Lasioptera rubi , a Pest of Rubus idaeus : Galls Morphology, Anatomy and Histochemistry

Rubus species are affected by the gall inducer Lasioptera rubi (Diptera, Cecidomyiidae), which produces galls predominantly on the stem but sometimes also on the petiole. The presence of these neo-structures at the stem level can affect their survival and implicit production in raspberry crops. The purpose of the present study is to achieve the first detailed description of the histological and morphological peculiarities of these galls, which present great variability from these points of view. Three morphotypes were described in the galls produced in the stem, depending on the position of the larval chambers and the degree of damage to the vascular system. The histochemical investigations highlighted the presence of reducing sugars and proteins as the main nutrients in the gall tissues, as well as the presence of polyphenols and terpenoids as secondary products of metabolism. Indoleacetic acid was identified near the larval chambers and in the neighboring tissues, its presence having an important role in the changes in the morphogenesis of the secondary xylem in the stem and in inducing the appearance of meristematic nodules in the gall structure.