The intramandibular glands of workers and queens of Melipona quadrifasciata Lepeletier (Hymenoptera: Apidae), at different ages and from different functional groups, were studied using light and transmission electron microscopy. The results demonstrated that these glands are composed of two types of secretory structures: 1.A hypertrophied epidermis on the dorsal side of the mandible that is an epithelial gland. 2. Free secretory cells filling the inner spaces of the appendices that constitute a unicellular gland. The epithelial gland is larger in the young (1-2-day-old workers), and the gland becomes involuted during the nurse worker stage. The unicellular glands of the workers posses some secretion during all of the studied phases, but secretory activity is more intensive in the foraging workers. Vesicles of secretion are absent in the unicellular glands of queens. These results demonstrate that these glands show functional adaptations in different castes corresponding to the functions of each caste.

A secreção das glândulas mandibulares de operárias recém-emergidas, aprovisionadoras de cria e forrageiras, rainhas virgens e fisogástricas e machos de Melipona bicolor foi analisada através de cromatografia gasosa-espectrometria de massas. Foi verificado que a secreção é composta por uma mistura de hidrocarbonetos, álcoois, ésteres e ácidos. A secreção é casta-sexo específica e difere, também, de acordo com a tarefa desenvolvida pelas operárias e condição fisiológica reprodutiva das rainhas.The mandibular gland secretions of newly emerged, nurse and forager workers, virgin and physogastric queens and males of Melipona bicolor were analyzed by gas chromatography-mass spectrometry. The secretion is composed of a blend of hydrocarbons, alcohols, esters, and acids. The secretion is caste-sex specific and also differs with the tasks performed by the workers and the physiological reproductive condition of the queens.Keywords: GC-MS, mandibular glands, Melipona bicolor, caste, sex, reproductive variation. IntroductionColonies of eusocial bees include males and females, the latter being represented by two castes: workers and queens. The main function of the males is to mate with the queen and, therefore, supply the genetic complementation for female reproduction. The queen influences the behavior and physiology of the infertile females or workers 1,2 that are responsible for every task of colony maintenance, such as nest defense, provisioning, and brood care. In the colony darkness a precise system of chemical communication exists to maintain the interaction among individuals and the organization of the various activities. This chemical communication is based on the production of substances with intra-specific action known as pheromones 4 by numerous exocrine glands dispersed along the bee body. 5The main function of the pheromones produced by the mandibular gland of Apis mellifera honeybee workers is alarm or defense. In contrast, males use their mandibular gland to produce sexual attractants for the queens. The queen produces the "queen substance", 6 a primer pheromone used to prevent worker ovary development and for sexual attraction of males. 1,6,7 Among the workers, there are variations in the composition of the glandular product related to age and type of task performed. Young workers produce mainly 10-hydroxydecenoic acid while older ones, whose task is foraging, produce predominantly 2-heptanone. [8][9][10] In spite of the differences between the glandular products of queens and workers, the same biosynthetic pathways for the production of pheromones is potentially present in both, since it was demonstrated that egg-laying workers of A. mellifera and A. mellifera capensis also produce 9-oxydecenoic acid, which is one of the components of the queen´s mandibular gland secretion. 11Therefore, the presence of the queen in A. mellifera apparently inhibits in workers 12 the production of pheromones typical of the reproductive female.In meliponine bees, mandibular glands occur in queens, workers, and males.13 Whereas ...

In this paper we focus on the occurrence and morphological aspects of exocrine glands in several bee species. Morphology of head labial, mandibular, Dufour, and abdominal tegumentar glands was investigated under light microscopy, scanning electron microscopy and transmission electron microscopy. Most of such glands present cells with cytoplasm homogeneous and acidophilic, or contain small apparently empty vacuoles. The cytoplasm cells' ultrastructure showed a well developed smooth endoplasmic reticulum, many polymorphic mitochondria, rare Golgi, lipid droplets, myelin figures, and many basal and apical plasma membrane infoldings. All these results are discussed in the text.

-The mandibular glands of newly-emerged, nurse and forager workers, virgin and physogastric queens, and mature males of Scaptotrigona postica Latreille were studied under histological and morphometrical analyses. These glands present differences in their histology, according to the age and/or function of the individuals. The morphometric results showed that the mandibular glands have a very markedly secretory cicle, in which the secretion starts to be produced in newly emerged workers, being accumulated into the cytoplasm and reservoir in the nurses. In forager workers the cytoplasm presents many vacuoles, which are remaining of the secretion releasing. Physogastric queens showed the largest cellular and nuclear areas. On the contrary, the males presented the smallest ones.KEY WORDS: Mandibular gland, anatomy, histology, caste, sex, functional state RESUMO -As glândulas mandibulares de operárias recém-emergidas, nutridoras e campeiras, rainhas virgens e fisogástricas, e machos maduros de Scaptotrigona postica Latreille foram estudadas histológica e morfometricamente. Estas glândulas apresentam diferenças histológicas características para cada idade e/ou função do indivíduo. De acordo com a morfometria conclui-se que as glândulas mandibulares possuem um ciclo secretor determinado, no qual a secreção começa a ser produzida nas operárias recém-emergidas, e acumula-se no citoplasma e reservatório da glândula das operárias nutridoras. Nas operárias campeiras o citoplasma encontra-se bastante vacuolizado, o que foi interpretado como resultado da eliminação da secreção. Rainhas fisogástricas apresentaram as maiores áreas celulares e nucleares, ao oposto dos machos, os quais apresentaram as menores áreas. PALAVRAS-CHAVE: Anatomia, histologia, casta, sexo, estado funcional Numa colônia de abelhas eussociais, há uma divisão do trabalho reprodutivo entre as castas femininas, sendo a rainha responsável pela postura e ficando para as operárias todas as outras tarefas da colônia, entre elas a de nutrir a cria. A divisão de trabalho em abelhas está baseada na capacitação do indivíduo para exercer determinada tarefa. No caso das operárias, a capacitação é alcançada através da maturação fisiológica para seu desempenho, adquirida por etapas, com o avanço da idade, o polietismo etário, no qual as estruturas glandulares endócrinas e exócrinas desempenham importante papel.A idade das operárias em que essas glândulas se desenvolvem ou degeneram não está rigidamente estabelecida no programa inato do indivíduo e, aparentemente, nem sequer a seqüência a seguir. Assim as operárias podem responder às necessidades da colônia em um dado momento, ou seja, são as variações das condições do seu meio com ajustes que levam a colônia a funcionar como um superorganismo. Assim, o redirecionamento fisiológico dos tecidos e órgãos acontece (Cruz-Landim & Silva de Moraes 2000)As glândulas de especial interesse neste trabalho são as glândulas mandibulares, as quais são compostas por células da classe III, segundo Noirot & Quennedey (1974, 1991...

-Class III tegumentar glands were studied in workers, as well as in queens and males when available, of 56 Meliponini species. The presence and development of these glands varies widely among and within species. However, the queen typically has more glands than do workers, and males rarely have any. Gland development in workers was evaluated by counting and determining the size of cells in histological sections. Laying queens were found to have more active gland cells than did virgins. Cell numbers and cell ultrastructure differed among glands similarly located in workers, queens and males. Cell size and ultrastructure also varied from tergite to tergite. In conclusion, since it is likely that most of them produce pheromones, the wide variability in these glands suggests that they are important to social interaction. stingless bee / tergal gland / histology / ultrastructure / worker / queen / male