Development of antennal sensilla of Tetragonisca angustula Latreille, 1811 (Hymenoptera: Meliponini) during pupation / Desenvolvimento das sensilas antenais de Tetragonisca angustula latreille, 1811 (Hymenoptera: Meliponini) durante a pupação

Abstract The antennal sensilla are sensory organs formed by a group of neurons and accessory cells, which allow perception of environmental cues, which play a role as mechanoreceptors and chemoreceptors. This study describes the post-embryonic development of the antennal sensilla of the stingless Tetragonisca angustula (Hymenoptera: Meliponini) workers. The development of the antennal sensilla begins in the transition stage of the pre-pupae to white-eyed pupae. The sensilla are completely developed at the black-eyed pupae stage, but they are covered by the old cuticle. The sensilla are exposed to the environment only in newly emerged workers of T. angustula, but it is possible that environmental stimuli can be recognized due to the pores in the old cuticle.

Resumo As sensilas antenais são órgãos sensoriais formados por um conjunto de neurônios que captam estímulos ambientais e células acessórias, desempenhando as funções de mecanorreceptores e quimiorrecepterores. Este trabalho descreve o desenvolvimento pós-embrionário das sensilas antenais de operárias das abelhas sem ferrão Tetragonisca angustula (Hymenoptera: Meliponini). O desenvolvimento das sensilas tem início na transição de pré-pupa para pupa de olho branco e estão completamente desenvolvidas no estágio de pupa de olho preto, mas ainda estão cobertas pela cutícula velha. As sensilas estão completamente expostas em operárias recém-emergidas de T. angustula, mas é possível que estímulos ambientais sejam percebidos em estágios anteriores devido aos poros presentes na cutícula velha.

Ultrastructural modifications in the venom glands of workers of Apis mellifera L. (Hymenoptera: Apidae) promoted by topical application of juvenile hormone

The present study analyzed, the influence of the treatment with juvenile hormone on the ultrastructure of Apis mellifera L. workers' venom glands. Newly emerged workers received topical application of 1 æl of juvenile hormone diluted in hexane, in the concentration of 2 æg/æl. Two controls were used; one control received no treatment (group C1) and other received topical application of 1 æl of hexane (group C2). The aspect of the glandular cells, in not treated newly emerged workers, showed that they are not yet secreting actively. Cellular modifications happened according to the worker age and to the glandular area considered. The most active phase of the gland happened from the emergence to the 14th day. At the 25th day the cells had already lost their secretory characteristic, being the distal area the first to suffer degeneration. The treatment with juvenile hormone and hexane altered the temporal sequence of the glandular cycle, forwarding the secretory cycle and degeneration of the venom gland.

O presente estudo analisou, através de estudos ultra-estruturais a influência do tratamento com hormônio juvenil sobre as glândulas de veneno de operárias de Apis mellifera L. Para tanto, operárias recém-emergidas receberam aplicação tópica de 1æl de hormônio juvenil, na concentração de 2 æg/æl, sendo usado o hexano como veículo. Foram feitos dois controles, um que não recebeu nenhum tipo de tratamento (grupo C1) e o outro que recebeu aplicação tópica de 1 æl de hexano (grupo C2). O aspecto das células glandulares, em operárias recém-emergidas, mostra que estas não estão ainda secretando ativamente. Observa-se que alterações celulares ocorrem de acordo com a idade da operária e da região glandular considerada no controle C1. Assim, a fase de secreção mais ativa da glândula ocorre entre a emergência e os 14 dias de idade; aos 25 dias as células já perderam sua característica secretora, sendo a região distal a primeira a sofrer degeneração. Os tratamentos com hormônio juvenil e com hexano alteram a cronologia do ciclo glandular, antecipando o início da secreção e da degeneração da glândula.

Cell death and ovarian development in highly eusocial bees (Hymenoptera, apidae): caste differentiation and worker egg laying

The development and functioning of the ovary in highly eusocial bees is one of the most prominent differences between the castes in these insects, with queens having very large ovaries and a high capacity to produce eggs while the workers have small, sub-functional ovaries. The differences in ovary size and function are established during larval and pupal development and are hormonally controlled. Differential cell death has a prominent role in modulating the ovarian differences during development and adulthood. In this review, we discuss the forms of cell death, the types of cells affected and the timing of death in relation to the function of the female castes in the colony.

Cell death in the Germline: mechanisms and consequences for reproductive plasticity in social bees

Its serial architecture makes the insect ovary an interesting playground to study the regulation of cell death and identify critical check points along the apical-basal axis of the ovarioles. In Drosophila melanogaster, cell death is observed at two points: (1) in the germarium, where entire germ cell clusters may die in response to environmental conditions, and (2) as an obligatory event at the end of oogenesis, when nurse cells dump their cytoplasm into the oocyte and, subsequently, when the follicle epithelial cells form a chorion. The social organization of bees, wasps and ants depends on the monopolization of reproduction by a queen. This has marked consequences on the ovary phenotype of queens and workers. The role of programmed cell death in larval ovary development and in adult ovary function is best studied in honey bees. During larval development, workers loose over 90% of the ovariole primordia. This cell death is induced by a low juvenile hormone titer causing breakdown of the actin cytoskeleton in germ cell clusters. The actin cytoskeleton also plays a major role in the control of cell death in the ovary of adult bees, where many TUNEL-labeled and pycnotic nuclei are detected in a germarial region rich in actin agglomerates. This suggests that common mechanisms may regulate cell death in the ovaries of bees, both during the shaping of the caste-specific ovary phenotypes during larval development, and during the tuning of reproductive activity in adult bees.

Ultrastructural aspects of the intercellular bridges between female bee germ cells

No ovário das abelhas as células germinativas e as células foliculares são interconectadas por pontes intercelulares mantidas abertas por reforços do citoesqueleto na membrana plasmática. As pontes entre as células germinativas têm comportamento dinâmico e provavelmente atuam na determinação do ovócito entre as células do clone formado pelas mitoses pré meióticas formando posteriormente uma via de transporte para que os produtos sintetizados pelas células nutridoras atinjam o ovócito durante sua maturação. Os elementos do citoesqueleto presentes nas pontes intercelulares das gônadas das abelhas são basicamente microfilamentos e microtúbulos, mas nas pontes entre os cistócitos pré-meióticos outro tipo de filamento (espesso de natureza não definida, associado a elementos do retículo endoplasmático) está presente, atravessando a ponte e prendendo-se através dos microfilamentos à membrana plasmática. Estes filamentos aparentemente controlam o vão da ponte. Terminada a fase de proliferação os cistócitos tomam a forma de uma roseta e um fusoma, formado pela convergência das pontes, aparece no centro desta. Nesta conformação os filamentos grossos não estão presentes. Nova mudança ocorre com a diferenciação do ovócito e das células nutridoras, com a reorientação de todas as pontes de maneira a canalizar o conteúdo das futuras células nutridoras para o ovócito.

Morphology and protein patterns of honey bee drone accessory glands

We used light and transmission electron microscopy to examine the morphology of the accessory glands of immature and mature adult males of Apis mellifera L. We also made an electrophoretic analysis of the protein content of the mature gland. The glands of the immature male actively secrete a mucous substance that can be seen in the lumen of the gland of the mature male. This secretion stains with mercury bromophenol blue and with periodic acid-Schiff reaction, which stain glyconjugates. The protein content was higher in the lumen secretion than in the gland wall extracts. The electrophoresis patterns of the wall extracts were different from those of the secretion found in the gland lumen.

Feulgen staining in malpighian tubules of meliponid bees: a methodological contribution

Whole-mounted Malpighian tubules of larvae from two meliponid bee species fixed in acetic acid-ethanol showed apositive cytoplasmic staining with Schiff reagent when submitted to the Feulgen reaction in which acid hydrolysiswas done in 4 M HCl at room temperature. The ability of various treatments applied before the Feulgen acid hydrolysisto abolish this cytoplasmic staining was examined. The aldehyde groups of phospholipids present in the cytoplasm ofthe Malpighian tubules were blocked or removed by sequential treatment with 5% sodium borohydride and acetonechloroform(1:1, v/v) for 15 min each prior to HCl hydrolysis. This treatment is recommended in order to abolish thecytoplasmic (plasmal) reaction and to allow the reliable quantification of DNA by the Feulgen reaction and thediscrimination of nuclear phenotypes in the Malpighian tubules of meliponid bees.

Cell nucleus activity during post-embryonic development of Apis mellifera L. (Hymenoptera: Apidae). Intranuclear acid phosphatase

We report nuclear acid phosphatase activity in the somatic (intra-ovariolar and stromatic) and germ cells of differentiating honey bee worker ovaries, as well as in the midgut cells of metamorphosing bees. There was heterogeneity in the intensity and distribution of electron dense deposits of lead phosphate, indicative of acid phosphatase activity in the nuclei of these tissues, during different phases of post-embryonic bee development. This heterogeneity was interpreted as a variation of the nuclear functional state, related to the cell functions in these tissues

Replacement of larval by adult Malpighian tubules during metamorphosis of Melipona quadrifasciata anthidioides Lep. (Hymenoptera, Apidae, Meliponinae): morphological studies

In Melipona quadrifasciata anthidioides a stingless bee, the malpighian tubules (Mt) of the larvae are totally reabsorbed during pupation and replaced by others that will function in the adult. The dye exclusion test shows generalized celular death in the larvall tubules present in prepupae. The results obtained with the acid phosphatase reaction corroborate these findings. Between the end of larval phase and emergence of adult, the insect does not have functional malpighian tubules, but develops waste storaging cells, the urate cells, for nitrogenous waste inactivation. the morphology of degeneration of the larval and the arising of the adult Mt, as well as that of the urate cell on light microscopy are described. The apparent change in the connection point between intestine and malpighian tubules of larva and adult is also discussed.