Diversity patterns of host plants and their gall-inducing insects in the Brazilian Cerrado: testing ecological and historical hypotheses

Cerrado is one of the most diverse savannahs on the planet in terms of plant species and insect herbivores, as well as in hotspot in the diversity of plant–galling insect interactions. The aims of the study were as follows: characterize the diversity of host plants (HP) and their associated gall-inducing insects (GII) in the Brazilian Cerrado; estimate the species richness of GII for the Cerrado vegetation; determine if GII species richness is shaping the plant species richness, taxa size, and the taxon age; to analyze the number of species per HP communities, and estimate the number of GII (co-threatened) in endangered plants. We used a comprehensive database compiling information available in 32 inventories on GII and their HP from several areas of the Cerrado. We find 994 morphospecies associated with 505 HP. Additionally, we estimated a total of 11,745 GII for the Cerrado, of which 8,574 were cecidomyiid species. More than 58% of the HP harbored a single GII, while 42% had more than two GII, corroborating the high specialization of the GII on their HP. Finally, we detected nine threatened HP hosting 27 species of GII, which are considered super-hosts. Our study is the first to analyze the assemblages of HP and their GII in the Cerrado vegetation at a regional scale. Our findings indicate a high regional diversity of both HP and GII, and we highlight the importance of plant species richness, taxon size, and the taxon age as factors shaping the diversity of GII in the Cerrado.