Antibiosis and antixenosis among forage species and larvae of cattle tick

Abstract

Two tropical forage legumes, Stylosanthes scabra Vog. and Stylosanthes viscosa Sw., and three grass species, Melinis minutiflora Beauv. (molassses grass), Brachiaria ruziziensis Germain et Evrard, and Pennisetum purpureum grown in a greenhouse, were studied in relation to their capacity of developing antibiosis and antixenosis mechanisms with infestant larvae of the cattle tick B. microplus (Canestrini, 1887). One hundred larvae were placed on each plant and the effects on larvae behavior- were evaluated after 5, 10 and 20 days of contact. M. minutiflora, S. viscosa and S. scabra, that hold epidermic glandular hairs, showed mechanisms of antixenosis (by repelling) and antibiosis (by causing death or holding arrested larvae to their secretions) on the larvae. Among these species potentially useful for the biological control of the cattle tick, molasses grass showed the greatest promise, reducing by 95% the initial population of the cattle tick. P. purpureum and B. ruziziensis developed few or none interference on the behavior of the larvae, showing in this way to be of little use for the biological control of cattle tick.