ACARICIDAL ACTIVITY OF THE ESSENTIAL OIL OF AGERATUM CONYZOIDES (Linnaeus, 1753) ON LARVAE OF RHIPICEPHALUS SANGUINEUS (Latreille, 1806) IN VITRO

Abstract

Ticks are ectoparasites of veterinary importance because they transmit blood parasites such as Babesia sp, Anaplasma spp, and Ehrlichia spp. for dogs. The essential oil of Ageratum conyzoides, popularly known as mentrasto, has repellent and insecticidal activity of great interest to Public Health, with its majority components being precocene I and precocene II. The objective of this work was to evaluate the in vitro insecticidal activity of A. conyzoides on Rhipicephalus sanguineus larvae. Teleogynes of R. sanguineus were collected, washed, dried and fixed in Petri dishes. After laying, the eggs were collected and placed in adapted syringes and kept at room temperature (average of 27.6°C). After the eggs hatched, 100 tick larvae were placed in each filter paper envelope impregnated with 3 concentrations (25mg/ml, 50mg/ml and 100mg/ml) of A. conyzoides essential oil to determine the acaricidal activity index. For negative control, a 10% hydroalcoholic solution was used and for positive control, cypermethrin (Barrage®) diluted according to the manufacturer's specifications was used. The LC50 and LC99 for A. conyzoides EO were 0.18 mg/ml and 39.7 mg/ml, respectively, in this experiment. It is concluded that the essential oil of A. conyzoides has good acaricidal action on the larvae of the tick R. sanguineus.