GALLS ON Sapium glandulosum (Euphorbiaceae) INDUCED BY Neolithus faciastus (Hemiptera: Triozidae) IN A MULTITROPHIC CONTEXT: STRUCTURAL, HISTOCHEMICAL AND IMMUNOCYTOCHEMICAL CHANGES INDUCED BY THE INQUILINE

Abstract

Inquilines interact with the gall, feeding on its tissues and modifying it structurally and chemically. We selected globoid leaf galls induced by Neolithus faciastus on Sapium glandulosum, with the inquiline Eurytoma sp. In this work, we evaluated the anatomical, micromorphometric, histochemical and immunocytochemical modifications of the cell wall promoted in the galls after the entry of the inquiline, in the larval, pupa and adult stages. The presence of the inquiline leads to subtle histochemical changes in the galls, such as the apparent remobilization of some primary metabolites, such as starch, and the loss of secondary metabolites, such as alkaloids. The deposition of compounds on the cell wall changed especially in galls with inquiline larvae, forming a centrifugal gradient of compound labeling on the cell wall. Non-methylesterified HGs and extensins in the cortex of gall larvae and pupae increased the structural reinforcement of cell walls, which may be related to the physical pressure caused by the number of inquilines in the gall. (1 → 4)-β-D-galactans, (1 → 5) α-L-arabinans, extensins and RG-1 in the vascular bundles of inquiline galls may have ensured the flexibility and adhesion of their cell walls, necessary to support the high flow of metabolites provided by the remobilization of reserves. Herein, we demonstrate that Eurytoma sp. stimulated the tissues of the leaf galls of S. glandulosum, changing histological patterns to the composition of non-cellulosic compounds in the cell wall.