Subfossil diatoms from Lago Nahuel Huapi (Brazo Blest), Argentina.

Abstract

Anatomy and morphogenesis of galls produced by Leptocybe invasa in plants of Eucalyptus. Leptocybe invasa is a gall-inducing wasp that oviposits in the young eucalyptus leaves. The plant responds by forming a gall. As a result, this not only causes rolling leaves and defoliation, but also collapses the tree buds which affect seriously the eucalyptus production. In this paper, it is analyzed the morphogenetic and anatomical changes that are caused by the development of galls and then it is compared with healthy plants. The Eucalyptus grandis and Eucalyptus camaldulensis are cultivated in Corrientes, Argentina, and have been studied with traditional techniques of optical and scanning electron microscopy. The wasp oviposits among the vascular bundles, and the plant produces an hyperplastic tissue that are differed into four layers: nutrient, tanniniferous, sclerotic, and crystalliferous. The circulation of the vascular tissues is obstructed and consequently it is interrupted the normal flow of water and solutes that are transported in the xylem. Hence, this situation produces circular vessel. In fact, it is not only analyzed the morphological and anatomical changes but also the insect development, and this cycle is divided into three stages. This work demonstrates that the formation of galls in the eucalyptus are an excellent example of extended phenotype, where the action of L.invasa induces the abnormal growth of plant tissues because of the increase the number of cells, the collapse of the vascular system of the affected area and the apparition of new anatomical features