Gall responses to drying habitats: insights from the communityof galling herbivores associated with the superhost Caryocar brasiliense Cambess. (Caryocaraceae)

Abstract

Galls are new plant organs formed in response to the stimuli of gall-inducing organ-isms, but may also be influenced by environmental conditions.• This study evaluated the richness, abundance, and co-occurrence in the gall commu-nity associated with Caryocar brasiliense Cambess. (Caryocaraceae) areas with varyingdegrees of environmental stress due to the drying of palm swamps, called Veredas.Additionally, structural and metabolic attributes related to nutrition and protectionwere evaluated as possible stress markers. The research was conducted in two Cerradoareas with different water availability: the Parque Estadual Veredas do Peruacßu (lowerwater availability; more stressful) and the Area de Protecß~ao Ambiental do Rio Pandeiros(higher water availability; less stressful).• A total of 51,336 galls from five morphospecies were sampled: intralaminar globoid gall(IGG), extralaminar globoid gall (EGG), globoid petiolar gall (GPG), lenticular gall(LG) and clavate gall (CG). Gall richness was similar in both environments, but abun-dance was higher in the less stressful area, challenging the hypothesis that environmen-tal stress increases gall formation. Random co-occurrence patterns suggested that gallinducers occupy distinct spatial niches to reduce competition. Structurally and meta-bolically, galls exhibited similarities, including nutritive tissues and nutritious sub-stances in their internal compartments. However, in the more stressful environment,some galls had smaller internal and larger external compartments, with increased lig-nin and phenolic compounds in the outer tissue layers.• Lignin deposition and phenolic accumulation are evidenced as stress markers whichindicate that galls display phenotypic plasticity and adaptive strategies, enhancing pro-tection and survival under the stressful conditions of drying environments.