Specialized herbivores have differential distribution in veredas under different drying levels

Abstract

AbstractWe investigated the distribution patterns of galling insects in veredas with varying degrees of drying in the Brazilian Cerrado. We tested if the insect gall diversity is higher in degraded veredas (dry veredas) compared to preserved (wet veredas) ones, as predicted by the hygrothermal stress hypothesis. Additionally, we also tested whether the composition of galling insects varied along the veredas and if species richness and abundance of galling insects are higher in the upstream zone of the veredas. In total, we recorded 99 species of galling insects, distributed across 54 plant species and 24 botanical families. We found that galling species richness was high in degraded veredas compared to preserved ones, while the abundance of galling insects was higher in preserved veredas than in degraded ones. When examining the different zones along the veredas, we observed variations in the richness and abundance of galling insects in preserved veredas. Specifically, the galling insect richness was higher in the upstream and middle zones compared to the downstream zone, while the abundance of galling insects was higher in the middle zone compared to the upstream zone. However, in the degraded veredas, there were no significant differences in galling species richness and abundance among the zones studied. The composition of galling insect species differed significantly between degraded and preserved veredas, with a higher faunal similarity observed in preserved veredas for both the downstream and upstream zones compared to degraded veredas (upstream zone). Our results indicate a preference of galling insects for more hygrothermally stressed environments, such as dry veredas and upstream zones of wet veredas.