efficacy the mixture of two strains of metarhizium anisopliae (deuteromycotina: hyphomycetes) to control rhipicephalus microplus on natural infestation of cattle

The objective of the present study was to evaluate the efficacy of Metarhizium anisopliae on the control of Rhipicephalus microplus in cattle infested naturally in the Mexican tropics. The study was carried out on a ranch in the Mexican tropics. Base on the number of adult and immature (larvae and nymphs) R. microplus ticks 20 steers were assigned into two groups of 10 cattle. Animals in the treated group (average of 73.4 y 27.5 adult and immature ticks respectively) were sprayed with a mixture of Ma14+Ma34 of M. anisopliae at a concentration of 1x108 conidios/ml. The other group remained as untreated control (average of 77.7 y 24.7 adult and immature ticks respectively) and treated with water+Tween 80. Each group received 4 applications every 14 days. Adult and immature stages of ticks were recorded on days 0, 3, 5, 7 and 14 post-treatment. From the first application treatment to the end of the experiment, animals in the treated group had lower counts (P < 0.05) of adult (30.9-87%) and immature (35.8-72%) ticks. The results demonstrate the efficacy of repeated treatment with the strains Ma14+Ma34 of M. anisopliae can be used as an alternative to control natural infestation of R. microplus on cattle in the Mexican tropics.