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

ROSSETTI, M. R.; GONZÁLEZ, E.; SALVO, A.; VALLADARES, G. R.

ARTHROPOD-PLANT INTERACTIONS

SPRINGER

Lugar: Berlin; Año: 2014

1872-8855

Habitat fragmentation can disrupt ecological process such as herbivory and alter interactions 33 between different levels of a community like insect herbivory. Few studies have examined which changes 34 in plant traits and natural enemies drive changes in herbivory, and differences among insect guilds in this 35 context have been largely ignored. Here, we studied area and edge effects on herbivory by three guilds of 36 phytophagous insects in a fragmented Chaco Serrano forest. We estimated herbivory levels through leaf 37 collection on native Croton lachnostachyus plants, and assessed plant availability (distance to the nearest 38 conspecific) and quality indicators (leaf content of water, carbon and nitrogen), as well as richness and 39 abundance of the associated insect community, in order to explore mechanisms that may drive herbivory 40 changes. Herbivory by chewing and sap-sucking insects increased in plants from the forest interior 41 compared with those at the edge, whereas forest area effects were detected only in interaction with edge 42 effects on chewing and total herbivory. The increase at the edge appeared to be driven mainly by changes 43 in leaf water and nitrogen content for sap-sucking herbivory. However, this explanation did not apply to 44 chewing damage which was independent of any of the studied factors, whereas plant availability was 45 linked to leafminer herbivory levels. Total herbivory was slightly associated to water content and not by 46 changes in the insect community. These results emphasize the necessity to consider differential responses 47 from diverse phytophagous insect guilds and factors operating at multiple levels in order to disentangle 48 and ultimately understand forest fragmentation effects on herbivory.