Insect galls of the Chapada Diamantina, Rio de Contas, Bahia, Brazil

Abstract

We surveyed insect galls and their host plants in areas of Caatinga and Cerrado in the municipality of Rio de Contas, in the extreme south of the Chapada Diamantina (Bahia state), between 703 and 1,897 m altitude, in order to contribute to the knowledge and conservation of local biodiversity. The survey was conducted in eight locations, adopting the random walking methodology for sampling, four in Caatinga and four in Cerrado, covering distinct phytophysiognomies (cerrado sensu stricto, gallery forest, shrubby caatinga, riparian forest, and rocky field). Eighty-four different insect gall morphotypes were reported, 48 (57.14%) of them on 42 host species in Cerrado and 36 (42.86%) on 24 host species in Caatinga. Most galls occurred on leaves (48.72%) and were globoid (53.76%), glabrous (52.92%), isolated (55.44%), usually one-chambered (61.32%), and brown (25.2%). The gall-inducing insects identified belonged to Lepidoptera (n = 1), Thysanoptera (n = 1), Hemiptera (n = 2), and Diptera (Cecidomyiidae) (n = 16). This was the first inventory of galls in the Chapada Diamantina, so all records are new for the region. We also recorded the first occurrences of galls on two Cerrado plant species and on two in the Caatinga. We found a significant positive correlation between gall richness and plant species richness, suggesting that radiation of gall-inducing insects may be associated with plant species richness.

Keywords:
Cecidomyiidae; Fabaceae; Gall-inducing insect; Host plant; Semi-arid