The influence of parasitoidism on the anatomical and histochemical profiles of the host leaves in a galling Lepidoptera – Bauhinia ungulata system

Galls induced by insects develop through a complex series of plant cell responses. Bauhinia ungulata L. (Fabaceae: Caesalpinioideae) has leaf-folding galls, which were studied by means of anatomical and histochemical approaches. These approaches compared the non-galled leaves, non-parasitoidized galls, and parasitoidized galls by addressing two questions: (1) what structural and histochemical changes are caused by the gall inducer in the leaf tissues of the host plant? And (2) is the parasitoid capable of affecting the gall structure? The non-galled leaf is amphistomatic, with anomocytic stomata, and multicellular non-glandular and navicular glandular trichomes. The mesophyll is dorsiventral, and the vascular system is surrounded by a lignified bundle sheath. In the gall, the outer epidermis is derived from the abaxial leaf epidermis. The outer cortex of the gall originates from the chlorophyllian parenchyma, and is homogeneous, with polyhedral cells and few intercellular spaces. The vascularization net is enhanced, and the secondary veins are disorganized. The nutritive tissue derives from the cells of the adaxial epidermis and adjacent parenchyma, which accumulate lipids, and is partly consumed by the chewing larvae. The cells of the outer cortex and those around the vascular bundles accumulate secondary metabolites, functioning as protective layers against natural enemies. The parasitoidized galls are similar to the non-parasitoidized ones, except for the sites of intact hyperplasic nutritive tissue with hypertrophied cells, which are visible macroscopically. This indicates the continued stimuli from the Lepidoptera feeding on the host-plant cells, which continue to enlarge, but will no longer be used for larvae nutrition.RESUMO: (Influência do parasitoidismo nos perfis anatômico e histoquímico das folhas em um sistema Lepidoptera galhador – Bauhinia ungulata) Galhas induzidas por insetos se desenvolvem por meio de uma série complexa de respostas celulares vegetais. Bauhinia ungulata L. (Fabaceae: Caesalpinioideae) apresenta galhas de dobramento foliar, aqui estudadas por meio de técnicas de anatomia e histoquímica, com o objetivo de comparar folhas não galhadas e galhas com e sem parasitoides, e responder as seguintes questões: (1) quais são as alterações estruturais e histoquímicas causadas pelo indutor nos tecidos da planta hospedeira? (2) O parasitoide é capaz de afetar a estrutura da galha? A folha não galhada é anfistomática, com estômatos anomocíticos, tricomas multicelulares não glandulares e glandulares naviculares. O mesofilo é dorsiventral, e o sistema vascular está envolvido por bainha lignificada. Na galha, a epiderme externa é derivada da epiderme abaxial; o córtex se origina do parênquima clorofiliano e é homogêneo, com células poliédricas e poucos espaços intercelulares. A vascularização é mais intensa e as nervuras secundárias se mostram desorganizadas. O tecido nutritivo, derivado de células da epiderme adaxial e do parênquima adjacente, apresenta células com conteúdo lipídico o qual é consumido em determinados pontos pela larva do indutor. O córtex externo e células ao redor do feixe vascular acumulam metabólitos secundários, funcionando como camadas protetoras contra inimigos naturais. As galhas com parasitoides são similares às sem parasitoides, exceto por apresentarem locais com tecido nutritivo intacto, hiperplásico, com células hipertrofiadas, os quais formam pontos visíveis macroscopicamente. Isso indica a manutenção do estímulo desencadeado pela larva nas células vegetais, que continuam sua expansão. Porém não mais servirão a sua função prévia de nutrição da larva

Anatomia floral de Epidendrum fulgens Brongn. (Orchidaceae - Epidendroideae) com ênfase no nectário e sua funcionalidade

Epidendrum fulgens Brongn. (Orchidaceae) possivelmente integra um sistema mimético floral juntamente com Asclepias curassavica L. e Lantana camara L. O estudo anatômico do nectário localizado na coluna de E. fulgens pode auxiliar no esclarecimento deste sistema. Nesta espécie, o nectário apresenta variações funcionais durante seu desenvolvimento. No botão floral, o revestimento é formado por epiderme simples com numerosos tricomas, nos quais os núcleos e nucléolos são conspícuos e o conteúdo citoplasmático é denso, sugerindo alta atividade metabólica e produção de secreção. Entretanto, quando a coluna completa sua formação, os tricomas apresentam-se menos numerosos, dispersos e sem indicativo de secreção. Apesar de não terem sido identificados compostos nutritivos na cavidade do nectário na flor madura, a presença de câmaras com insetos demonstra a possível atração química em alguma etapa do desenvolvimento floral

Social networks, language learning and language school student sojourners: a qualitative study

This thesis investigates individual language school student sojourners’ learning experiences in the UK. It takes into account the importance of learners learning through interaction with others in the target language community and recognises how learners’ social networks affect their language learning and use. There are many studies about students who study abroad for academic purposes and immigrant learners, but not many relating to individual language learners in private language schools. In order to fill this gap, this study focused on individual language school learners. With the intention of understanding how the social networks and language learning interact over time as part of their sojourner experience, I utilised different theoretical frameworks that have been applied to other groups of language learners and concluded that these frameworks are also applicable to private language school students. I recognised that in order to understand my participants’ learning experiences I needed to interact with them and also observe how they interacted with their social world. Therefore, formal interviews (semi-structured) and informal interviews (informal group meeting or chat) were the main methods for my study together with observation of interaction in various situations. This study identified the expectations that learners had with regard to the target language community, host families and native speakers’ attitudes towards foreign students, and the realisation that these expectations were higher than what was actually encountered. It also identified the steps the individual language learners took to overcome these disappointments and how they reconstructed their relationships with the target language and community respectively. In contrast with many previous studies which only focused on learning from native speakers, my study recognised that learners sometimes can have more interpersonal contact with their fellow students than native speakers. And consequently they benefit more from these contacts, in terms of language learning, than from native speakers. This thesis also helps language learners and language educators recognise basic theoretical frameworks which could help them evaluate the benefits and problems related to learning through interpersonal contact. And with this understanding learners will be able to facilitate their autonomous learning in the target language community

Potencialidades morfogênicas de Copaifera langsdorffii Desf. (Fabaceae): super-hospedeira de herbívoros galhadores

Copaifera langsdorffii Desf. é super-hospedeira de insetos galhadores, apresentando diferentes morfotipos de galhas em seus órgãos vegetativos. Galhas esféricas de gema e laminar, em taça e de nervura foram estudadas de modo a verificar o potencial morfogênico da planta hospedeira. Como um todo, observa-se que os três sistemas de tecidos da hospedeira são alterados pelos galhadores e fenótipos distintos são gerados. O sistema de revestimento mantém-se uniestratificado, com a exceção das galhas esféricas de gema, que apresentam revestimento suberificado, indicando espessamento secundário. O sistema fundamental é formado por parênquima homogêneo com esclereídes isoladas ou agrupadas. Galhas em taça apresentam lignificação em torno da câmara larval, importante na proteção contra inimigos naturais. Os quatro morfotipos apresentam cavidades secretoras de sesquiterpenóides, substâncias associadas à proteção química. O sistema vascular é formado por feixes de pequenas dimensões em todos os tipos de galhas. O número de câmaras larvais e de insetos por câmara variou, sendo indicativo de competição entre a prole. Os diferentes galhadores geram alterações divergentes nos sistemas de tecidos vegetais, revelando as amplas potencialidades morfogênicas da super-hospedeira C. langsdorffii

Ocorrência e estrutura de nectários extraflorais em Pterodon pubescens Benth. e em Pterodon polygalaeflorus Benth

Nectários extraflorais (NEFs) são estruturalmente variáveis e de ampla ocorrência entre as angiospermas. A ocorrência dos NEFs nas folhas de Pterodon polygalaeflorus Benth. e Pterodon pubescens Benth. (Fabaceae: Papilionoideae) foi detectada em espécimes adultas, durante a produção de novas gemas e flores. Os objetivos deste estudo foram registrar a ocorrência de NEFs em P. pubescens e P. polygalaeflorus, e fornecer dados comparativos sobre a estrutura anatômica destas estruturas. Os NEFs ocorrem na raque e estão localizados sob a inserção de cada peciólulo. Cada nectário consiste de uma pequena elevação cuja porção apical é fortemente invaginada, resultando em uma depressão (o pólo secretor), característica comum a ambas as espécies. Tricomas tectores unicelulares ocorrem ao longo da raque, sendo menos numerosos em P. polygalaeflorus, enquanto em P. pubescens eles cobrem todo o NEF. O tecido secretor consiste de células parenquimáticas com citoplasma denso. O néctar alcança a superfície dos NEFs pela ruptura da fina cutícula que cobre o pólo secretor, uma vez que ambas as espécies não apresentam estômatos ou qualquer outra interrupção da epiderme neste local. A diferença básica entre as duas espécies, em relação aos NEFs, é a densidade da pubescência, que é sempre maior em P. pubescens. Modificações estruturais e de dimensões podem ser observadas até mesmo entre os nectários basais e apicais de uma mesma raque, e portanto tais modificações não apresentam valor taxonômico.Extrafloral nectaries (EFNs) are structurally variable and widely spread among the angiosperms. The occurrence of EFNs in leaves of Pterodon polygalaeflorus Benth. and Pterodon pubescens Benth. (Fabaceae: Papilionoideae) were detected in adult specimens, at the time of production of new buds and flowers. The goals of the present study are to register the occurrence of the EFNs in P. pubescens and P. polygalaeflorus, and provide comparative data on the anatomical structures. The EFNs occur in the rachis and are located under the insertion of each petiolule. Each nectary consists of a small elevation whose apical portion is deeply invaginated, resulting in a depression (secretory pole), a common characteristic of both species. Unicellular, nonglandular trichomes occur along the rachis, being less numerous in P. polygalaeflorus while in P. pubescens they cover the EFNs. The secretory tissue consists of parenchyma cells with dense cytoplasm compactly arranged. The nectar reaches the surface of the EFNs by rupturing the thin cuticle which covers the secretory pole, since both species lack stomata or any other interruption at the epidermis. The basic difference between the two species, in relation to the EFNs, is the density of the pubescence, which is always greater in P. pubescens. Structural and dimensional modifications may be observed, even between basal and apical nectaries in the same rachis, so it does not constitute a taxonomical tool

Galling insects are bioindicators of environmental quality in a Conservation Unit

Galls are well distributed across the World and among plant families. Their diversity can support the status of conservation of an area as an urban park, once inventories are presented. These inventories also help to understand the morphological patterns of the galls, based on their most common shape, color, host botanical families, inducers and galled organs. This study is about an inventory of galls at Parque Estadual Serra Verde, Brazil. This conservation unit is an urban park strongly anthropized in a transition area of Cerrado and Mata Atlântica. Galls from four different trails were observed, and collected monthly during one year. The terminology morphospecies was used to distinguish the galls because the identification of the inducers were not always possible. Seventy five morphospecies of galls belonging to 43 host plant species of 24 botanical families were observed. Mostly of the galls was induced by Diptera:Cecidomyiidae, in Fabaceae and Myrtaceae. The most common traits were the globoid shape and green color. The leaves were the most frequent galled organ and followed by the stems. All these tendencies had been already observed in other inventories. Comparing current results with other studies at similar areas, we can assume that the Parque Estadual Serra Verde is very important for conservation. Urban green areas are subject to high disturbance and degradation but also increase the quality of life for the population inhabiting the areas nearby. The diversity of galls at Parque Estadual Serra Verde reflects an area with high levels of stress but with moderate botanical diversity. These features make this protected area an important site for the continuous conservation and regeneration, and highlight the environmental value of Parque Estadual Serra Verde

Influence of leaflet age in anatomy and possible adaptive values of the midrib gall of Copaifera langsdorffii (Fabaceae: Caesalpinioideae)

Gall inducing insects most frequently oviposit in young tissues because these tissues have higher metabolism and potential for differentiation. However, these insects may also successfully establish in mature tissues as was observed in the super-host Copaifera langsdorffii. Among C. langsdorffii gall morphotypes, one of the most common is a midrib gall induced by an undescribed species of Cecidomyiidae. Following this ‘host plant and gall-inducing insect’ model, we addressed two questions: 1) Do the age of the tissues alter the gall extended phenotype? 2) Do gall morphological and anatomical features influence the adaptive value of the galling insect? For anatomical and histometrical studies, transverse sections of young and mature, galled and ungalled samples were prepared. Galls in young leaflets presented higher potential for cell division and greater nutritive reserves, whereas galls in mature leaflets perhaps provide more protection against natural predators and desiccation. Host organ age at the time of oviposition may influence plant cell fates and consequently the interpretation of the adaptive value of insect galls.Gall inducing insects most frequently oviposit in young tissues because these tissues have higher metabolism and potential for differentiation. However, these insects may also successfully establish in mature tissues as was observed in the super-host Copaifera langsdorffii. Among C. langsdorffii gall morphotypes, one of the most common is a midrib gall induced by an undescribed species of Cecidomyiidae. Following this ‘host plant and gall-inducing insect’ model, we addressed two questions: 1) Do the age of the tissues alter the gall extended phenotype? 2) Do gall morphological and anatomical features influence the adaptive value of the galling insect? For anatomical and histometrical studies, transverse sections of young and mature, galled and ungalled samples were prepared. Galls in young leaflets presented higher potential for cell division and greater nutritive reserves, whereas galls in mature leaflets perhaps provide more protection against natural predators and desiccation. Host organ age at the time of oviposition may influence plant cell fates and consequently the interpretation of the adaptive value of insect galls

Variação da fitotoxidez em duas populações de Psychotria Leiocarpa Cham. et Schlecht. (Rubiaceae)

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