Ontogenia da casta de soldados no cupim praga Heterotermoes tenuis (Isoptera, Rhinotermitidae)

Heterotermes tenuis é uma espécie de cupim nativa da região Neotropical, conhecida como praga agrícola e urbana. Essa espécie causa sérios danos econômicos em culturas de cana-de-açúcar e ataca madeiras e derivados celulósicos em cidades. H. tenuis apresenta hábitos subterrâneos e indivíduos de pequeno porte, com soldados dimórficos. A diferenciação de castas nos cupins é um processo complexo ainda não totalmente esclarecido. Em vista disso, o objetivo do presente estudo foi entender a diferenciação de soldados no cupim H. tenuis a partir de agrupamentos de operários. Para isso, no Capítulo I, foram apresentados os resultados dos bioensaios desenvolvidos para observar a influência de fatores extrínsecos e intrínsecos, entre eles, número de operários agrupados, temperatura, fontes alimentares e ingestão de diferentes concentrações de piriproxifen, um análogo de hormônio juvenil. Agrupamentos com 50, 100, 200 e 300 operários formaram uma baixa proporção de soldados. O uso de piriproxifen originou pré-soldados e também intercastas, sendo que a formação de pré-soldados foi maior na concentração de 10 ppm. Já no Capítulo II, o foco do estudo foram as mudanças morfológicas externas e internas ocorridas durante o processo de diferenciação de soldados. Para isso, operários, pré-soldados, soldados e intercastas foram submetidos à análise biométrica e histológica. Além disso, foi realizada a identificação do sexo dos soldados e a determinação da duração do ínstar de pré-soldado. Este ínstar durou cerca de 15 dias em temperatura ambiente e os pré-soldados diferiram biometricamente dos soldados, principalmente, pelo comprimento da cápsula cefálica e do tórax. As intercastas obtidas foram do tipo operário-soldado. Soldados menores de H. tenuis foram todos machos enquanto os soldados maiores apresentaram uma proporção de aproximadamente...Heterotermes tenuis is a native species of termite, known as an agricultural and urban pest. This species causes serious economic damages on crops of sugar cane and attacks wood and cellulosic derivatives in cities. H. tenuis has subterranean habits and small individuals, with dimorphic soldiers. Differentiation of castes in termites is a complex process not yet fully understood. In this study we aimed to understand the differentiation of H. tenuis soldiers, originated from groups of workers. In Chapter I, we presented the results of bioassays developed to observe the influence of extrinsic and intrinsic factors, including, number of grouped workers, temperature, food sources and ingestion by the workers of different concentrations of pyriproxyfen, a juvenile hormone analog. Groups of 50, 100, 200 and 300 workers originated a low proportion of soldiers. The use of pyriproxyfen induced presoldiers and also intercastes. Presoldiers were produced in a large number in a concentration of 10 ppm. In Chapter II, the focus of the study was the external and internal morphological changes occurred during the process of differentiation of soldiers. For that, workers, presoldiers, soldiers and intercastas were histologically and morphometrically analyzed. In addition, we performed the sex identification of the soldiers and determined the duration of the presoldier instar. This instar lasted about 15 days at a variable temperature and the presoldiers biometrically differed from soldiers mainly by the length of head capsule and thorax. The intercastes obtained were from the worker-soldier type. Minor soldiers of H. tenuis were all males while the major soldiers had a ratio of approximately 1:1 between males and females. The exocrine glands of the individuals studied were compared and the histology showed that workers had greater development of the salivary, mandibular and sternal glands... (Complete abstract click electronic access below)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Morfologia e desenvolvimento do sistema reprodutor em três espécies de Isoptera

Kings of Isoptera supply large quantities of viable sperm to the queens. Nevertheless, the study of the male reproductive system of these insects has been neglected when compared to that of females. In order to fill this gap, this research aimed a comparative study of the reproductive system in different ages of termite males, including nymphs and winged reproductives. Thus, three species were chosen from three families that have different evolutionary positions: Cryptotermes brevis, Coptotermes gestroi and Silvestritermes euamignathus. Chapter I emphasized the production of sperm and development of seminal vesicles in last instar nymphs, alates and 6-month and 1-year-old kings of C. brevis. In nymphs, the sperm are restricted to the testicles. Chapter II focuses primarily on the histochemistry and ultrastructure of the seminal vesicles of C. gestroi and records the beginning of spermatogenesis in 3rd instar nymphs, even though 5th instar nymphs have not stored sperm in the seminal vesicles. In this species, individualized seminal vesicles have a secretory distal region and a proximal region with sperm storage function. In addition, the histochemistry showed polysaccharides and proteins present in the secretion of these structures at the distal region. In Chapter III, the evolution of the reproductive system in male of S. euamignathus was followed. The results showed an early maturation of the reproductive system of males and the increasing sperm production in kings of mature colonies. Additionally, morphological and histochemical data allowed us to infer that the seminal vesicles of kings function more likely as a sperm storage organ than secretory structures. Chapter IV is dedicated to an analysis of the gonads of replacement reproductives, which were collected in three different colonies of C. brevis. Colonies A and B were formed by a couple containing a neotenic and a primary reproductive. The primary king and the neotenic king showed ...Reis de Isoptera fornecem grandes quantidades de espermatozoides viáveis à rainha. Contudo, o estudo do sistema reprodutor dos machos destes insetos tem sido negligenciado quando comparado ao das fêmeas. Com o objetivo de suprir essa lacuna, a presente pesquisa visou um estudo comparativo do sistema reprodutor em diferentes idades desses machos, incluindo ninfas e reprodutores alados. Desse modo, foram escolhidas três espécies, pertencentes a três famílias que ocupam posições evolutivas diferentes: Cryptotermes brevis, Coptotermes gestroi e Silvestritermes euamignathus. No Capítulo I, foi dado destaque à produção de espermatozoides e desenvolvimento das vesículas seminais em ninfas de último ínstar, reprodutores alados e reis com 6 meses e 1 ano de idade de C. brevis. Nas ninfas, os espermatozoides estão restritos aos testículos. O Capítulo II enfoca principalmente a histoquímica e ultraestrutura das vesículas seminais de C. gestroi e assinala o início da espermatogênese em ninfas de 3º ínstar, apesar de ninfas de 5º ínstar ainda não estocarem espermatozoides nas vesículas seminais. Nesta espécie, as vesículas seminais individualizadas apresentam uma região distal secretora e uma região proximal com função de armazenamento de espermatozoides. Adicionalmente, a histoquímica evidenciou polissacarídeos e proteínas na secreção presente na região distal destas estruturas. No Capítulo III, foi acompanhada a evolução do aparelho reprodutor em machos de S. euamignathus. Os resultados mostraram um amadurecimento precoce do sistema reprodutor dos machos e um aumento da produção de espermatozoides em reis de colônias maduras. Além disso, as vesículas seminais aumentaram muito nestes indivíduos e se apresentaram como porções especializadas dos dutos deferentes. Adicionalmente, dados morfológicos e histoquímicos permitem inferir que as vesículas seminais de reis funcionam mais como órgão de...Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Disappearance of fat body proteins during soldier differentiation in the neotropical termite Heterotermes tenuis (Isoptera: Rhinotermitidae)

Termites are social insects with well-defined castes: workers, soldiers and reproductives. The soldier is a terminal stage and originates from either larvae or workers after two molting processes that include an intermediate presoldier instar. The present study followed the occurrence and morphological changes of the fat body during the soldier ontogeny in the neotropical termite Heterotermes tenuis. Workers and soldiers collected in the field and presoldiers obtained in laboratory were fixed in FAA fixative and embedded in resin for light microscopy. The histological sections were submitted to histochemical tests for protein and urate detection. The fat body in all the individuals showed only two cellular types: adipocytes and urocytes. The adipocytes of presoldiers displayed some lipid droplets, and a large amount of acidophilic granules interpreted as proteins because they were strongly stained by xylidine Ponceau. In soldiers, the fat body was deprived from proteins and showed a higher quantity of urocytes with many urate spherocrystals compared with those present in workers and presoldiers. The results were consistent with metamorphosis process and with the possibility of presoldiers being at the beginning of molting stage. The occurrence of many protein granules suggests uptake and consumption of protein storage during the whole development of the presoldiers into soldiers. The dynamic transformations of the fat body enable the individuals of different phenotypes to accomplish their role in the termite colony.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Tergal glands in termite soldiers of the subfamily Syntermitinae (Isoptera: Termitidae)

The subfamily Syntermitinae comprises 14 genera of termites that are exclusively neotropical. The present study reports morphological data about mandibulate nasute soldiers from termite species belonging to three different genera within this subfamily. We describe tergal glands that were present under all tergites of soldiers of the following species: Cornitermes cumulans, Procornitermes araujoi, Syntermes nanus, and Syntermes wheeleri. The tergal glands were composed of class 2 and class 3 cells. Class 2 cells never reached the cuticle and were located below a flat layer of epidermal cells. Class 3 cells, composed of secretory cells and canal cells, were sporadic, whereas class 2 secretory cells were abundant. Secretory cells of class 3 were narrow and their cytoplasms were filled with several clear, oval-shaped vesicles with limiting membranes. The ultrastructure of class 2 cells showed well-developed smooth endoplasmic reticulum, Golgi apparatus, elongated mitochondria, several electron-lucent vesicles, and electron-dense granules that contain paracrystalline structures in S. nanus. Scanning electron micrographs displayed pores, campaniform sensilla and hairs in the outer cuticle of the soldier tergites. We hypothesize that soldier tergal glands may be involved in the production of defensive compounds, which occur in similar glands of certain cockroaches, or of primer pheromones, that might act in the regulation of soldier differentiation in the termite colony. To date, tergal glands have only been described in termite imagoes, and their occurrence in these soldiers of basal Syntermitinae implies a specific role in this caste that is still speculative and needs to be clarified. (C) 2011 Elsevier Ltd. All rights reserved.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

The fat body of termites: Functions and stored materials

The functions of the fat body in the different castes of termites, and accumulation of energy reserves, proteins and urates within this organ, are reviewed. The termite fat body is involved in multiple metabolic activities, including recycling of nitrogen. Termite fat body showed three different types of cells: adipocytes, urocytes and mycetocytes, the latter restricted to the species Mastotermes darwiniensis. Adipocytes synthesize and store lipids, glycogen and several proteins. These cells also elaborate important peptides, including some that act in immune processes. Urocytes are responsible for the storage of spherocrystals of urates, which vary quantitatively among the termite castes. The different metabolic functions of the fat body in the several castes and stages of termites are associated with specific adipocyte morphologies. The synthesis and storage of different compounds modify the structure of the fat body; this differentiation is coordinated by hormones involved with molting and reproductive cycles. © 2013 Elsevier Ltd

Location, morphology and function of nephrocytes in termites

Insect nephrocytes are cells bathed in hemolymph and considered to have an excretory function. These cells have ambiguous nomenclature and are understudied in termites. This study is the first report on the occurrence, morphology and function of nephrocytes in different termite castes. Cytological characteristics in specific developmental stages and castes enable physiological functions to be inferred. Perforate diaphragms indicate a role in filtration, while the extensive peripheral invaginations of the cell membrane suggest active endocytosis. A sequence of morphologies in putative digestive vacuoles infers a lysosomal system and the occurrence of phosphatases suggests a function involving detoxification of substances sequestered from hemolymph. Pericardical nephrocytes took up the dye trypan blue injected in live termites, suggesting their activity connected to the filtration of the hemolymph. Additionally, histochemical tests showed the existence of stored proteins in their cytoplasm. These cells present a well-developed Golgi apparatus and abundant rough endoplasmic reticulum, consistent with protein synthesis. This study highlights the importance of nephrocytes in Isoptera and opens perspectives for further research of these cells.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Tarsomere and distal tibial glands: structure and potential roles in termites (Isoptera: Rhinotermitidae, Termitidae)

Social insects have numerous exocrine glands, but these organs are understudied in termites compared to hymenopterans. The tarsomere and distal tibial glands of the termites Heterotermes tenuis, Coptotermes gestroi and Silvestritermes euamignathus were investigated by scanning and transmission electron microscopy. Pore plates are visible in scanning micrographs on the distal tibial surfaces and on the ventral surface of the first and second tarsomeres of workers of H. tenuis and C. gestroi. In contrast, workers of S. euamignathus have isolated pores spread throughout the ventral surfaces of the first, second, and third tarsomeres and the distal tibia. In all three species each pore corresponds to the opening of a class-3 secretory unit, composed of one secretory and one canal cell. Clusters of class-3 glandular cells are arranged side by side underneath the cuticle. The main characteristics of these exocrine glands include their presence on all the legs and the electron-lucent secretion in the secretory cells. Possible functions of these glands are discussed.Conselho Nacional de Desenvolvimento Científico e Tecnologico (CNPq