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.

Ultrastructural and Cytochemical Aspects of Metamorphosis in the Midgut of Apis mellifera L. (Hymenoptera: Apidae: Apinae)

The midgut of Apis mellifera is remodeled during metamorphosis. The epithelium and, to a lesser extent, the muscular sheath degenerate between the end of the last larval instar and the onset of pupation (prepupa).The larval epithelium is shed to the midgut lumen and digested, while a new epithelium is reconstructed from larval regenerative cells. During pupation, some reorganization still occurs, mainly in brown-eyed pupae. In pharate adult, the midgut wall shows the characteristics of adult, although some cells have pycnotic nuclei. The localization of alkaline and acid phosphatases showed that these enzymes were not involved in the reabsorption of the midgut wall.

Comparative study of the cuticular hydrocarbon composition of Melipona bicolor Lepeletier, 1836 (Hymenoptera, Meliponini) workers and queens

In social insects, cuticular hydrocarbons are involved in species, kin, caste and nestmate recognition. Gas chromatography and mass spectrometry were used to compare the cuticular hydrocarbon composition of workers, males and queens of Melipona bicolor. The cuticular hydrocarbon composition of this species was found to consist mainly of C23, C25:1, C25, C27:1, C27, C29:1 and C29, which are already present in imagoes that have not yet abandoned the brood cell. This composition varied quantitatively and qualitatively between and within the castes and sexes. The newly emerged workers and young queens (virgins) had similar cuticular hydrocarbon profiles, which were different from those of the males. When the females start executing their tasks in the colony, the cuticular hydrocarbon profile differences appear. The workers have less variety, while the queens conserve or increase the number of cuticular hydrocarbon compounds. The queens have more abdominal tegumentary glands than the workers, which apparently are the source of the new cuticular compounds.

Is the number of antennal plate organs (sensilla placodea) greater in hygienic than in non-hygienic Africanized honey bees?

Hygienic behavior is a desirable trait in honey bees (Apis mellifera L.), as hygienic bees quickly remove diseased brood, intermpting the infectious cycle. Hygienic lines of honey bees appear to be more sensitive to the odors of dead and diseased honey bee brood, and Africanized honey bees are generally more hygienic than are European honey bees. We compared the number of sensilla placodea, antennal sensory structures involved in the perception of odor, in 10 bees from each of six hygienic and four non-hygienic colonies of Africanized honey bees. The sensilla placodea of three of the terminal segments (flagellomeres) of the right antenna of each bee were counted with a scanning electron microscope. There were no significant differences in the mean numbers of sensilla placodea between the hygienic and non-hygienic bees, though the variance was higher in the hygienic group. Flagellomere 4 had significantly more sensilla placodea than flagellomeres 6 and 8. However, there was no significant difference between the other two flagellomeres. As hygienic bees are capable of identifying dead, injured, or infested brood inside a capped brood cell, sensilla placodea probably have an important role in enabling worker bees to sense sick brood. However, we did not find greater numbers of this sensory structure in the antennae of hygienic, compared to non-hygienic Africanized honey bees.

Electrophoretical Protein Profile in Apis mellifera (Hymenoptera; Apidae) Hypopharyngeal Glands under Juvenile Hormone Effect When the Colony is Grown in the Absence of Brood

Twelve-day-old and 25-day-old Apis mellifera workers were treated or not treated with juvenile hormone at the moment of emergence and reared in the colony without brood. Having the brood interference apart, the hormone effect on the hypopharyngeal glands protein expression was determined through the electrophoretical protein profiles of the both groups of bees. In those conditions, the hormone induced changes that were different from the control. Protein bands of 66 and 48 kDa were intensified in the 12-day-old bees, whereas band of 42 kDa was reduced in the 25-day-old bees. That indicated a different effect of the juvenile hormone in the function of bee aging, which promoted a glandular protein activation in the young bees and, in contrast, an inhibitory action in the 25-day-old bees workers.

Chemical composition of the dufour gland secretion in queens of Melipona bicolor (Hymenoptera, Meliponini)

We describe differences in the chemical composition of the Dufour gland secretion of virgin and physogastric queens of Melipona bicolor through gas chromatography and mass spectrometry. The Dufour gland secretion of virgin queens consists only of hydrocarbons, while that of physogastric queens contains, besides these, a variety of other compounds, such as isobutyrate and acetate esters. Such differences may indicate the queen fecundity condition and the oxygenated compounds of the physogastrics secretion may help to increase their attractiveness.

Atividade anti Staphylococcus aureus de extratos de própolis (EP) de Apis mellifera preparados com diferentes concentrações de etanol

Propolis has been used in folk medicine and possesses a broad spectrum of biological activities, specially antibacterial activity. Studies have demonstrated that the composition of propolis extract may have influence in such activity. The goal of this study was to investigate the antibacterial activity of eleven propolis extracts (PE) against sixty one Staphylococcus aureus strains, isolated from newborn clinical specimens. The PE from Apis mellifera were prepared by using pure water and mixtures of water with ethanol at different concentrations (from 0 to 100%), 25g of propolis in 100 mL of solvent, and three days of maceration followed by filtration. Determination of Minimal Inhibitory Concentration (MIC) by agar dilution method was performed and serial concentrations from each PE were achieved (%v/v) in plates containing Mueller Hinton agar. It was possible to verify that the anti S. aureus activity was directly proportional to ethanol concentration and no significant differences were observed among PE with ethanol concentration from 70 to 100%. The MIC 90% values ranged from 0.4 to 0.6% (v/v) and the 70% ethanolic extract were the most efficient to inhibit bacterial growth (MIC 90%=0.42%, v/v). In conclusion, our results suggest that the EP composition and, consequently, the concentration of ethanol used as solvent may influence the antibacterial activity of propolis from A. mellifera.

Macromolecular array patterns of silk gland secretion in social Hymenoptera larvae

The cocoon, produced by most holometabolous insects, is built with silk that is usually produced by the larval salivary gland. Although this silk has been widely studied in the Lepidoptera, its composition and macromolecular arrangement remains unknown in the Hymenoptera. The macromolecular array patterns of the silk in the larval salivary gland of some meliponids, wasps, and ants were analyzed with polarized-light microscopy, and they were compared with those of Bombyx mori (Lepidoptera). There is a birefringent secretion in the glandular lumen of all larvae, due to filamentous structural proteins that display anisotropy. The silk in the distal, middle and proximal regions of the secretory portion of Formicidae and Vespidae glands presented a lattice optical pattern. We found a different pattern in the middle secretory portion of the Meliponini, with a zigzag rather than a lattice pattern. This indicates that the biopolymer fibers begin their macromolecular reorganization at this glandular region, different from the Formicidae and the Vespidae, in which the zigzag optical pattern was only found at the lateral duct. Probably, the mechanism of silk production in the Hymenoptera is a characteristic inherited from a common ancestor of Vespoidea and Sphecoidea; the alterations in the pattern observed in the Meliponini could be a derived characteristic in the Hymenoptera. We found no similarity in the macromolecular reorganization patterns of the silk between the Hymenoptera species and the silkworm.

Effect of Brazilian propolis on experimental hepatotoxicity in rats

Propolis (bee glue) is one of the major hive products of bees and is rich in flavonoids, which are known for their antioxidant activities. The aim of this study was to evaluate the hepatoprotective effects of the ethanolic extract of propolis (EEP) against experimental carbon tetrachloride (CCl 4)-induced liver toxicity in rats by means of biochemical indices. The animals were divided into 4 groups: GI= received mineral oil; GII= CCl 4(4mL/kg; Lp., single dose) treated; GIII= CCl4 (4mL/kg; i.p., single dose) treatment followed by ethanolic extract of propolis (100mg/kg) for gavage from the species Tetragonisca angustula, daily for 3 days and GIV= CCl4 (4mL/kg; i.p., single dose) treatment followed by ethanolic extract of propolis (100mg/kg) for gavage from the species Nannotrigonea testaceicornes, daily, for 3 days. The serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), cholesterol and triacylglycerols were estimated after 3 days. CCl 4 caused a maximum increase (p<0,01) above biochemical parameters. As compared to CCl4 group (GII), the EEP (GIII and GIV) showed reduction in cholesterol, triacylglycerol, ALT, AST and alkaline phosphatase activity in the serum. In conclusion, these data indicate that EEP improved the dyslipidaemia, moreover, significantly attenuated increases in serum ALT and AST activities in rats with liver damage induced by carbon tetrachloride.

Enzymatic variability among venoms from different subspecies of Apis mellifera (Hymenoptera: Apidae)

The enzymatic variability was analyzed in venom extracts from bees reared in different colonies of the Africanized, A. m. ligustica and A. m. carnica subspecies. The implications of this variation focused on the biochemistry differentiation and immunogenicity of these venoms. The results showed the existence of a huge variability among the subspecies as well as among the colonies for three out of the six tested components - hyaluronidase, acid phosphatase and proteases - suggesting the utilization of these features as possible biochemical markers. Furthermore, although not statistically significant, it was found that the Africanized bee venom presented slightly higher levels of protein content and esterase activity, when compared to the other subspecies. If the esterase plays a role in the pain intensity caused by the sting, as suggested elsewhere, this might suggest a reason for a bigger algogenicity of this venom in relation to that of European bees. On the other hand, A. m. ligustica bees presented the highest levels of proteolytic and acid phosphatase activities, whose functions are not enlightened in Hymenoptera venoms. The A. m. carnica workers presented the highest hyaluronidase and the lowest acid phosphatase activity levels. The extremely variable results among colonies of the same subspecies and among subspecies, for the tested venom components, justify the absence of correlation between allergic reactions and tests with pooled venom.

Ultramorphology and histology of the venom gland of workers of Apis mellifera (Hymenoptera, Apidae) before and after an electrical shock treatment

This paper describes the ultramorphology and histology of the venom reservoir in 14-day old workers of Apis mellifera, immediately before and after the application of electrical shocks with the object of causing venom elimination and reservoir collapse. The external epithelial surface of the reservoir was differentiated according to its morphological aspects into posterior, median, and proximal or duct regions at the ventral surface and into anterior and posterior regions at the dorsal surface. While the epithelium of the proximal region forms a ventral infolding, a dorsal salience is formed at this region. These structures and the epithelial regions persist both in full and empty reservoirs. The reservoir appeared full and distended before the electrical shocks were applied and became empty and withered afterwards due to the elimination of the secretion, without any reductions in length. Nevertheless, some secretion was kept inside the lumen, thus suggesting a possible role for the reservoir in the modification of the secretion.

Hydrolases in the hypopharyngeal glands of workers of Scaptotrigona postica and Apis mellifera (Hymenoptera, Apinae)

Hydrolytic enzymes from hypopharyngeal gland extracts of newly emerged, nurse and foraging workers of two eusocial bees, Scaptotrigona postica, a native Brazilian stingless bee, and the Africanized honey bee (Apis mellifera) in Brazil, were compared. The hypopharyngeal gland is rich in enzymes in both species. Fifteen different enzymes were found in the extracts, with only a few quantitative differences between the species. Some of the enzymes present in the extracts may have intracellular functions, while others seem to be digestive enzymes. Scaptotrigona postica, had lower β-glucosidase and higher lipase esterase activities than A. mellifera. The differences may be due to different feeding habits and behavioral peculiarities of the two species. ©FUNPEC-RP.

Africanized honeybees: Biological characteristics, urban nesting behavior and accidents caused in Brazilian cities (Hymenoptera: Apidae)

In 1956 African honeybee queens (Apis mellifera scutellata) were imported from South Africa and Tanzania to Brazil, as part of a government project to increase Brazilian honey production. The European honeybees existing in that country had not adapted well to the tropical conditions and consequently, had a low productivity. The newly introduced bee was known to produce substantially more honey than the other subspecies, but was also famous for its great aggressiveness and quicker attack of intruders with less disturbance. Hoping to create a new hybrid bee that would be both docile and productive, the scientist Warwick Estevam Kerr tried to cross the African and the European subspecies under controlled conditions. However, an accident resulted in the escape of 26 swarms into the Brazilian countryside, where their queens mated with drones of the European resident honeybees. The poly-hybrid bees resulting from these crossings expressed scutellata-like reproductive, foraging, and defensive behaviors and, for this reason, were called Africanized honeybees. They spread rapidly from the introduction area of the African honeybees (near Rio Claro, São Paulo state) to as far south as mid-Argentina and to the north of Texas, also settling in Arizona, New Mexico, California and Nevada, due to their high adaptability to variable ecological conditions. In spite of a few undesirable behaviors, these bees have been invoking larger economic interest because they produce much more honey, have good resistance to diseases and are excellent pollinators. In Brazil, because people frequently disturb the environment, the occupation of urban refuges by Africanized honeybees has been increasing in the last years. The concern with accidents is generally associated with the high swarming frequency recorded during the year and the variety of shelters available in urban areas. This paper deals with the biological characteristics of the Africanized honeybees, their nesting behavior in urban environments, and accidents caused by these bees in Brazilian cities.

Influence of the collection methodology on the Apis mellifera venom composition: Peptide analysis

Differences of venom peptide composition as function of two collection methodologies, electrical stimulation (ES) and reservoir disruption (RD), were analyzed by reverse-phase HPLC in Apis mellifera races - A. m. adansonii, A. m. ligustica and Africanized honeybee. The analyses were performed through determination of the relative number and percentage of each molecular form associated to the peaks eluted by chromatography. Comparison of these profiles revealed qualitative and quantitative differences related to the venom collection methodology as well to the three races analyzed. In contrast to data usually found for venom proteins, the three races presented a major number of peaks or molecular forms when venom was collected by ES. Besides, in general, the relative concentration of each peak was higher for ES in relation to RD. That indicates the presence of molecular precursors in the venom obtained by RD. The presence/absence pattern of the peaks, such as their relative concentrations showed a closer similarity between A. m. adansonii and the Africanized honeybees than that observed between these and A. m. ligustica. The obtained data allowed a discussion about the differences in the relative concentration of each venom component according to the collection methodology, and finally the biological action of the venom in different races. So, these results, apart from being useful to establish a peptide profile for each bee race as a function of the venom collection methodology, pointed out once more that the chromatographic techniques are a great tool for the identification of A. mellifera subspecies.

Effects of propolis from Brazil and Bulgaria on Salmonella serovars

Propolis shows biological properties such as antibacterial action. This bee product has a complex chemical composition, which depends on the local flora where it is produced. Salmonella serovars are responsible for human diseases that range from localized gastroenteritis to systemic infections. The aim of the present study was to investigate the susceptibility of Salmonella strains, isolated from food and infectious processes, to the antibacterial action of Brazilian and Bulgarian propolis, as well as to determine the behavior of these bacteria, according to the incubation period, in medium plus propolis. Dilution of ethanolic extract of propolis in agar was the used method. Brazilian and Bulgarian propolis showed an antibacterial action against all Salmonella serovars. The minimal inhibitory concentrations (MIC) of propolis were similar, although they were collected in different geographic regions. Salmonella typhimurium, isolated from human infection, was more resistant to propolis than Salmonella enteritidis.