Discrete dimorphism among castes of the bald-faced hornet Dolichovespula maculata (Hymenoptera: Vespidae) in different phases of the colony cycle

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

Castes and asynchronous colony cycle in Polybia bistriata (Fabricius) (Hymenoptera: Vespidae)

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

Resistance to experimental autoimmune encephalomyelitis development in Lewis rats from a conventional animal facility

Experimental autoimmune encephalomyelitis (EAE) is an inflammatory disease of the brain and spinal cord that is mediated by CD4+ T lymphocytes specific to myelin components. In this study we compared development of EAE in Lewis rats from two colonies, one kept in pathogen-free conditions (CEMIB colony) and the other (Botucatu colony) kept in a conventional animal facility. Female Lewis rats were immunized with 100 µl of an emulsion containing 50 µg of myelin, associated with incomplete Freund's adjuvant plus Mycobacterium butyricum. Animals were daily evaluated for clinical score and weight. CEMIB colony presented high EAE incidence with clinical scores that varied from three to four along with significant weight losses. A variable disease incidence was observed in the Botucatu colony with clinical scores not higher than one and no weight loss. Immunological and histopathological characteristics were also compared after 20 days of immunization. Significant amounts of IFN-gamma, TNF-alpha and IL-10 were induced by myelin in cultures from CEMIB animals but not from the Botucatu colony. Significantly higher levels of anti-myelin IgG1 were detected in the CEMIB colony. Clear histopathological differences were also found. Cervical spinal cord sections from CEMIB animals showed typical perivascular inflammatory foci whereas samples from the Botucatu colony showed a scanty inflammatory infiltration. Helminths were found in animals from Botucatu colony but not, as expected, in the CEMIB pathogen-free animals. As the animals maintained in a conventional animal facility developed a very discrete clinical, and histopathological EAE in comparison to the rats kept in pathogen-free conditions, we believe that environmental factors such as intestinal parasites could underlie this resistance to EAE development, supporting the applicability of the hygiene hypothesis to EAE.

LARVAL INSTARS AND IMMATURE DEVELOPMENT OF A BRAZILIAN POPULATION OF PHARAOHS ANT, MONOMORIUM-PHARAONIS (L) (HYM, FORMICIDAE)

The immature development of pharaoh's ant, Monomorium pharaonis, workers was s died in a naturally collected Brazilian population. Three larval instars were confirmed by measuring maximal cephalic widths in cohorts of known age. Minimum egg to adult duration was 25 days, while the maximum duration was 54 days, both of which are larger than those reported for European populations. Larval instar development is cyclical at the colony level, suggesting reproductive bursts followed by lower reproductive activity of the queens.

A modified ant colony optimization algorithm modeled on tabu-search methods

An earlier model underlying the foraging strategy of a pachycodyla apicalis ant is modified. The proposed algorithm incorporates key features of the tabu-search method in the development of a relatively simple but robust global ant colony optimization algorithm. Numerical results are reported to validate and demonstrate the feasibility and effectiveness of the proposed algorithm in solving electromagnetic (EM) design problems.

Dominance hierarchy in different stages of development in colonies of the primitively eusocial wasp Mischocyttarus cerberus styx (Hymenoptera, Vespidae)

In primitively eusocial insect societies, reproductive division of labor is established by dominance-submission interactions which determine a linear dominance hierarchy. As previously observed for other species, in Mischocyttarus cerberus styx (Hymenoptera, Vespidae), the dominant female is the main egg layer. Most of her attacks were to the females directly beneath in the rank establishing a hierarchy. During the pre-emergence stage, the hierarchy was already defined and in the post-emergence stage, pre-male substage, the frequency of dominance interactions were strong but the hierarchy was still maintained by the first-ranked female. In the decline stage there were many neutral individuals which could be the reproductives of a new colony.

A method for rearing immature stages of Apis melifera outside the colony (Hymenoptera: Apidae)

The objective this work is to define an effective method for following the development of immatures of Apis mellifera from metamorphosis to the emergence of the adult, under conditions allowing the application of diverse treatments. The results showed the best method to be when broods with 5th instar larvae and prepupae were maintained in incubators with the temperature and humidity controlled at 34°C and 65 to 70% respectively.

Influence of the colony cycle on physiological and morphological caste variation in the perennial neotropical swarm-founding social wasp, Protonectarina sylveirae (Hymenoptera, Vespidae, Epiponini)

This paper describes the influence of the colony cycle on caste differences in Protonectarina sylveirae. Despite invariably keeping the main aspects of the conspicuous dimorphism between the castes, it is shown that: 1- queen-worker differences varied according to the progress of the colony cycle, 2- queens in pre-emergence colonies were smaller than those in male-producing ones, 3- workers were larger in pre-emergence than in other colony stages, 4- at particular steps of the colony cycle, non-inseminated ovary-developed queens and workers were detected. The size of the spermatheca differed between inseminated and non-inseminated queens with the highest values appearing in those bearing the most developed kind of ovary development. Differences between inseminated and non-inseminated queens were found in tergites III and IV, ovarian development and amount of fatty tissues. Because tergite size relates to gaster size, this character may be an important stimulus for selection of larger queens in the course of the colony cycle.

Dominance hierarchy in different stages of development in colonies of the primitively eusocial wasp Mischocyttarus cassununga (Hymenoptera, Vespidae)

Seven colonies of Mischocyttarus cassununga were studied under field conditions at Universidade Federal de Juiz de Fora, MG, in southeastern Brazil: in pre-emergence, post-emergence and decline stages, during 145.8 hours. Dominance interactions among the females were quantified to verify the dynamics of succession in the social hierarchy of the colonies. Early pre-emergence colonies present more intense aggressive interactions than late pre-emergence ones, because the females are engaged in securing the role of main egg layer in the nest. In post-emergence (pre-male) colonies the dominance hierarchy is more defined and the frequency of dominance and subordination behaviors were lower than in pre-emergence stages: most of the agonistic behaviors are restricted to the first ranked females (potentially queens) and the subordinate individuals play the role of workers in the nests. In the post-emergence, post-male, and decline stages the hierarchy is still maintained by the aggressive behaviors of the 1st-ranked female but because the presence of males and future nest foundresses these interactions are not well defined in a linear way.

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.

Ghost-ant: Post-embryonic development of the worker caste of Tapinoma melanocephalum (hymenoptera: Formicidae)

This study examines some aspects of the basic biology of the worldwide distributed ant Tapinoma melanocepbalum Fabricius. The number of larval instars and the growth ratio between each instar are given. We used colonies containing only queens and workers, and later removed these queens in order to estimate the production of eggs and the duration of immature development of the worker caste. Measurements of larvae cephalic capsule widths revealed that workers of the ghost-ant have four larval instars from egg-hatching to adult. The mean growth rate for the species is 1.38, in accordance with Dyar's rule. The highest egg production was 5.3±2.2 eggs/day/queen and the analysis of these brood suggested the presence of two kinds of eggs inside the colony. The development of workers from egg to adult lasted 16-52 days with the embryonic development longer than larval, prepupal or pupal stages. Despite the slow egg-laying by queens, our findings also showed that colonies of T. melanocephalum grow faster than colonies of other tramp ants.

Foraging behavior and colony cycle of agelaia vicina (Hymenoptera: Vespidae; Epiponini)

The neotropical Agelaia vicina has the largest nest built among social wasps, yet little is known about nest construction, growth and structure. In this work, the development of two nests of A. vicina was followed. Studies were done through analysis of images to estimate the growth of nests. The material collected below the nests was examined to estimate colony productivity. Nests were collected to analyze their architecture and structure. Colony cycle was similar in the two colonies. Colonies increase in size throughout the dry season and into the rainy season, with a sudden drop in production at the end of the rainy season. The colonies doubled in size in about six months.

Dynamics of DNA Methylation during Early Development of the Preimplantation Bovine Embryo

There is species divergence in control of DNA methylation during preimplantation development. The exact pattern of methylation in the bovine embryo has not been established nor has its regulation by gender or maternal signals that regulate development such as colony stimulating factor 2 (CSF2). Using immunofluorescent labeling with anti-5-methylcytosine and embryos produced with X-chromosome sorted sperm, it was demonstrated that methylation decreased from the 2-cell stage to the 6-8 cell stage and then increased thereafter up to the blastocyst stage. In a second experiment, embryos of specific genders were produced by fertilization with X- or Y-sorted sperm. The developmental pattern was similar to the first experiment, but there was stage × gender interaction. Methylation was greater for females at the 8-cell stage but greater for males at the blastocyst stage. Treatment with CSF2 had no effect on labeling for DNA methylation in blastocysts. Methylation was lower for inner cell mass cells (i.e., cells that did not label with anti-CDX2) than for trophectoderm (CDX2-positive). The possible role for DNMT3B in developmental changes in methylation was evaluated by determining gene expression and degree of methylation. Steady-state mRNA for DNMT3B decreased from the 2-cell stage to a nadir for D 5 embryos >16 cells and then increased at the blastocyst stage. High resolution melting analysis was used to assess methylation of a CpG rich region in an intronic region of DNMT3B. Methylation percent decreased between the 6-8 cell and the blastocyst stage but there was no difference in methylation between ICM and TE. Results indicate that DNA methylation undergoes dynamic changes during the preimplantation period in a manner that is dependent upon gender and cell lineage. Developmental changes in expression of DNMT3B are indicative of a possible role in changes in methylation. Moreover, DNMT3B itself appears to be under epigenetic control by methylation. © 2013 Dobbs et al.

Algoritmos de alinhamento múltiplo e técnicas de otimização para esses algoritmos utilizando Ant Colony

Pós-graduação em Ciência da Computação - IBILCE

Development of twenty-one polymorphic microsatellite markers for the fungus-growing ant, Mycocepurus goeldii (Formicidae: Attini), using Illumina paired-end genomic sequencing

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