Effect of different concentrations of citronella oil and tincture on reproductive parameters of Rhipicephalus (Boophilus) microplus teleoginesEfeito de diferentes concentrações de óleo e tintura de citronela sobre os parâmetros reprodutivos de teleóginas de Rhipicephalus (Boophilus) microplus

The tick Rhipicephalus (Boophilus) microplus is the most important ectoparasite in cattle rising, and it is responsible for severe economic losses. Parasite control is based on chemicals, which are used indiscriminately and result in effectiveness reduction of these compounds. In order to delay the onset of parasite resistance, some alternative methods are being researched, including herbal medicine. The aim of this experiment was to evaluate the in vitro efficacy of citronella (Cymbopogon nardus) oil and tincture on R. (B) microplus by the engorged female immersion test. Four oil concentrations were tested (1; 25; 50; 100%) and the inhibition of oviposition were 16; 40; 53; 73%, egg hatch were 28; 16; 23; 6% and the effectiveness were 78; 100; 86; 98%, respectively. The gradual rise of the inhibition of oviposition and low egg hatch had a positive influence in the effectiveness of treatment. The solution at 1% of citronella oil had a partial control of the teleogines and the solution at 25% had 100% of effectiveness. Six dilutions of the tincture (1; 5; 10; 25; 50; 100%) were tested and the inhibition of oviposition were 10; 63; 80; 83; 86; 96%, egg hatch were 91; 31; 6; 26; 0; 0% and the effectiveness were 23; 93; 94; 97; 100; 100%, respectively. Most of the treatments with the citronella tincture had inhibition of oviposition higher than 80% and low egg hatch rate. The tincture at 5% had similar efficacy compared to the groups with higher concentrations. A significant association between the oil and tincture of citronella and the treatment effectiveness was observed in the statistical evaluation. It is possible to conclude that both the oil and the tincture of citronella had negative influence in the reproductive parameters of R. (B) microplus. O carrapato Rhipicephalus (Boophilus) microplus é o ectoparasito mais importante em áreas de exploração pecuária, sendo responsável por severas perdas econômicas. O controle deste parasito é feito através de produtos químicos, que são utilizados de forma indiscriminada e resultam na redução da eficiência destes compostos. A fim de retardar o aparecimento da resistência parasitária, alguns métodos de controle alternativo vêm sendo pesquisados, entre eles a fitoterapia. O objetivo deste experimento foi avaliar a eficiência in vitro do óleo e da tintura de citronela (Cymbopogon nardus) sobre fêmeas ingurgitadas de R. (B) microplus seguindo a metodologia do exame de biocarrapaticidograma. Para isto foram testadas 4 d