Ingreso y evolución del parasitismo por Melophagus ovinus en una majada Corriedale en el noroeste de la Patagonia Argentina

Abstract

An infested ram was introduced during mating (for 2 weeks) into a non-infested Corriedale sheep flock. The rate at which keds were disseminated, was measured by tallying number of infected sheep and counting ked burden on days 0, 220 and 433. To evaluate potential growth of Melophagus ovinus populations within the fixed-sized sheep flock during the study period, we built a simple population model. Initial counts (day 0), were of 4 M. ovinus adults and 3 pupae on a single sheep, whereas on day 220 parasitism reached 100% in lambs remaining at these values throughout the study period. In contrast, adult sheep showed low but rising counts, reaching 91% on day 433. According to the model, expected M. ovinus populations were 193 fold larger. We assign this difference to limitations on population growth set by environmental factors and sheep management such as shearing, lambing and lamb sales. © 2006 Sociedad Chilena de Parasitolog. Organo Oficial de la Federación Latinoamericana de Parasitólogos.