Reações estruturais e químicas de caryocar brasiliense camb. (caryocaraceae) a herbívoros galhadores

Abstract

Caryocar brasiliense Camb. (Caryocaraceae) has hairy leaves, which constitute a physical barrier that the galling insect, Eurytoma sp. can surpass and get success in oviposition. Anatomical studies aimed to answer how the oviposition and feeding patterns of the galling insect alter the morphogenesis of the host plant. The gall of C. brasiliense is hairy, globular and prominent to leaf abaxial surface. It develops preferentially next to leaf margin, and the larval chamber contains a single larvae. Due to the formation of the galls, alterations are observed in the three plant tissue systems, following a pattern referred in literature for Hymenopteran galls. Gall development may cause changes in plant development, as observed in several galling insect-host plant systems. It is believed that these changes are the result of the reallocation of resources to the site of formation of galls. To study the impact of gall induction on the leaves of Caryocar brasiliense Camb., the level of infestation, the effects on leaf area, the content of photosynthetic pigments, and the histochemical detection of primary and secondary metabolites were analyzed. The level of infestation was considered medium, in comparison to other systems. Leaf area was significantly larger on galled leaves which may indicate that leaf expanded due to a sink formed towards gall site or the potentially resumption of the marginal meristem, depending on the age of the leaves at the time of induction. Although the galls have presented reduced photosynthetic pigments contents in relation to healthy tissue, the increase in leaf area may indicate compensatory mechanisms or the establishment of a sink from the photosynthetically active plant parts towards the gall. The accumulation of phenolic substances in peripheral tissues of the galls of C. brasiliense may represent a defense against natural enemies of the galling insect, while the absence or reduced content of these compounds in the feeding site of the larvae may favor its establishment. The detection of reducing sugars in the nutritive tissue of these galls reveals a king of nutritious reserve not previously reported for Hymenoptera induced galls.