Occurrence and morphometry of the hypopharyngeal glands inScaptotrigona postica Lat. (Hymenoptera, Apidae, Meliponinae)

As compared toApis mellifera where only workers have hypopharyngeal glands, inScaptotrigona postica, these glands occur in workers, queens and males. They are composed of two long axial ducts with many unicellular secretory alveoli interconnected by secretory canaliculi. The axial ducts are longer in males than in workers, but the alveolar areas of queens and males are generally smaller. In workers the alveoli have their greatest size in the nurses or middle-aged individuals while in queens and males they are larger in newly emerged individuals. The results indicate that the glands in workers may produce food for the brood as inA. mellifera, since they are well developed in the nurse workers. However, the function of the glands in queens and males remains to be clarified since these individuals have no part in brood care.     

Morphology of the fifth sternal glands of Neotropical social wasps (Hymenoptera,Vespidae, Polistinae)

Glands play a central role in the social behavior of insects, and comparative analysis of their structure may provide insights about their evolution and their role in insect social biology. Here, we describe the glands of the fifth metasomal sternite of ten polistine wasps with different social behaviors. The glands of foragers of these species were studied using semithin sections of Araldite‐embedded tissue, and scanning electron microscopy. The structure of the glands observed was mostly similar to what has previously been reported for independent‐founder and swarm‐founder species, respectively. Scale‐shaped modifications in the fifth sternite are reported for the first time for members of the genera Synoeca and Epipona. Two previously unreported glands in the fifth sternite are also described. A more restrictive definition of the name Richards' gland is proposed, applying to the class 3 cells associated with scale modifications of the fifth sternite, based on structural differences between the glands observed, homology requirements, and functional evidence. Previous phylogenetic reconstructions of this character suggest that it appeared early in the Vespidae and disappeared four times, with a single reappearance in the genus Vespula. The restricted definition of Richards' gland suggests that this structure is an exclusive trait of the Epiponini, with two reversals.     

Modes of cell death in the hypopharyngeal gland of the honey bee (Apis mellifera l)

Different modes of cell death have been revealed in the regressing hypopharyngeal glands of worker honey bees. The hypopharyngeal gland, which is well developed in young nursing bees to produce protein for larval food, was seen to regress naturally in foraging adult worker bees. A range of techniques including histology, cytochemistry, in situ TUNEL, Annexin V and Comet assays indicated that cells within the gland demonstrate progressive symptoms of apoptosis, necrosis and a vacuolar form of programmed cell death. The latter mode of cell death did not display chromatin margination, but was accompanied by an enhanced level of autophagic and hydrolytic activity in which a cytosolic source of acid phosphatase became manifest in the extra-cisternal spaces. Normal and annexin-positive cells were found to occur in the younger nursing bees, whilst necrosis and an aberrant vacuolar type of apoptosis predominated in the older foraging bees. The relevance of these results to the classification of programmed cell death is discussed.     

Influence of age and caging upon protein metabolism,hypopharyngeal glands and trophallactic behavior in the honey bee (Apis mellifera L.)

Summary Different-aged honey bees were either kept in a cage together with young sisters for eight days or lived in their colony. Following an injection of¹⁴C-phenylalanine (Phe) we measured incorporation of¹⁴C-Phe into head protein and total protein, as well as the size of the hypopharyngeal glands. While confined in a cage for four hours, injected bees (from colony or cage) dispensed the¹⁴C-labelled protein-rich products of their hypopharyngeal glands to recipients. Eight-day-old colony bees had well developed hypopharyngeal glands, whereas at the age of sixteen days the glands had already decreased in size. Young caged bees had smaller hypopharyngeal glands. Colony bees had higher incorporation rates into total protein and head protein than bees living in a cage. Bees of different age classes, irrespective of caging, fed the same number of recipients; but the amount of¹⁴C-labelled protein-rich jelly distributed by caged bees was significantly smaller than that distributed by colony bees. Our results indicate that trophallaxis between young donor workers and newly emerged recipient worker bees is not the key factor for regular development and activity of the hypopharyngeal glands.Dedicated to Achim Lass's daughter Katrin.     

Lipolytic, Proteolytic, and Cholesterol-Degrading Bacteria from the Human Cerumen

Cerumen, also known as ear wax, is a yellowish waxy substance secreted from specialized glands in the ear canal of mammals. Human cerumen is rich in protein (mainly keratin), lipids (long-chain fatty acids), alcohols, squalene, and cholesterol. To-date the role of cerumen is not totally clear but it is believed to have antimicrobial properties. Here we describe the isolation of multiple bacterial species from human cerumen (among them many Staphylococcus spp. and, interestingly, multiple Bacillus spp.) showing that many of these bacteria harbor biochemical traits enabling them to utilize different cerumen components for their growth. We also suggest the existence of microbial consortia.     

The fungal α‐aminoadipate pathway for lysine biosynthesis requires two enzymes of the aconitase family for the isomerization of homocitrate to homoisocitrate

Fungi produce α‐aminoadipate, a precursor for penicillin and lysine via the α‐aminoadipate pathway. Despite the biotechnological importance of this pathway, the essential isomerization of homocitrate via homoaconitate to homoisocitrate has hardly been studied. Therefore, we analysed the role of homoaconitases and aconitases in this isomerization. Although we confirmed an essential contribution of homoaconitases from Saccharomyces cerevisiae and Aspergillus fumigatus, these enzymes only catalysed the interconversion between homoaconitate and homoisocitrate. In contrast, aconitases from fungi and the thermophilic bacterium Thermus thermophilus converted homocitrate to homoaconitate. Additionally, a single aconitase appears essential for energy metabolism, glutamate and lysine biosynthesis in respirating filamentous fungi, but not in the fermenting yeast S. cerevisiae that possesses two contributing aconitases. While yeast Aco1p is essential for the citric acid cycle and, thus, for glutamate synthesis, Aco2p specifically and exclusively contributes to lysine biosynthesis. In contrast, Aco2p homologues present in filamentous fungi were transcribed, but enzymatically inactive, revealed no altered phenotype when deleted and did not complement yeast aconitase mutants. From these results we conclude that the essential requirement of filamentous fungi for respiration versus the preference of yeasts for fermentation may have directed the evolution of aconitases contributing to energy metabolism and lysine biosynthesis.     

Comparing the secretory pathway in honeybee venom and hypopharyngeal glands

We provide insights into the secretory pathway of arthropod gland systems by comparing the royal jelly-producing hypopharyngeal glands and the venom-producing glands of the honeybee, Apis mellifera. These glands have different functions and different product release characteristics, but both belong to the class 3 types of insect glands, each being composed of two cells, a secretory cell and a microduct-forming cell. The hypopharyngeal secretory cells possess an extremely elongate tubular invagination that is filled with a cuticular structure, the end-apparatus, anchored against the cell membrane by a conspicuous series of actin rings. In contrast, venom glands have no actin rings, but instead have an actin-rich brush border surrounding the comparatively short and narrow end-apparatus. We relate these cytoskeletal differences to the production system and utilisation of secretions; venom is stored in a reservoir whereas royal jelly and enzymes are produced on demand. Fluorescence-based characterisation of the actin cytoskeleton combined with scanning electron microscopy of the end-apparatus allows for detailed characterisation of the point of secretion release in insect class 3 glands.     

Morphology of the sternal and tergal glands producing the sexual pheromones and the aphrodisiacs among the cockroaches of the subfamily oxyhaloinae

Among cockroaches in the subfamily of Oxyhaloinae, the adult males produce two essential and successively active chemical signals: the sex pheromone attracting females from a distance secreted by the sternal glands, and the aphrodisiac required for mating which is secreted by the tergal glands. The adult males of the seven species studied, Nauphoeta cinerea, Henschoutedenia flexivitta, Leucophaea maderae, Jagrehnia madecassa, Gromphadorhina portentosa, G. laevigata, and G. chopardi, possess well-developed sternal and tergal glands whose number varies according to the species and methods of mating (three to six sternal glands and four to seven tergal glands). These glands are basically composed of type three glandular units (glandular cell + duct cell) and type 2 cells (modified oenocytes) which exhibit no significant external cuticular modification except for tergite 2 of L. maderae. The extreme variance in development of these glands can be linked to sexual behavior. The hypothesis put forward here is that of a regressive evolution of the tergal glands, related to a modification of the role played by the aphrodisiacs which they secrete.     

Trap gland morphology and its systematic implications in Taiwan Utricularia (Lentibulariaceae)

The highly specialized trap glands of carnivorous plant are responsible for the digestion and absorption of the prey; however, there are few studies on their systematics and evolution. In this study, the gland morphology of six carnivorous plant species of the genus Utricularia (Lentibulariaceae) in Taiwan, including U. aurea Lour., U. australis R. Br., U. bifida L., U. caerulea L., U. gibba L. and U. striatula Sm., was examined with a scanning electron microscope. The glands on both the outer and inner surfaces of the traps were examined. We found that the external glands had little diagnostic value, but the internal glands could be used in the identification of Taiwan species. Evolutionary trends of gland characteristics are discussed, analyzing morphology of the internal glands, based on previous work. A new hypothesis for the evolution of internal gland structure in Utricularia is also proposed.     

Honeybee glands as possible infection reservoirs of Nosema ceranae and Nosema apis in naturally infected forager bees

Aims: To determine whether Nosema ceranae and Nosema apis are present in different gland tissues of honeybee, Apis mellifera L. and to monitor spore presence and quantity in these glands in naturally infected hives from July 2009 to July 2010 in Quebec, Canada. Methods and Results: Nosema spp. were quantified using duplex quantitative real‐time PCR in the thoracic salivary, hypopharyngeal, mandibular glands, and venom sac and glands of A. mellifera over a period of 8 months. Both Nosema species were present in all the glands as single or mixed species; however, N. apis was not present as single‐species detections in the salivary glands (see Table 2). Nosema ceranae was more prevalent throughout the 8 months. Significant correlative relationships were established for N. ceranae and N. apis levels in the honeybee glands and those found within the intestines of forager honeybees. Overall, the seasonality of N. ceranae and N. apis in the different glands tightly followed the seasonal patterns in the honeybee guts. Conclusions: Nosema ceranae and N. apis are not tissue specific, and honeybee glands have potential to become a useful indicator of the extent of disease in the colony and may represent a potential infection reservoir. Significance and Impact of the Study: First report of spore load quantification of Nosema spp. in different honeybee glands.     

Monitoring circadian rhythms of individual honey bees in a social environment reveals social influences on postembryonic ontogeny of activity rhythms

Social factors constitute an important component of the environment of many animals and have a profound influence on their physiology and behavior. Studies of social influences on circadian rhythms have been hampered by a methodological trade-off: automatic data acquisition systems obtain high-quality data but are effective only for individually isolated animals and therefore compromise by requiring a context that may not be sociobiologically relevant. Human observers can monitor animal activity in complex social environments but are limited in the resolution and quality of data that can be gathered. The authors developed and validated a method for prolonged, automatic, high-quality monitoring of focal honey bees in a relatively complex social environment and with minimal illumination. The method can be adapted for studies on other animals. The authors show that the system provides a reliable estimation of the actual path of a focal bee, only rarely misses its location for > 1 min, and removes most nonspecific signals from the background. Using this system, the authors provide the first evidence of social influence on the ontogeny of activity rhythms. Young bees that were housed with old foragers show ~24-h rhythms in locomotor activity at a younger age and with stronger rhythms than bees housed with a similar number of young bees. By contrast, the maturation of the hypopharyngeal glands was slower in bees housed with foragers, similar to findings in previous studies. The morphology and function of the hypopharyngeal glands vary along with age-based division of labor. Therefore, these findings indicate that social inhibition of task-related maturation was effective in the experimental setup. This study suggests that although the ontogeny of circadian rhythms is typically correlated with the age-based division of labor, their social regulation is different.     

Unusual labial glands in snakes of the genus Geophis Wagler, 1830 (Serpentes: Dipsadinae)

Geophis belongs to the goo‐eating dipsadine assemblage of snakes that are known to feed exclusively on earthworms, snails, and slugs. Although the unusual feeding strategies of the goo‐eating dipsadines are well known (but poorly documented), little attention has been paid to their internal anatomy. Here, we describe a new and noteworthy morphological and histochemical condition of the infralabial glands in three species of Geophis (G. brachycephalus, G. nasalis and G. semidoliatus), all earthworm feeders. Their infralabial glands are constituted of two distinct parts: an anterolateral portion composed of mucous and seromucous cells that stretches from the tip of the dentary to the corner of the mouth, and a tubular posteromedial portion that is exclusively seromucous. The anterolateral portion receives fibers of the levator anguli oris muscle that attaches on its posterodorsal extremity while the posteromedial portion extends posteriorly to the corner of the mouth where it receives fibers of the adductor mandibulae externus medialis muscle. Furthermore, the posteromedial portion of the infralabial gland is constituted by large acini filled with secretion that is periodic acid‐Schiff positive. These acini release their secretion directly into a large lumen located in the middle of the glandular portion. In the three species examined, the supralabial glands show a traditional configuration, being constituted of mucous and seromucous cells and retaining an enlarged part in its caudal region that resembles a Duvernoy's gland. The presence in Geophis of an expanded lumen in part of the infralabial gland that is compressed by an adjacent muscle suggests a more specialized role for the secretion produced by these glands that may not be related to envenomation but rather to prey transport and mucus control. J. Morphol. 275:87–99, 2014. © 2013 Wiley Periodicals, Inc.     

Multiple mating and offspring quality in <Emphasis Type="Italic">Lasius</Emphasis> ants

Genetic diversity benefits for social insect colonies headed by polyandrous queens have received intense attention, whereas sexual selection remains little explored. Yet mates of the same queen may engage in sperm competition over the siring of offspring, and this could confer benefits on queens if the most successful sire in each colony (the majority sire) produces gynes (daughter queens) of higher quality. These benefits could be increased if high-quality sires make queens increase the percentage of eggs that they fertilize (unfertilized eggs develop into sons in social hymenopterans), or if daughters of better genetic quality are over-represented in the gyne versus worker class. Such effects would lead to female-biased sex ratios in colonies with high-quality majority gynes. I tested these ideas in field colonies of Lasius niger black garden ants, using body mass of gynes as a fitness trait as it is known to correlate with future fecundity. Also, I established the paternity of gynes through microsatellite DNA offspring analyses. Majority sires did not always produce heavier gynes in L. niger, but whenever they did do so colonies produced more females, numerically and in terms of the energetic investment in female versus male production. Better quality sires may be able to induce queens to fertilize more eggs or so-called caste shunting may occur wherever the daughters of better males are preferentially shunted to into the gyne caste. My study supports that integrating sexual selection and social evolutionary studies may bring a deeper understanding of mating system evolution in social insects.     

Sticky predators: a comparative study of sticky glands in harpactorine assassin bugs (Insecta: Hemiptera: Reduviidae)

Zhang, G. and Weirauch, C. 2011. Sticky predators: a comparative study of sticky glands in harpactorine assassin bugs (Insecta: Hemiptera: Reduviidae). —Acta Zoologica (Stockholm) 00 : 1–10. For more than 50 years, specialized dermal glands that secrete sticky substances and specialized setae have been known from the legs of New World assassin bugs in the genus Zelus Fabricius (Reduviidae: Harpactorinae). The gland secretions and specialized ‘sundew setae’ are involved in enhancing predation success. We here refer to this predation strategy as ‘sticky trap predation’ and the specialized dermal glands as ‘sticky glands’. To determine how widespread sticky trap predation is among Reduviidae, we investigated taxonomic distribution of sticky glands and sundew setae using compound light microscopical and scanning electron microscopical techniques and sampling 67 species of Reduviidae that represent 50 genera of Harpactorini. We found sticky glands in 12 genera of Harpactorini and thus show that sticky trap predation is much more widespread than previously suspected. The sticky glands vary in shape, size and density, but are always located in a dorsolateral position on the fore tibia. Sundew setae are present in all taxa with sticky glands with the exception of Heza that instead possesses unique lamellate setae. The sticky trap predation taxa are restricted to the New World, suggesting a New World origin of this unique predation strategy.     

Evolutionary loss of a neural pathway from the nervous system of a fly (Glossina morsitans/Diptera)

Three pairs of specialized axons found in other muscoid flies are absent in the tsetse, Glossina morsitans, which also lacks the tergotrochanteral muscle. Neither light nor electron microscopy could demonstrate any evidence for the cervical giant fiber axon, the peripherally synapsing axon, or the tergotrochanteral motor axon. The specialized characteristics of these axons must have been altered during the evolution of Glossina. This divergence of individual neurons from the more typical muscoid pattern not only demonstrates the evolutionary modification of specific identified cells; it may also provide an opportunity to study the ontogenetic determination of unique neuronal features.     

Extrafloral nectaries in the genus Macaranga (Euphorbiaceae) in Malaysia: comparative studies of their possible significance as predispositions for myrmecophytism

Some species of the paleotropical tree genus Macaranga (Euphorbiaceae) live in close association with ants. The genus comprises the full range of species from those not regularly inhabited by ants to obligate myrmecophytes. In Malaysia (Peninsular and Borneo) 23 of the 52 species are known to be ant-associated (44%). The simplest structural adaptation of plants to attract ants are extrafloral nectaries. We studied the distribution of extrafloral nectaries in the genus Macaranga to assess the significance of this character as a possible predisposition for the evolution of obligate myrmecophytism. All species have marginal glands on the leaves. However, only the glands of non- myrmecophytic species function as nectaries, whereas liquids secreted by these glands in myrmecophytic species did not contain sugar. Some non-myrmecophytic Macaranga and transitional Macaranga species in addition have extrafloral nectaries on the leaf blade near the petiole insertion. All obligatorily myrmecophytic Macaranga species, however, lack additional glands on the lamina. The non-myrmecophytic species are visited by a variety of different ant species, whereas myrmecophytic Macaranga are associated only with one specific ant-partner. Since these ants keep scale insects in the hollow stems, reduction of nectary production in ant-inhabited Macaranga seems to be biologically significant. We interpret this as a means of (a) saving the assimilates and (b) stabilization of maintenance of the association's specificity. Competition with other ant species for food rewards is avoided and thereby danger of weakening the protective function of the obligate ant- partner for the plant is reduced. A comparison with other euphorb species living in the same habitats as Macaranga showed that in genera in which extrafloral nectaries are widespread, no myrmecophytes have evolved. Possession of extrafloral nectaries does not appear to be essential for the development of symbiotic ant-plant interactions. Other predispositions such as nesting space might have played a more important role.     

Morphological correlates of echolocation frequency in the endemic Cape horseshoe bat, <Emphasis Type="Italic">Rhinolophus capensis</Emphasis> (Chiroptera: Rhinolophidae)

We investigated intraspecific variation in echolocation calls of the Cape horseshoe bat, Rhinolophus capensis, by comparing echolocation and associated morphological parameters among individuals from three populations of this species. The populations were situated in the center and at the western and eastern limits of the distribution of R. capensis. The latter two populations were situated in ecotones between vegetation biomes. Ecotone populations deviated slightly from the allometric relationship between body size and peak frequency for the genus, and there was no relationship between these variables within R. capensis. Nasal chamber length was the best predictor of peak frequency but not correlated with body size. The evolution of echolocation thus appears to have been uncoupled from body size in R. capensis. Furthermore, females used higher frequencies than males, which imply a potential social role for peak frequency. The differences in peak frequency may have originated from random founder effects and then compounded by genetic drift and/or natural selection. The latter may have acted directly on peak frequency altering skull parameters involved in echolocation independently of body size, resulting in the evolution of local acoustic signatures.     

THE BIOLOGY OF THE SOCIAL WASPS (HYMENOPTERA, VESPIDAE)

1. After defining social wasps, an outline is given of their classification and possible evolution. The Vespidae probably arose in the Malayan region at about the beginning of the Tertiary period and spread from there all over the world. They are now highly developed in South America and it is suggested that they may have reached that country over the Behring Straits, probably in two waves, the first of an ancestral Polybiine, the second perhaps of Polistes only. 2. A biief account is given of the architecture of wasps' nests which is often specific to the genus. Nevertheless, there are examples of very similar wasps making very different nests and there does not seem any case for putting an overriding value on nest-architecture in classification. While we know sufficiently well what we have to explain, only a very small beginning has been made in describing and analysing the behaviour which produces the elaborate constructions we find. 3. In the familiar Vespinae the concepts of queen and worker are well defined and the two castes are discontinuous. In genera such as Polistes the position is much more fluid, particularly in the tropical species in which it is not necessary to have a queen specialized for hibernation. Some time after nest-production, however, a queen becomes recognizable, though often more by her behaviour than by her structure. In the Polybiini, queens and workers are sometimes well differentiated and sometimes not; but in most genera and species there is more than one queen in a nest. Other types of females not so well defined and of uncertain significance also occur. In temperate climates new colonies are founded by one or a few queens; in the tropics most colonies are founded by swarms of queens and workers. 4. The main differences between queens and workers seem to be determined in the larval stage, perhaps by some secretion administered by the adults, but clearly influenced by other factors as well. The full behavioural differences between the castes are often finally established by social interactions between the adults. 5. Males tend to be produced towards the end of the life of short-lived colonies or towards the end of the reproductive cycles of longer-lived colonies. There is need for more information about in- or out-breeding patterns, particularly in relation to specific differences in the degree of sexual dimorphism. 6. Very few pheromones are recognized with certainty and only one, the queen-substance of Vespa orientalis, has been identified chemically. However, some species produce a substance from the female sixth gastral sternite (Van der Vecht's organ) which at least in one genus is an ant-repellent. Some genera of Polybiines have a somewhat similar gland on the fifth sternite which may be connected with caste-differentiation. Some wasps (Vespula) produce a footstep pheromone concerned with the recognition of the nest entrance and there is less good evidence for the existence of significant substances in the saliva of workers and in their poison glands (alarm substance). 7. Trophallaxis, or the supply of salivary secretion by the larvae to adults more or less in exchange for the food provided from outside by the foragers, seems to be essential to the colonies of Vespa since the adults have no proteases. Trophallaxis also occurs in some Polistinae but its significance there is not known. 8. Social hierarchies of ‘peck orders’ are always established amongst the adults of Polistes and play a part in determining which of several potential queens becomes the acting one. They are also important in establishing the relations of the queen to the workers and of the latter amongst themselves. A similar hierarchy occurs in Belono-gaster. Some sort of hierarchy also exists amongst adult Vespula and is probably important in relation to trophallaxis, but the hierarchies must become less definite in large colonies with hundreds of individuals, especially if there is more than one queen. 9. The principal hurdle in the evolution of social behaviour is the establishment of genes which determine that some females lay most or effectively all of the eggs while others nurse, build and forage. This evolution may only be possible amongst females which are so closely related that their genomes are almost identical. In this connexion we need much more direct field evidence on the dispersal of queens, on mating systems and the incidence of multiple insemination. It appears that, once true social life is established, considerable diversification in nest architecture and social organization may happen relatively rapidly, probably much influenced by various ecological pressures, especially predation. 10. A number of species of Vespula, Vespa and Polistes have become social parasites, in the first and the last cases without a worker caste. This seems like a wrong turning taken in the course of the normal evolution of the queen-worker relationship. 11. A brief account is given of the attempts to provide a theoretical framework for the population dynamics of wasp-colonies. 12. An account is given of the relations of wasps, chiefly as foragers, with plants and with other animals.     

Evolution of an ornament,the dewlap,in females of the lizard genus Anolis

Male ornaments have been the subject of numerous studies on sexual selection and communication, although female ornaments have garnered substantially less study, even though female ornaments are well developed in some species. The factors that have propelled the evolution of elaborate ornaments in females are poorly understood but may include genetic correlations between the sexes, social selection, sensory drive or species recognition. We used simulation‐based comparative methods and a newly estimated phylogeny to test these four hypotheses to explain female ornamentation within the diverse neotropical lizard genus Anolis. We found support for the sensory drive hypothesis and the social selection hypothesis; the female dewlap was larger in species that use more arboreal habitats, as well as in species where the sexes were less dimorphic. We did not find support for the genetic correlation hypothesis or the species recognition hypothesis. We propose that the size of the female dewlap may evolve in response to sensory drive differentially affecting species in different habitats, as well as social selection such as male mate choice or intrasexual competition for territory among females. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 191–201.