Soils and seasonality influence the richness of gall-inducing insects and their host plants in a tropical dry forest

Abstract

The richness of specialized herbivores and their host plants in a Brazilian dry forest was inventoried to evaluate if soil types and seasonality are important factors determining the composition of gall-inducing insects and their host plants in Caatinga environments on a local scale. This study recorded 12 different morphotypes of gall distributed among eight host species belonging to five botanical families. Both soils and seasonality influenced the number of species and individuals of host plant, and the richness of gall-inducing insect. The greatest richness of gall-inducing insects and their host plants was observed during the rainy season in the Caatinga vegetation on soils of sedimentary origin, which is considered to have low fertility as regards phosphorus content. Our results corroborate the hypothesis of soil fertility which predicts that the richness of gall-inducing insects will be higher on infertile soils and demonstrate the importance of substrate and seasonality for the richness of gall-inducing insects in Caatinga on a local scale.