Anatomia de galhas de ambrosia em folhas de Baccharis concinna e Baccharis dracunculifolia (Asteraceae)

Abstract

-(Anatomy of ambrosia leaf galls in Baccharis concinna and Baccharis dracunculifolia (Asteraceae)). Ambrosia galls are induced by dipteran (Cecidomyiidae) and no nutritive tissue is present: fungi hyphae are the source of food to the inducer larva. Ambrosia galls in Baccharis concinna and B. dracunculifolia have only one chamber with one inducer. The fungi hyphae are observed. In B. dracunculifolia galls the hyphae are restricted to the larval chamber. The parenchyma palisade cells are elongated. In B. concinna galls hyphae spread also among chlorenchyma cells around of larval chamber. The chlorenchyma cells near to the chamber elongate slightly. In both galls, pericyclic fibers of vascular system lose their secondary walls. When the inducer is in pupal phase, the amount of hyphae increases and they fill several parts of the larval chamber. Hyphae of B. concinna galls present lipophilic globules which are not observed in the hyphae of B. dracunculifolia galls. Picnids are found only in the senescent galls of B. dracunculifolia. This paper is the first contribution to the knowledge of the ambrosia galls in the Brazilian flora.RESUMO -(Anatomia de galhas de ambrosia em folhas de Baccharis concinna e Baccharis dracunculifolia (Asteraceae)). Galhas de ambrosia são induzidas por dípteros (Cecidomyiidae) e desprovidas de tecido nutritivo, pois a larva do indutor alimenta-se de hifas de fungos. As galhas de ambrosia de Baccharis concinna e B. dracunculifolia são constituídas por uma única câmara larval, contendo um indutor. São observadas hifas de fungos. Nas galhas de B. dracunculifolia, as hifas ficam confinadas à câmara larval e as células do parênquima paliçádico mostram-se alongadas. Nas galhas de B. concinna, as hifas estão presentes também entre as células do clorênquima situadas ao redor da câmara larval. As células do clorênquima próximas à câmara larval alongam-se ligeiramente. As fibras pericíclicas do sistema vascular, em ambas as galhas, perdem as paredes secundárias. Quando o indutor está em fase pupal, as hifas de fungos aumentam em quantidade e preenchem várias partes da câmara larval. Nas hifas da galha de B. concinna verifica-se a presença de glóbulos lipofílicos, que estão ausentes nas hifas das galhas de B. dracunculifolia. Picnídios são observados somente nas galhas senescentes de B. dracunculifolia. Este trabalho é a primeira contribuição ao conhecimento de galhas de ambrosia na flora brasileira.

Anatomy and ontogenesis of hymenopteran leaf galls of Struthanthus vulgaris Mart. (Loranthaceae)

“…Secondary walls of xylem elements, which are enclosed by pericyclic fibers, do not disintegrate. Similar effects were observed in the leaf gall induced by the cecidomyiid (Arduin et al 1991), but they seem not to be peculiar to S. vulgaris galls, as they occur in other plant galls (Arduin & Kraus 1995, 2001, Souza et al 2000. The pericycle is a tissue that retains its meristematic capacity, so the dedifferentiation of their cells simultaneously with the process of delignification is easily comprehended.…”

Anatomical and developmental aspects of leaf galls induced by Schizomyia macrocapillata Maia (Diptera: Cecidomyiidae) on Bauhinia brevipes Vogel (Fabaceae)

“…However, fungi hyphae were in direct contact to the covering layer as described for ambrosia galls induced on B. dracunculifolia DC. and B. concinna (Arduin & Kraus 2001). At the last phase, the senescence, the covering layer cells present phenolic contents (data not show), similarly to a gall induced by an undescribed Cecidomyiidae species on Tabebuia ochracea (Cham.)…”

“…Moreover, galls induced by S. macrocapillata lack secondary xylem cells and periciclic fibers. The non differentiation of these lignified cells was also observed in the ambrosia galls induced by an unidentified species of Cecidomyiidae on leaves of Baccharis concinna (Arduin & Kraus 2001), and may indicate that the energy otherwise used to differentiate lignified cells is deviated to other gall requirements. Indeed, the exclusively phloematic bundles indicate the establishment of a drain of photosynthates to gall tissues (Rohfritsch 1992).…”

“…(Meliaceae) the spongy parenchyma cells also divide and become rounded with small intercellular spaces (Kraus et al 1996). Regarding the vascular system, gall formation on the leaves of Baccharis concinna G. M. Barroso (Asteraceae) causes alterations in periciclic fibers, which loose their ordinary secondary walls noticed in healthy leaves (Arduin & Kraus 2001). …”

“…This type of gall is rarely reported in the tropics and is assumed to be a type of mutualism as larval survival depends on the adult female collecting the fungus and depositing it along with the eggs in the attacked organ of the host plant (Rohfritsch 2008). Although many progresses on the anatomy of Cynipidae-and Cecidomyiidae-induced galls has been achieved (Bronner 1992, Rohfritsch 1992, Brooks & Shorthouse 1998, Rohfritsch 2008, to date, only one study on the anatomy of an ambrosia leaf gall has been conducted in the Brazilian flora (Arduin & Kraus 2001). Moreover, to our knowledge no Neotropical study has reported on ambrosia gall development from egg deposition to gall maturation.…”