Alterations induced by juvenile hormone in glandular cells of the Apis mellifera venom gland I - Application on the larvae (Hymenoptera: Apidae)

Histological analyses were made in order to evaluate the effects of the topic application of a synthetic juvenile hormone (JH-III Sigma) on the development of the venom glands in workers of Apis mellifera. Three experimental groups were used: the first received 1 μl of a dilution of the juvenile hormone in hexane (2μg/μl); the second group received 1 μl of hexane; and the third group, the control, did not receive any kind of treatment. The application was made on larvae at the beginning of the fifth instar and the glands were collected at different developmental stages. The results showed that the application of the diluted hormone, as well as the hexane alone, accelerated gland development in relation to the control group at all developmental stages studied. These data suggest that the juvenile hormone acts on the development of the venom gland; nevertheless, this action could be amplified by the effect of the solvent used in the present work, as well as in other studies concerning this matter.

Behavior of Atta sexdens rubropilosa (Hymenoptera: Formicidae) workers during the preparation of the leaf substrate for symbiont fungus culture

The behavioral repertory of Atta sexdens rubropilosa Forel (Hymenoptera: Formicidae) workers marked by size category was studied during the preparation of the leaf substrate in the laboratory. The workers were marked according to three physical castes, i.e., minima, generalist and forager. Seven types of behavioral acts were recorded for each caste, with the following frequencies: licking leaf fragments (64.6%), holding fragments on the surface of the fungus garden (16.4%), shredding the fragments (6.0%), chewing and crimping the edges of the fragments (9.0%), incorporating the fragments (2.7%), touching the surface of the fungus with their mandibles and other mouthparts after incorporation (0.3%), and depositing fecal fluid (0.1%). The minima workers were found to be more specialized in the activities related to the preparation of the leaf substrate, which represented 52% of the total number of tasks performed. The generalists performed 40.3% of these tasks, and the foragers 7.9%. Licking the substrate was the behavior most frequently recorded and performed for a longer period of time. In this way, the workers may feed and at the same time eliminate microorganisms that are harmful to the symbiont fungus. The smaller castes, minima and generalists, are those most responsible for the preparation of the leaf substrate and predominate within a colony. From a practical viewpoint, with the introduction of toxic bait containing insecticides, for example, these size categories will be those most intensely intoxicated, especially through the behavior of licking bait pellets. On the basis of the data obtained about these behaviors, we may raise the hypothesis that trophallaxis in not the major factor triggering contamination with an insecticide among the workers of a colony.

Chemical analysis of different larval instars and tissues of Pachycondyla (=Neoponera) villosa (Hymenoptera: Formicidae, Ponerinae)

Chemical analyses of complete larvae of the first to third instar and cuticle, fat body and salivary glands extracts of fourth instar larvae using gas chromatography and gas chromatography-mass spectrometry, were performed upon Pachycondyla villosa. The results revealed that P. villosa larvae do not produce a pheromone, as only fatty acids and n-alkanes were detected. After quantifying the identified compounds, it was determined that the fat body is the main place of storage and/or production of the cuticular hydrocarbons. It was also observed that the absolute quantity of cuticular hydrocarbons increases progressively during larval development. Inferences about the transport behavior of matured larvae to the pupation place and the colony odor are discussed.

Division of labor in Ectatomma edentatum (Hymenoptera, Formicidae)

The behavioral division of labor between queens and workers of E. edentatum was investigated under laboratory conditions. Each behavioral category of both castes was described by direct observation of the ants in the colonies. The spatial position and the behavior of each individual were recorded. A colony ethogram was constructed to determine comparatively the behavioral repertory of the 2 castes. Most of the members of the colonies, including the queens, occupied the 2nd chamber, which also contained the immature stages. Forty-two behavioral categories were recorded for the workers, and 28 for the queens. The comparison of the behavioral repertory of the 2 castes revealed that ovipositing a fecundated egg is an exclusive behavior of the queens, while the workers showed 15 exclusive behaviors. Queens were never seen foraging out of the nest. Twelve behaviors were common for both castes. Polygynic colonies have only 1 female with full-developed ovaries, which is the main egg layer of the group, a feature defining the social organization of colonies of E. edentatum as a functional monogyny.

Enzymatic activity of hypopharyngeal gland extracts from workers of Apis mellifera (Hymenoptera, Apidae, Apinae)

This research presents a comparative study of enzymatic activity of the hypopharyngeal gland extracts from workers of Apis mellifera in three physiologic stages: newly emerged, nurse and forager workers, with the objective of contributing to the comprehension of the gland function. In order to determinate the enzymes present in the extracts, the Api Zym kit (Bio Mérieux) was used to test the activity of 19 different enzymes. The enzymes found in larger amounts only in the hypopharyngeal glands from certain individuals were the following: in newly emerged workers, the N-acetyl-down double arrow sign-glucosaminidase that may be digesting the chitin of some food ingested by the bee; in forager workers, the acid phosphatase that is likely acting in authophagic processes, the a-glucosidase, in the processing of nectar into honey, and the down double arrow sign-glucosidases, in the pollen digestion.

Enzymes in the hypopharyngeal gland extracts from workers of Scaptotrigona postica (Hymenoptera, Apinae, Meliponini) related to food storing in the colony

This study reports on research of enzymes produced by the hypopharyngeal glands, which are related to food storing in the colony, from gland extracts from nurse and forager workers of S. postica. Only the presence of the saccharase was detected in the extracts from the glands of forager workers. The results were compared to the enzymatic content of similar extracts of A. mellifera taking into account the behavioral differences among the two species.

Expanded food choice as a possible factor in the evolution of sociality of Vespidae (Hymenoptera)

A recent theory suggests that economic considerations are more important than genetic ones in the emergence and maintenance of social behavior. Evolution of social behavior in wasps, thus, could be based on the development of worker castes, which increase the efficiency of brood care and energy use of the colony. If so, social wasps should collect a larger range of prey, favoring polyethism, as social behavior should increase the adaptive value of social species among wasps by increasing the range of prey accessible. We explored the literature and showed that the Eumeninae, which are mostly solitary, draw prey from significantly fewer orders of arthropods than wasps in the subfamily Vespinae and Polistinae, which are mainly social, supporting the hypothesis that social behavior may have emerged as a more efficient way to feed and care for the young by opening a wider range of food sources, increasing the amount of food and quality of care provided to the young. Two alternative explanations of this data are also discussed.

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.

Histological, histochemical and morphometric study of female corpora allata of Pachycondyla striata ants (Hymenoptera: Ponerinae)

In this study we utilized both histological/histochemical tests and morphometric/statistical tests to observe developmental differences in the corpora allata in Pachycondyla striata workers and queens ants. The general structure of corpora allata was similar between workers and queens. The differences found among the volumes was not statistically significant when the probability value was set at 5%. Although the queen corpora allata volume has been observed smaller than those of the worker and the right gland volume has been smaller than those of the left one. Differences also were observed histologically, the worker corpora allata cells showed homogeneous cytoplasm and sparse nuclear chromatin in well defined nuclei. It was the reverse in the queens, in which the corpora allata cells showed some secretory cytoplasmic vesicles and nuclei with a different morphology, i. e., from extremely large with sparse chromatin to small with condensed chromatin. Employing histochemical tests verified that the corpora allata in both castes contained large amounts of RNA and protein in the cytoplasm of their cells and an absence of polysaccharides. Differences in the lipid amounts in worker's glands were found, whereas, in the queens' corpora allata lipids always occur.

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.

The occurrence and foraging behavior of the army ant Eciton vagans dubitatum in the Itirapina area, São Paulo State, Brazil (Hymenoptera, Formicidae)

This paper discusses the occurrence of the army ant Eciton vagans dubitatum in a semi-deciduous forest, Itirapina area, São Paulo State, Brazil. Comparisons of bivouac and raiding pattern are done in relation to other subspecies of Eciton vagans.

Ultra-estrutura de glândulas abdominais tegumentares em Oxaea flavescens (Hymenoptera, Andrenidae, Oxaeinae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Mating influence in the ovary differentiation in adult queens of Apis mellifera L. (Hymenoptera, Apidae)

The present results show that in the ovarioles of a newly emerged (0 day) queen of A. mellifera only two regions may be distinguished: a proximal, short germarium and a very long distal, terminal filament. As the queen matures and gets ready for the nupcial flight, the germarium increases in lenght, advancing towered the distal end, as the terminal filament shortens. The ovarioles of queens ready to mate (6 to 8 days old) have, already one or two ovarian follicles, i.e. a very short proximal vitellarium, but a real vitellogenesis only starts after the fecundation. If the queen does not mate the ovarioles structure is disrupted (12-16 days old). In mated queen eggs the ovarioles present three differentiated regions, from the apice to the basis: a short terminal filament, a medium size germarium, and a very long basal vitellarium. As the eggs are laid, the emptied follicle collapses, degenerates and produces a corpus luteum.

Comparação entre parâmetros externos e internos de ninhos de Atta bisphaerica Forel, 1908 (Hymenoptera, Formicidae)

Six Atta bisphaerica, Forel, 1908 (Hymenoptera, Formicidae) nests were excavated with the aim of studying the relationship between area and volume of the mound, the total volume and total number of chambers in the nest. Prior to excavation, the area and the volume of refused soil in the nests were measured. During excavation, all data referring to chambers were recorded, such as: length, depth and width. The nests named A1, A2, A3, A4, A5 and A6 presented 31.16; 40.87, 67.08, 35.04, 73.48 and 18,73m 2 of mound area, respectively. The mound area did not correlate either with the volume or with the total number of chambers. The mound volume correlated significantly with the mound area, total number and total volume of chambers. The total volume of chambers was correlated with the total number of chambers.

Cell nucleus activity during post-embryonic development of Apis melliferaL. (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.