Abstract

• Some chewing larvae are capable of inducing galls in the vascular cylinder, such as Dasineura sp. (Cecidomyiidae) on Peumus boldus stems. Due to the medicinal and economic importance of P. boldus, the anatomical and functional implications of the establishment of Dasineura sp. on its stems have been investigated. The hypothesis proposed is that the establishment of Dasineura sp. in the P. boldus stem induces abnormalities at the cellular and organizational level of the vascular system that increase along gall development, to favor the hydric status of the gall. • Anatomical alterations induced in the stems along gall development were determined. Cytohistometric analyses in mature galls were compared to non-galled stems, and the water potential and leaf area of non-galled stems were compared with galled stems. • Dasineura sp. establishes in the vascular cambium, producing delignification and rupture of xylem cells and inhibiting the formation of phloem and perivascular sclerenchyma. In response to the larval feeding stimulus, the vascular cambium produces differentiation of vascular parenchyma and sclerenchyma cells, and vessel element dimension modifications. Gall diameter increases together with larval feeding activity, producing a large larval chamber and numerous layers of nutritive tissue, vascular parenchyma, and sclerenchyma. The anatomical alterations do not affect galled stems’ leaf area, but favor greater water flow towards these stems. • The anatomical alterations induced by Dasineura sp. in P. boldus stems guarantee water and nutrient supplies to the gall and larva. After the inducer exits, the branches die due to vascular disconnection with the plant body.