COMPARATIVE STUDIES ON PIGMENT GRANULES AND PIGMENT DISTRIBUTION IN THE COMPOUND EYES OF WILD-TYPE AND MUTANT WORKER HONEYBEES .2. AN ULTRASTRUCTURAL ANALYSIS

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Simple heuristics for the assembly line worker assignment and balancing problem

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Storaged products and presence of acid phosphatase in fat body cells at pre-pupal worker stage of Apis mellifera Linnaeus, 1758 (Hymenoptera, Apidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Morphological prediction of worker size discrimination and relative abundance of sympartic species of Pseudacteon (Dipt., Phoridae) parasitoids of the fire ant, Solenopsis saevissima (Hym., Formicidae) in Brazil

Patterns of attack for collected species of phorids are predicted using multivariate morphometrics of female Pseudacteon species and worker size distributions of parasitized fire ants, Solenopsis saevissima. The model assumes that there is a direct correlation between phorid size and the size range of the worker ant attacked, and presumes that worker sizes are a resource that is divided by sympatric phorid species to minimize joint parasitism. These results suggest that the community of sympatric Pseudacteon species on only one host species coexists by restricting the size of workers attacked, and secondarily by differing diel patterns of ovipositional activity. When we compared relative abundance of species of Pseudacteon with the size distribution of foragers of S. saevissima, our observed distribution did not differ significantly from our predicted relative abundance of females of Pseudacteon. The activity of Pseudacteon may be a factor determining forager size distributions.

Honey Ants (Genus Myrmecocystus) Macroecology: Effect of Spatial Patterns on the Relationship between Worker Body Size and Geographic Range Size

Macroecology evaluates the partitioning of physical space and resources among organisms through correlation among ecological variables, such as geographical range size and shape, body size, and population density, measured at large geographical and taxonomic scales. In this article, we analyzed the spatial patterns in worker body size and geographic range size for the 27 described species of honey ants, genus Myrmecocystus Wesmael, in the United States and Mexico, and especially the relationship between these 2 variables after statistically removing their spatial patterns. The 2 variables are correlated, but also displayed significant spatial patterns, as detected by trend surface and spatial autocorrelation analyses. After removing these spatial effects, worker body size and geographic range size were still positively correlated. The relationship, therefore, is not a consequence of spatial effects and it does follow Brown's model, which predicts that the geographic range size will have a positive slope on body size. In this model, the lower population densities caused by foraging activities and local territorial competition are associated with a large geographic range, avoiding stochastic extinction. Although this constraint in local population density does not necessarily hold for small organisms such as insects that could achieve high densities even in very small areas and patchy habitats, it may hold for social insects, especially ants, because of the local competition among colonies.

Cell death in ovarioles causes permanent sterility in Frieseomelitta varia worker bees

Frieseomelitta varia worker bees do not lay eggs even when living in queenless colonies, a condition that favors ovary development and oviposition in the majority of highly social bees. The permanent sterility of these worker bees was initially attributed to a failure in ovary morphogenesis and differentiation. Using transmission electron microscopy we found that at the beginning of the pupal phase the ovaries of F. varia workers are formed by four ovarioles, each of them composed of 1) a terminal filament at the apex of the ovarioles, containing juxtaposed and irregularly shaped cells, 2) a germarium with clusters of cystocytes and prefollicular cells showing long cytoplasmic projections that envelop the cystocyte clusters, 3) fusiform interfollicular and basal stalk precursor cells, and 4) globular, irregularly contoured basal cells with large nuclei. However, during the pupal phase an accentuated and progressive process of cell death takes place in the ovarioles. The dying cells are characterized by large membrane bodies, electron-dense apoptotic bodies, vacuoles, vesiculation, secondary lysosomes, enlarged rough endoplasmic reticulum cisternae, swollen mitochondria, pycnotic nuclei, masses of chromatin adjacent to the convoluted nuclear envelope, and nucleoli showing signs of fragmentation. Cell death continues in ovarioles even after the emergence of the workers. Once they become nurse bees, the ovaries have become transformed into a cell mass in which structurally organized ovarioles can no longer be identified. In F. varia workers, ovariole cell death most certainly is part of the program of caste differentiation.

Differential morphology of the hemocytes present in pupal ovaries of the queen and worker honeybee

The location and morphological features of the blood cells found in the pupal ovary of workers and queens of Apis mellifera are described in relationship with their probable function in the ovary differentiation. The hemocytes from inside the ovarioles are different in both castes. In queens their morphology suggest an action in the tunica propria production, while in workers it suggest a phagocytic activity. The hemocytes present in the intersticial tissue are phagocytes in both castes, and may be responsible by the ovary shapping during metamorphosis.

Histological and morphometric comparisons of worker and queen mandibular glands of Melipona bicolor bicolor (Hymenoptera, Meliponini)

In the present investigation we analyzed both histology and area of secretory cells from workers, virgin and physogastric queen mandibular glands of Melipona bicolor bicolor Lepeletier. The histological differences observed include the number of vacuoles present in the cell cytoplasm and the quantity and distribution of the secretion. The morphometry results demonstrated the occurrence of significative differences in the cell area values that were related to the secretory cell activity level, which is higher in the physogastric queens. Worker and queen glands have histological patterns quite similar, but the morphometric data indicated cast-specific differences, as well as differences between the queens, which were related to the posture activity.

Juvenile hormone promotes changes in the expression of hypopharyngeal gland proteins of worker Apis mellifera (Hymenoptera: Apidae)

The present investigation compares the protein electrophoreses profiles of the hypopharyngeal glands of 12 and 25 day old Apis mellifera workers, some of which were experimentally treated with an analogue of juvenile hormone in the moment of the emergence while others were not treated. According to the evaluation of the presented variations by four main bands, it is concluded that the analogue juvenile hormone changes the glandular genetic expression pattern, promoting the disappearance of two from the four main bands in 25 day old workers. The effect of this hormone is discussed as an hypopharyngeal maturation inductor, in synergetic action with the bee age acting early in the glandular cycle.

Ovarian growth during larval development of queen and worker of Apis mellifera (Hymenoptera: Apidae): a morphometric and histological study.

The present work reports the differences between the ovarian grow in queen and worker larvae of A. mellifera, from the start of differential feeding. The observations made of the growth rates in larvae of both castes showed that the queen and worker larvae have the same rates of cephalic capsule growth from one instar to another but the weight gain is greater in queens. In the same way, the draw areas of ovaries of queens increase more and continuously, while from the 5th instar on the ovaries of workers decrease in size. The decrease is due to a loss of ovariole numbers that starts early in the worker larvae and increases in the 4th-5th instar. The ovarian shape in queens and workers became different in the last larval instars.

Influence of the application of juvenile hormone on the haemolymph total proteins and electrophoretic pattern of worker larvae of Apis mellifera

The aim of the present work was to verify the influence of the juvenile hormone (JH) applied on worker larvae of Apis mellifera 2 to 5 days old over the haemolymph total protein and electrophoretic pattern. Each larvae received topical applications of 1 ml of a solution of JH in hexane (1 μg/ml) on their 2 nd, 3 rd 4 th and 5 th day after hatching and had the amount and electrophoretic pattern of proteins from the haemolymph analyzed during the remaining days of their life. As a control, haemolymph of larvae of the same age that did not receive any kind of treatment was analyzed. The results show that the application of JH on larvae 3 or more days old affect the amount and electrophoretic pattern of the proteins, with this effect lasting through the subsequent days.

Development of worker ovaries in Brazilian Africanized honeybees (Hymenoptera: Apidae)

The present paper compares the worker ovaries development in queen right and orphaned colonies of Brazilian Africanized honeybee. The results show that in both colonies some workers starting 20 days after emergence, present some kind of ovary development. As the workers from queen right colony get older the degree of the ovary development increases. Vitellogenesis in worker ovaries may occur in queen right and orphaned colonies, but its frequency is lower in queen right colonies.

Morphohistochemical characterization of the perivisceral fat body in royal and worker female castes in different ages of Atta sexdens rubropilosa ants (Hymenoptera, Formicidae)

The morphohistochemical study of the fat body in royal and worker castes of Atta sexdens rubropilosa revealed that this tissue is made up of trophocytes and oenocytes, trophocytes being the cells with cytoplasmic inclusions and irregular nuclei and the oenocytes cells with homogeneous cytoplasm and rounded nuclei. The trophocytes of queens presented many lipidic and proteic granules, while those of workers presented trophocytes with fine granulation in the cytoplasm constituted mainly by lipids and carbohydrates. The oenocytes from the worker caste of A. s. rubropilosa presented cytoplasm filled mainly with lipoproteic material.

The role of workers in transferring queen substances and the differences between worker castes in the leaf-cutting ant, Acromyrmex subterraneus brunneus (Hymenoptera: Formicidae)

The present study focused on the relationship between the queen and workers in Acromyrmex subterraneus brunneus colonies mediated by the possible transfer of substances from the fertile to the sterile caste. The queens were submitted to different situations of physical limitation, i.e., they were kept isolated in cages with holes that only permitted the entry of workers but left the queen isolated. A tracer (water-soluble dye) was applied to the pronotum and gaster of the queen and its dispersal among workers was analyzed. The results demonstrated that the minor sub caste (0.7-0.9 mm) passed on the dye through allogrooming and self-grooming, or transferred the dye through trophallaxis to the major sub caste (1.2-2.0 mm) when they were not in direct contact with the queen. These findings indicate the communication and probable transfer of substances from the queen to the workers, as well as a substance transfer between workers.