in vitro tests were performed, in order to confront Bacillus circulans (Bcir), B. thuringiensis var. osvaldocruzi (Bto), B. thuringiensis var. israelensis (Bti) e B. thuringiensis var. kurstaki (Btk) against nematodes. All species of Bacillus showed larvicidal effect (≤ 60%). Bcir and Bti were incubated with anthelmintics (moxidectin, nitroxynil and levamisole) and maintained their viability. The best result in the two previous tests was obtained with Bti, which was evaluated in vivo in young cattle naturally infected with GIN. Group I treated with Levamisole (antihelmintic), group II with Bti, group III with Bti associated with Levamisole and group IV Control (untreated). Efficacy was established by comparing the number of larvae recovered before treatment (hour zero) and after (24, 48 and 72 hours). The nematicidal potential of Bti in vivo of 84% was observed at 24h. Idealizing the association of more than one parasitic control alternative, in vitro tests of inhibition of hatchability and larval migration of GIN of ovine species against Rosmarinus officinalis essential oil were carried out and tested in six concentrations (227,5mg/mL; 113,7mg/mL; 56,8mg/mL; 28,4mg/mL; 14,2mg/mL; 7,1mg/mL). In the chromatographic analysis of this oil, 18 constituents were identified, the majority being Eucalyptol (1,8-cineole) with 42.11%, (+) - 2-Bornanone with 16.37% and alpha.-Pinene with 14.76%. In vitro tests, R. officinalis oil inhibited 100% hatchability at the four highest concentrations and reached 70% and 74% inhibition of larval migration at the two highest concentrations, respectively. The inhibitory concentration of 50% (IC50) of the oil on the eggs was 0.5181 mg / mL, while the IC50 of larval inhibition was 62.17 mg / mL. This study determined the nematicidal action of four species of Bacillus in vitro and the same in vivo effect of Bacillus thuringiensis var. israelensis, as well as the ovicidal and larvicidal action of the essential oil of Rosmarinus officinalis, which allows to conclude that these two alternatives have potential for the use in the control of GIN of ruminants.