Occurrence and characterization of insect galls in two areas of tropical dry forest (caatinga) in São Francisco River Natural Monument, Brazil

Abstract

The caatinga vegetation is an important natural laboratory for the study of how plants and gall-inducing insects interact in highly variable and stressful moisture regimes. Despite this, only five gall inventories have been conducted and its richness of inducing insects and host plants has been little known. To contribute to our knowledge of galls from caatinga habitats, we registered and characterized the macroscopic aspects of the galls, then identifed the plant hosts and their associated fauna in two areas of caatinga in São Francisco River Natural Monument (MONA). Nineteen morphotypes of galls were recorded on 11 plant belonging to eight genera and six host plant families. Of the total number of galls recorded, most occurred in the rainy season (n=13). Most of the galls are globoid (n=10), pilose (n=10), green (n=15), and isolated (n=12). Most of the gall-inducing insect species found belonged to Diptera (Cecidomyiidae). All morphotypes recorded in this study are the first ones recorded of galls and their host plants in MONA. We also recorded, for the first time, the occurrence of galls in the floral buds of Cnidoscolus obtusifolius Pohl ex Baill. (Euphorbiaceae), demonstrating the importance of conducting studies in areas not yet sampled in the Caatinga biome. It is expected that this study will stimulate future investigations, helping in the protection and conservation of this conservation area and consequently increasing our knowledge about its biodiversity.