Abstract

Ticks (Boophilus sp) are one of the main problems that affect the performance of bovine production in tropic and sub-tropical. Organophosphate acaricides are the usual tick control method, however the ecological damage and cross-resistance to those acaricides is leading to the search for alternatives. Beauveria bassiana can be used as a biological control, however, laboratory bioassays with ticks showed mortality of 20 to 50% only. The aim of this investigation was to study the effect of five strains of Beauveria sp, two conidial concentrations and three immersion times on mortality rate of ticks. Five strains of Beauveria sp isolated in México were used and cultivated in liquid medium until 107 and 108 conidia/mL were obtained. For in vitro bioassays, ticks were collected from bovine, immersed in conidial suspensions for 20, 30 and 40 seconds. Mortality rate was recorded daily up to 10 days. Strain type was the main factor and 23-D Beauveria strain had the highest value (100%) of mortality rate after ten days of incubation with ticks. The best immersion time was 20 s and the best conidial concentration was 108 conidial/ml. In conclusion, native Beauveria sp strains could be an alternative viable for ticks control in bovine, however field test and Beauveria identification are necessary.

Key words: Bovine ticks, biological control, in vitro bioassays, native Beauveria sp strains