Sun and shade galls of Clinodiplosis profusa (Cecidomyiidae) on Eugenia uniflora (Myrtaceae): Are there differences in their establishment and growth?

Abstract

Gall-inducing insects stimulate their host plants, leading to the formation of distinct structures, such as the fusiform galls induced by Clinodiplosis profusa Maia, 2001 (Cecidomyiidae) on leaves of Eugenia uniflora L. (Myrtaceae). The influence of different light conditions on infestation rates, establishment, and morphogenesis of galls is little known. We tested if gall infestation is higher in E. uniflora sun plants compared to shade plants, and if the size, anatomical, and histometrical features of the mesophyll and epidermis are distinct between sun and shade leaves and galls. Gall infestation rates are similar in sun and shade plants, although the results indicate a possible difference in life cycle duration between the light conditions. Anatomical data revealed the leaves and galls respond similarly to sun and shade for number of cell layers. In the galls the hyperplasia provoked by C. profusa is influenced by distinct sunlight exposure. Cell hypertrophy and a reduced stomatal index in the galls is remarkable when compared to non-galled leaves. The cell sizes in the mesophyll and epidermis and stomatal densities are similar between the sun and shade galls, but these factors are distinct between the sun and shade leaves. Cell hypertrophy and epidermal differentiation patterns are more influenced by the gall inducer, which inhibits the influence of light on these patterns. In conclusion, gall morphogenesis is strongly influenced by galling stimuli for some developmental processes, but other processes are influenced by abiotic conditions, such as light exposure. This opens a field in gall ecological anatomy and development.