Galhas de Calophya aff. duvauae Scott (Hemiptera: Calophyidae) em Schinus polygamus (Cav.) Cabrera (Anacardiaceae): alterações químicas e estruturais e interações com parasitoides e inquilinos

Abstract

Insect galls are structures composed of different plant tissues that provide shelter, protection and nourishment to the inductor and their descendants. The relationship between host plant and gall inducer is usually species-specific, with each gall morphotype being related to a single galling insect. However, a host plant can respond to different insect stimuli, as it is found in so-called super-host, or it may present variations in these structures in response to the action of an inquiline. Schinus polygamus (Cav.) Cabrera (Anacardiaceae) is a super-host of galling herbivores, among which Calophya aff. duvauae Scott stands out by inducing leaf galls whose color varies from red to green in the adaxial surface. These galls may have a Hymenoptera sp. 1 (H1) endoparasitoid and two associated inquilines, a Hymenoptera sp. 2 (H2) and Lepidoptera sp. (LP). Samples were collected quarterly, between June 2008 and March 2009, in a population in the city of Canguçu, Rio Grande do Sul, Brazil. Most galls occurred in the median part of the leaf, with a predominance of red galls in relation to the green ones. The red color is presumably due to the constant stimulus of the healthy gall inducer since the rate of malformed gallers inside green gall was high. There is a notable reduction in the content of photosynthetic and photoprotective pigments in the galls when compared to ungalled leaves, especially for total anthocyanins of the green galls. The induction occurs preferentially in young leaves, but it may also take place in mature leaves with the redifferentiation of the tissues. The mature gall is characterized by the homogenization of the parenchyma, neo-formed vascular bundles, hypertrophy and hyperplasia of the tissues and absence of nutritive tissue and lignification, features which are related to feeding habit of the sucking calophyd. The presence of H1 did not cause any anatomic changes or, alternatively, induced the growth of isolated nutritious cells inside the nymph chamber. H2 induces the formation of abundant nutritive tissue, while LP does not cause tissue damage besides the vestiges of its feeding activity in epidermal cells of the nymphal chamber. Galls containing the inducer, H1 or H2 induced changes in the allocation of substances from primary and secondary metabolism, but did not cause or suppress the synthesis of these compounds.