Intensification and Infestation: Agricultural Management and the Parasites of Associated Biodiversity within Agroecosystems

Abstract

A large part of habitat fragmentation is attributed to agriculture, but scarce literature exists that explicitly combines disease ecology, agroecology, and conservation biology. This thesis first reviews existing literature of the three disciplines as they relate to fragmented landscapes. The second part empirically investigates the relationship between coffee management and avian ectoparasite load to better understand the extent to which agricultural management influences parasitism and body condition of birds inhabiting coffee agroecosystems. Coffee accounts for a large part of agricultural land in mid-elevation areas of Latin America, and so shaded coffee agroecosystems have been recognized as potential refuges of biodiversity (Perfecto et al. 1996). During the rainy season of 2006 in the Soconusco Region of Chiapas, Mexico, passerine birds were mist-netted in four habitats of a coffee agroecosystem representing different levels of the agricultural intensification gradient. Indices of body condition were recorded for captured birds and ectoparasites were sampled using standard feather dusting methodology. Results indicate that agricultural management does affect parasite load, but that this relationship may depend on host-parasite interactions and host life-history traits. For all birds, higher lice prevalence was found among hosts in the most intensified system, while higher mite prevalence was found in the least intensified system. Patterns in prevalence across the habitats were also different for reproductive male and female birds. For all birds, parasite intensity was highest in the most intensified system, but showed no difference in other habitats, suggesting a threshold response to intensification. Adult birds showed no changes in body condition across the habitats, but hatchyear birds had significantly lower body condition in the forest fragment, suggesting greater sensitivity to habitat changes and perhaps fragment size. Finally, different body condition indices exhibit opposing patterns relating host body condition and lice load intensity.