Occurrence and characterization of entomogenic galls in an area of Cerrado sensu stricto and Gallery forest of the state of Bahia, Brazil

Abstract

We surveyed insect galls in an area of Cerrado sensu stricto and Gallery forest in the municipality of Caetité (BA) to contribute to current knowledge of the local flora and its associated gall-inducing insects. Monthly collections were made between February/2015 and January/2016, totaling 12 field campaigns (involving two or three people and lasting four hours) that followed an established path through the countryside. A total of 63 gall morphotypes were identified on 47 host plant species belonging to 22 families; 17 morphotypes were found in the Gallery forest and 46 in Cerrado vegetation. The plant families showing the greatest gall richness were Leguminosae (n=15), Myrtaceae (n=9), and Asteraceae (n=7). The species with the greatest number of galls was Mimosa gemmulata Barneby (Leguminosae) (n=3). Most galls were observed on leaves (66%) and stems (24%); they were mostly green (49.3%) or brown (26%), with globoid shapes (39.7%) or marginal roll (17.4%), and were unilocular (87%), glabrous (62%) and isolated (89%). Cecidomyiidae (Diptera) were the principal gall-inducing insects. The associated fauna was principally composed of Hymenoptera. Eight plant taxa were recorded for the first time as hosts of galling fauna.

Insect galls and their host plants in gallery forest in Bahia State, Brazil

“…The richness of galling insects in the study area was greater than that found in other inventories of gallery forests in Brazil (Urso-Guimarães et al 2003;Araújo et al 2011;Silva et al 2018; . The reasons for the variation in the number of gall morphotypes can be explained by size and richest plant families of the studied area, or it could also be a sampling artifact including the differences in the sampling type (fixed transects or random walks), collection effort (sampling duration and number of collector), and sampled host plants (all plants or only herbs, shrubs or trees) (Bergamini et al 2017).…”

“…The reasons for the variation in the number of gall morphotypes can be explained by size and richest plant families of the studied area, or it could also be a sampling artifact including the differences in the sampling type (fixed transects or random walks), collection effort (sampling duration and number of collector), and sampled host plants (all plants or only herbs, shrubs or trees) (Bergamini et al 2017). In our survey, the plant families richest in gall morphotypes were Leguminosae and Myrtaceae, similar to the other gall inventory in gallery forest in Bahia State, Brazil (Silva et al 2018). The results corroborate the hypothesis that families with the highest number of plant species have proportionally the highest number of gall-forming species (Fernandes 1992;Mendonça 2007).…”

“…The results corroborate the hypothesis that families with the highest number of plant species have proportionally the highest number of gall-forming species (Fernandes 1992;Mendonça 2007). Leguminosae is one of the main host families of galls in different Brazilian habitats (Araújo et al 2019, Santos-Silva and Araújo in press) such as caatinga (e.g., Carvalho-Fernandes et al 2012;Brito et al 2018), cerrado (Coelho et al 2009;Silva et al 2018;Vieira et al 2018), caatinga-cerrado transition areas (Costa et al 2014a, b;Nogueira et al 2016), and restinga (Maia et al 2008;Maia and Oliveira 2010). Myrtaceae also plays an important role in gall inventories conducted in Brazil (Maia 2013a(Maia ,b, 2014Maia and Souza 2013).…”

“…Hymenaea martiana Hayne (n = 4) 30 1.5 Myrtaceae (n = 4) Jacaraci trail, Caetité, BA (Silva et al 2018) Meliaceae (n = 3) -Guarea sp. (n = 3) 17 1.2 Myrtaceae (n = 3) Silvânia, GO (Bergamini et al 2017) Burseraceae (n = 14) Siparunaceae (n = 11) Celastraceae (n = 10) Leguminosae Myrtaceae (n = 7)…”

“…Studies of gall richness in gallery forests have been rare in Brazil, and they were initiated only in the early 2000s (Urso-Guimarães et al 2003;Araújo et al 2011;Luz et al 2012;Bergamini et al 2017). That situation is no different in gallery forests in Northeastern Brazil; only one study has yet been undertaken in Bahia (Silva et al 2018). Considering the high species-specificity of these galling insects to their host plants and the endemism of the host plants, one would expect high richness of galls in gallery forests.…”