Herbivore-parasitoid body sizes in the landscape.

MONMANY, A. CAROLINA; RESTREPO, C.

SAN JUAN

Congreso; 42nd Junior Technical Meeting/27th PRISM.; 2007

Interamerican University at Bayamón,

Habitat fragmentation influences interactions among organisms, with likely consequences for the structure and function of biotic assemblages. Departing from the traditional approach on species diversity and abundance patterns, we focus on body size of herbivores and parasitoids to explore the consequences of habitat fragmentation on the structure and function of species assemblages. Specifically we ask (1) how does habitat fragmentation affect herbivore and parasitoid body size? And (2) how does body size of herbivores and parasitoids influence parasitism patterns? To answer these questions, we collected and reared Lepidoptera larvae and parasitoid adults from 11 forest fragments and two continuous forests in the Yungas-Chaco ecotone, NW Argentina. We measured forward wing length of 465 adult Lepidoptera belonging to 80 morphospecies, and body length of 125 parasitoids from 47 morphospecies. We found that body sizes varied in the order of 10 in both Lepidoptera and parasitoids. Body sizes were best characterized by multimodal distributions in which the modes suggested functional groups. Moreover, body size distributions varied in fragmented landscapes due to changes in population sizes and/or functional groups. Some of these groups were constant under different degrees of fragmentation, an indicative of functional robustness. There was a significant relationship between herbivore and parasitoid morphospecies body size and fragmentation modified patterns of parasitism related to herbivore body sizes. Our exploratory results suggest that the analysis of body size patterns in fragmented habitats may yield new information on the response of biotic assemblages to fragmentation. Analyzing changes in body size patterns due to fragmentation may help us understand the link between structure and function in species assemblages.