Abstract

The success of galling insects could be determinate by synchronization with host plant phenology and climatic conditions, ensuring suitable oviposition sites for gall induction, as well as food resources for their survivorship. Galling insects induce anatomical and metabolic changes in host plant tissues, ensuring gall development. Calophya rubra Blanchard (Hemiptera: Psylloidea) induces conical galls on the stems of Schinus polygamus (Cav.) Cabrera (Anacardiaceae), an evergreen plant, during late spring. In Chile, C. rubra was previously described as a bivoltine species. However, ours results showed that the climatic conditions of the Mediterranean Region, limit C. rubra nymphs’ activity during unfavorable periods, and determine a diapause period and a univoltine life cycle. The establishment of insect in the cortical parenchyma of young stem, trigger hypertrophy and hyperplasia around the feeding site of the nymph, followed by proliferation of the epidermal and outer cortical cells whit trichomes in the ostiolar opening and vascular units differentiated within gall middle parenchyma. Based on a quantitative analysis the conical stem gall traits imply in gains over the stem, but the absence of alterations in the phellem, secretory ducts and pith are indicative of traits that insect cannot manipulate. Another peculiarity of the gall cells is the non-lignification of the perivascular fibers and secondary xylem, and overpotentialization of lipid and phenol synthesis pathways. The stem gall on S. polygamus combines the stimuli of C. rubra and the morphogenetic constraints of the host stems toward insect nutrition, maintenance and protection. Phenological, anatomical and histochemical features of conical stem gall occur distinctly in Mediterranean populations of C. rubra, indicating an adjustment of the insect life cycle with reactive sites of its host plants and to macroclimate conditions.