Change in herbivore insect communities from adjacent habitats in a transitional region

Ecotonal areas between habitats vary in floristic composition and phenological patterns of the vegetation. In these regions, the habitat structure and plant phenology potentially affect the diversity of associated herbivore insects guilds (chewing and sap-sucking). In this study, the following hypotheses were tested in three habitats (cerrado sensu strictu, dry forest and riparian forest) in a Cerrado–Caatinga transitional area: (1) There is a variation in composition, richness and abundance of herbivore insects associated with the canopy among adjacent habitats; (2) habitats with higher variation in canopy cover support lower richness and abundance of herbivore insects; (3) habitats with more tree species and higher tree density support higher richness and abundance of herbivore insects; and (4) differences in species composition of herbivore insects among adjacent habitats are the main source of diversity in transitional habitats. The community of herbivore insects differed among the habitats, being similar between riparian and dry forests and different from cerrado. Canopy cover variation, richness and density of trees did not influence richness and abundance of chewing herbivores. A negative effect of canopy cover variation was observed in richness and abundance of sap-sucking herbivore insects, and a negative effect of tree density was observed on abundance of sap-sucking herbivore insects. A higher importance of beta diversity among habitats was observed if compared to beta diversity within habitats (54 %). This study points out that strategies of conservation must consider the entire vegetation mosaics to protect a higher number of species, and to keep these regions with high diversity.