Ecosystem services across the landscape: the case of insect parasitism in the Chaco ecosystem, NW Argentina

MONMANY, A. CAROLINA; YU, MEI.; ZIMMERMAN, J.

San Juan

Encuentro; First undergraduate and graduate student meeting of research of the University of Puerto Rico,; 2012

Universidad de Puerto Rico

Parasitoid wasps and flies are specialized predators that kill caterpillars using myriad strategies. Parasitoids are an understudied but key component of biodiversity because they strongly regulate herbivory and biodiversity of moth and butterfly through interactions at previously undefined landscape levels. This regulation is considered a valuable ?free? ecosystem service and what mediates parasitism patterns has been a largely explored question in conservation and pest management. Landscape complexity has been shown to influence parasitism but the mechanism is unclear. I examined how moth and butterfly parasitism was modified in relation to landscape complexity in the Chaco, Argentina. I calculated landscape complexity from a high resolution (0.60 m) QuickBird satellite image (2007) of the study region. In the field I collected around 3,000 caterpillars in 20 1-ha plots representing different landscape complexities. The caterpillars were reared in the lab until adult host or parasitoid emergence to determine parasitism (number of parasitized hosts /total captured hosts) per plot. Parasitism ranged from 0% to 19%. Higher parasitism was observed in agricultural or mixed agricultural-forest plots and lower parasitism was observed in forested plots. This result is in accordance to previous studies where generalist parasitoids were favored by agricultural fields surrounded by a similar land cover. Our results can help understand how an ecosystem service such as pest control may be enhanced through appropriate landscape design.