Not all in the same boat: Trends and mechanisms in herbivory responses to forest fragmentation differ among insect guilds

MARÍA ROSA ROSSETTI; EZEQUIEL GONZÁLEZ; ADRIANA SALVO; GRACIELA VALLADARES

ARTHROPOD-PLANT INTERACTIONS

SPRINGER

Año: 2014 vol. 8 p. 593 - 603

1872-8855

Habitat fragmentation can disrupt ecological process such as herbivory and alter interactions between different levels of a community like insect herbivory. Few studies have examined which changes in plant traits and natural enemies drive changes in herbivory, and differences among insect guilds in this context have been largely ignored. Here, we studied area and edge effects on herbivory by three guilds of phytophagous insects in a fragmented Chaco Serrano forest. We estimated herbivory levels through leaf collection on native Croton lachnostachyus plants, and assessed plant availability (distance to the nearest conspecific) and quality indicators (leaf content of water, carbon and nitrogen), as well as richness and abundance of the associated insect community, in order to explore mechanisms that may drive herbivory changes. Herbivory by chewing and sap-sucking insects increased in plants from the forest interior compared with those at the edge, whereas forest area effects were detected only in interaction with edge effects on chewing and total herbivory. The increase at the edge appeared to be driven mainly by changes in leaf water and nitrogen content for sap-sucking herbivory. However, this explanation did not apply to chewing damage which was independent of any of the studied factors, whereas plant availability was linked to leafminer herbivory levels. Total herbivory was slightly associated to water content and not by changes in the insect community. These results emphasize the necessity to consider differential responses from diverse phytophagous insect guilds and factors operating at multiple levels in order to disentangle and ultimately understand forest fragmentation effects on herbivory.