Behavioral suites mediate group-level foraging dynamics in communities of tropical stingless bees

Competition for floral resources is a key force shaping pollinator communities, particularly among social bees. The ability of social bees to recruit nestmates for group foraging is hypothesized to be a major factor in their ability to dominate rich resources such as mass-flowering trees. We tested the role of group foraging in attaining dominance by stingless bees, eusocial tropical pollinators that exhibit high diversity in foraging strategies. We provide the first experimental evidence that meliponine group foraging strategies, large colony sizes and aggressive behavior form a suite of traits that enable colonies to improve dominance of rich resources. Using a diverse assemblage of Brazilian stingless bee species and an array of artificial ""flowers"" that provided a sucrose reward, we compared species` dominance and visitation under unrestricted foraging conditions and with experimental removal of group-foraging species. Dominance does not vary with individual body size, but rather with foraging group size. Species that recruit larger numbers of nestmates (Scaptotrigona aff. depilis, Trigona hyalinata, Trigona spinipes) dominated both numerically (high local abundance) and behaviorally (controlling feeders). Removal of group-foraging species increased feeding opportunities for solitary foragers (Frieseomelitta varia, Melipona quadrifasciata and Nannotrigona testaceicornis). Trigona hyalinata always dominated under unrestricted conditions. When this species was removed, T. spinipes or S. aff. depilis controlled feeders and limited visitation by solitary-foraging species. Because bee foraging patterns determine plant pollination success, understanding the forces that shape these patterns is crucial to ensuring pollination of both crops and natural areas in the face of current pollinator declines.

Genetic structure of Partamona helleri (Apidae, Meliponini) from Neotropical Atlantic rainforest

Stingless bees of the genus Partamona are distributed from southern Mexico to southern Brazil. This genus has been subject to different approaches to solve questions concerning general biology, taxonomy, systematics and biogeography, but population studies applying molecular techniques are inexistent. We analyzed the genetic structure of P. helleri across its geographic distribution along the coastal Atlantic tropical rainforest in Brazil. Ten mtDNA haplotypes were observed in 47 colonies of P. helleri of which some were exclusive and others shared among geographic sub-groups. Statistical analysis showed high genetic differentiation between geographic areas sampled. Fragmentation of the Atlantic forest during Pleistocene glaciations is discussed as a possible cause of the present haplotype distribution and frequency.

Morphometrical, biochemical and molecular tools for assessing biodiversity. An example in Plebeia remota (Holmberg, 1903) (Apidae, Meliponini)

We see today many efforts to quantify biodiversity in different biomes. It is very important then to develop and to apply other methodologies that allow us to assess biodiversity. Here we present an example of application of three tools with this goal. We analyzed two populations of Plebeia remota from two distinct biomes that already showed several differences in morphology and behavior. Based on these differences, it has been suggested that the populations of Cunha and Prudentopolis do not represent a single species. In order to verify the existence or absence of gene flow between these two groups, we characterized the patterns of mtDNA through RFLP, the patterns of wing venation through geometric morphometry, and the cuticular hydrocarbons through gas chromatography-mass spectrometry. We used bees collected in these two locations and also from colonies which have being kept for around 9 years at Sao Paulo University. We found six different haplotypes in these specimens, of which three of them occurred exclusively in the population of Cunha and three only in the Prudentopolis population. The fact that the populations do not share haplotypes suggests no maternal gene flow between them. The two populations were differentiated by the pattern of the wing veins. They also had different mixtures of cuticle hydrocarbons. Furthermore it was shown that the colonies kept at the university did not hybridize. These two groups may constitute different species. We also show here the importance of using other methodologies than traditional taxonomy to assess and understand biodiversity, especially in bees.

Descriptive Sensory Analysis and Acceptance of Stingless Bee Honey

Stingless bee honey samples were evaluated by sensory descriptive analysis using free choice profile methodology. Appearance, flavor, and aroma were described and the data were treated with Generalized Procrustes Analysis. Individual descriptive terms ranged from 8 to 20. Plotting the samples in a bidimensional plan indicated that appearance attributes (color and viscosity) and sweet, sour and acid flavor were strongly correlated with x axis (Dimension 1) while coconut, wood, acid, sour, and sweet flavor aroma attributes were correlated with y axis (Dimension 2). The affective test was also performed and with the exception of the Melipona scutellaris honey, all the other samples showed good acceptance. Honeys that were described as sweeter and less acid were preferred by nontrained assessors, indicating that the regular consumer recognizes honey produced by Apis mellifera bee as a standard.

A molecular phylogeny of the stingless bee genus Melipona (Hymenoptera: Apidae)

Stingless bees (Meliponini) constitute a diverse group of highly eusocial insects that occur throughout tropical regions around the world. The meliponine genus Melipona is restricted to the New World tropics and has over 50 described species. Melipona, like Apis, possesses the remarkable ability to use representational communication to indicate the location of foraging patches. Although Melipona has been the subject of numerous behavioral, ecological, and genetic studies, the evolutionary history of this genus remains largely unexplored. Here, we implement a multigene phylogenetic approach based on nuclear, mitochondrial, and ribosomal loci, coupled with molecular clock methods, to elucidate the phylogenetic relationships and antiquity of subgenera and species of Melipona. Our phylogenetic analysis resolves the relationship among subgenera and tends to agree with morphology-based classification hypotheses. Our molecular clock analysis indicates that the genus Melipona shared a most recent common ancestor at least similar to 14-17 million years (My) ago. These results provide the groundwork for future comparative analyses aimed at understanding the evolution of complex communication mechanisms in eusocial Apidae. (C) 2010 Elsevier Inc. All rights reserved.

Selective preying of the sphecid wasp Trachypus boharti on the meliponine bee Scaptotrigona postica: potential involvement of caste-specific cuticular hydrocarbons

The specialist digger wasp Trachypus boharti Rubio-Espina preys exclusively on males of the stingless bee Scaptotrigona postica Latreille 1807, although the hunting attacks involve both male and worker bees of S. postica and members of its own species. To understand the mechanism of prey selection, the cuticular hydrocarbon patterns of workers and males of S. postica are analyzed in detail, and the mandibular secretion of males is examined. The cuticular profiles of males and workers are distinctively different. The major group of cuticular compounds, heptacosene isomers, is twice as abundant in workers as in males. There is no clear distinction between worker and male mandibular secretions. Such a distinct and straightforward caste-specific difference in cuticular hydrocarbons could function as a recognition cue by which T. boharti distinguishes between workers and males of S. postica.

DAILY VARIATION OF CONSTITUTIVELY ACTIVATED NUCLEAR FACTOR KAPPA B (NFKB) IN RAT PINEAL GLAND

In mammals, the production of melatonin by the pineal gland is mainly controlled by the suprachiasmatic nuclei (SCN), the master clock of the circadian system. We have previously shown that agents involved in inflammatory responses, such as cytokines and corticosterone, modulate pineal melatonin synthesis. The nuclear transcription factor NFKB, detected by our group in the rat pineal gland, modulates this effect. Here, we evaluated a putative constitutive role for the pineal gland NFKB pathway. Male rats were kept under 12 h: 12 h light-dark (LD) cycle or under constant darkness (DD) condition. Nuclear NFKB was quantified by electrophoretic mobility shift assay on pineal glands obtained from animals killed throughout the day at different times. Nuclear content of NFKB presented a daily rhythm only in LD-entrained animals. During the light phase, the amount of NFKB increased continuously, and a sharp drop occurred when lights were turned off. Animals maintained in a constant light environment until ZT 18 showed diurnal levels of nuclear NFKB at ZT15 and ZT18. Propranolol (20 mg/kg, i.p., ZT 11) treatment, which inhibits nocturnal sympathetic input, impaired nocturnal decrease of NFKB only at ZT18. A similar effect was observed in free-running animals, which secreted less nocturnal melatonin. Because melatonin reduces constitutive NFKB activation in cultured pineal glands, we propose that this indolamine regulates this transcription factor pathway in the rat pineal gland, but not at the LD transition. The controversial results regarding the inhibition of pineal function by constant light or blocking sympathetic neurotransmission are discussed according to the hypothesis that the prompt effect of lights-off is not mediated by noradrenaline, which otherwise contributes to maintaining low levels of nuclear NFKB at night. In summary, we report here a novel transcription factor in the pineal gland, which exhibits a constitutive rhythm dependent on environmental photic information. (Author correspondence: rpmarkus@usp.br)

Sympathetic outflow activates the venom gland of the snake Bothrops jararaca by regulating the activation of transcription factors and the synthesis of venom gland proteins

The venom gland of viperid snakes has a central lumen where the venom produced by secretory cells is stored. When the venom is lost from the gland, the secretory cells are activated and new venom is produced. The production of new venom is triggered by the action of noradrenaline on both alpha(1)- and beta-adrenoceptors in the venom gland. In this study, we show that venom removal leads to the activation of transcription factors NF kappa B and AP-1 in the venom gland. In dispersed secretory cells, noradrenaline activated both NF kappa B and AP-1. Activation of NF kappa B and AP-1 depended on phospholipase C and protein kinase A. Activation of NF kappa B also depended on protein kinase C. Isoprenaline activated both NF kappa B and AP-1, and phenylephrine activated NF kappa B and later AP-1. We also show that the protein composition of the venom gland changes during the venom production cycle. Striking changes occurred 4 and 7 days after venom removal in female and male snakes, respectively. Reserpine blocks this change, and the administration of alpha(1)- and beta-adrenoceptor agonists to reserpine-treated snakes largely restores the protein composition of the venom gland. However, the protein composition of the venom from reserpinized snakes treated with alpha(1)- or beta-adrenoceptor agonists appears normal, judging from SDS-PAGE electrophoresis. A sexual dimorphism in activating transcription factors and activating venom gland was observed. Our data suggest that the release of noradrenaline after biting is necessary to activate the venom gland by regulating the activation of transcription factors and consequently regulating the synthesis of proteins in the venom gland for venom production.

The Immune-Pineal Axis Stress as a Modulator of Pineal Gland Function

The temporal organization of mammals presents a daily adjustment to the environmental light/dark cycle. The environmental light detected by the retina adjusts the central clock in the suprachiasmatic nuclei, which innervate the pineal gland through a polysynaptic pathway. During the night, this gland produces and releases the nocturnal hormone melatonin, which circulates throughout the whole body and adjusts several bodily functions according to the existence and duration of darkness. We have previously shown that during the time frame of an inflammatory response, pro-inflammatory cytokines, such as tumor necrosis factor-a, inhibit while anti-inflammatory mediators, such as glucocorticoids, enhance the synthesis of melatonin, interfering in the daily adjustment of the light/dark cycle. Therefore, injury disconnects the organism from environmental cycling, while recovery restores the light/dark information to the whole organism. Here, we extend these observations by evaluating the effect of a mild restraint stress, which did not induce macroscopic gastric lesions. After 2 h of restraint, there was an increase in circulating corticosterone, indicating activation of the hypothalamus-pituitary-adrenal (HPA) axis. In parallel, an increase in melatonin production was observed. Taking into account the data obtained with models of inflammation and stress, we reinforce the hypothesis that the activity of the pineal gland is modulated by the state of the immune system and the HPA axis, implicating the darkness hormone melatonin as a modulator of defense responses.

Mitochondrial DNA Diversity of Orchid Bee Euglossa fimbriata (Hymenoptera: Apidae) Populations Assessed by PCR-RFLP

Euglossa fimbriata is a euglossine species widely distributed in Brazil and occurring primarily in Atlantic Forest remnants. In this study, the genetic mitochondrial structure of E. fimbriata from six Atlantic Forest fragments was studied by RFLP analysis of three PCR-amplified mtDNA gene segments (16S, COI-COII, and cyt b). Ten composite haplotypes were identified, six of which were exclusive and represented singleton mitotypes. Low haplotype diversity (0.085-0.289) and nucleotide diversity (0.000-0.002) were detected within samples. AMOVA partitioned 91.13% of the overall genetic variation within samples and 8.87% (I center dot(st) = 0.089; P < 0.05) among samples. Pairwise comparisons indicated high levels of differentiation among some pairs of samples (I center dot(st) = 0.161-0.218; P < 0.05). These high levels indicate that these populations of E. fimbriata, despite their highly fragmented landscape, apparently have not suffered loss of genetic variation, suggesting that this particular population is not currently endangered.

Isolation and characterization of 15 microsatellite loci in the stingless bee Plebeia remota (Apidae: Meliponini)

The destruction of Brazilian natural habitats has reduced bee populations and negative impacts of native flora pollination have been noticed. This work describes the isolation and characterization of microsatellite loci and evaluates them as molecular markers to study genetic variability of the stingless bee Plebeia remota. A microsatellite enriched genomic library was constructed and 15 primer pairs were designed for this species. The survey was conducted by analyzing 21 unrelated individuals. Genetic diversity indexes were calculated. The mean allelic richness was 6.3, the observed heterozygosity was 0.568, and the percentage of polymorphic loci was 93.33%. Also the primers were tested in cross-species amplification and showed promising results for P. droryana, P. emerina, P. lucii, P. meridionalis, P. pugnax, and P. saiqui. The microsatellite loci described here will be useful to evaluate genetic variability of stingless bees, and certainly will improve our knowledge about population dynamics especially in threatened environments.

Sexually Dimorphic Tegumental Gland Openings in Laniatores (Arachnida, Opiliones), With New Data on 23 Species

Sexually dimorphic glands often release sexual pheromones both in vertebrates and invertebrates. Species of Laniatores (Arachnida, Opiliones) seem to depend on chemical communication but few studies have addressed this topic. In this study, we review the literature for the Phalangida and present new data for 23 species of Laniatores. In 16 taxa, we found previously undescribed sexually dimorphic glandular openings on the femur, patella, metatarsus, and tarsus of legs I and metatarsus of legs III and IV For the other species, we provide scanning electron micrographs of previously undescribed sexually dimorphic setae and pegs located on swollen regions of the legs. We also list additional species in which males have swollen regions on the legs, including the tibia, metatarsus, and tarsus of legs I, trochanter and tibia of legs II, femur, metatarsus, and tarsus of legs III, and metatarsus and tarsus of legs IV. The function and biological role of the secretions released by these glands are discussed. J. Morphol. 271:641-653, 2010. (C) 2009 Wiley-Liss, Inc.

New species of the bee genus Augochlorodes Moure (Hymenoptera, Apidae s. I., Halictinae)

Five new species of the bee genus Augochlorodes from Brazil are described and the type species, A. turrifaciens Moure, 1958, is redescribed. The new species are: A. clementis sp. nov. (from the states of Parana, Santa Catarina and Rio Grande do Sul), A. incomitatus sp. nov. (Rio Grande do Sul), A. politus sp. nov. (Parana), A. rostratus sp. nov. (Rio Grande do Sul) and A. vachali sp. nov. (Parana, Santa Catarina, Sao Paulo). A discriminant function analysis using head measurements is presented to help distinguish the species. An identification key for the species is provided.

TLR4 and CD14 receptors expressed in rat pineal gland trigger NFKB pathway

Nuclear factor-kappa B (NFKB), a pivotal player in inflammatory responses, is constitutively expressed in the pineal gland. Corticosterone inhibits pineal NFKB leading to an enhancement of melatonin production, while tumor necrosis factor (TNF) leads to inhibition of Aa-nat transcription and the production of N-acetylserotonin in cultured glands. The reduction in nocturnal melatonin surge favors the mounting of the inflammatory response. Despite these data, there is no clear evidence of the ability of the pineal gland to recognize molecules that signal infection. This study investigated whether the rat pineal gland expresses receptors for lipopolysaccharide (LPS), the endotoxin from the membranes of Gram-negative bacteria, and to establish the mechanism of action of LPS. Here, we show that pineal glands possess both CD14 and toll-like receptor 4 (TLR4), membrane proteins that bind LPS and trigger the NFKB pathway. LPS induced the nuclear translocation of p50/p50 and p50/RELA dimers and the synthesis of TNF. The maximal expression of TNF in cultured glands coincides with an increase in the expression of TNF receptor 1 (TNFR1) in isolated pinealocytes. In addition, LPS inhibited the synthesis of N-acetylserotonin and melatonin. Therefore, the pineal gland transduces Gram-negative endotoxin stimulation by producing TNF and inhibiting melatonin synthesis. Here, we provide evidence to reinforce the idea of an immune-pineal axis, showing that the pineal gland is a constitutive player in the innate immune response.

Tryptophan hydroxylase is modulated by L-type calcium channels in the rat pineal gland

Calcium is an important second messenger in the rat pineal gland, as well as cAMP. They both contribute to melatonin synthesis mediated by the three main enzymes of the melatonin synthesis pathway: tryptophan hydroxylase, arylalkylamine N-acetyltransferase and hydroxyindole-O-methyltransferase. The cytosolic calcium is elevated in pinealocytes following alpha(1)-adrenergic stimulation, through IP3-and membrane calcium channels activation. Nifedipine, an L-type calcium channel blocker, reduces melatonin synthesis in rat pineal glands in vitro. With the purpose of investigating the mechanisms involved in melatonin synthesis regulation by the L-type calcium channel, we studied the effects of nifedipine on noradrenergic stimulated cultured rat pineal glands. Tryptophan hydroxylase, arylalkylamine N-acetyltransferase and hydroxyindole-O-methyltransferase activities were quantified by radiometric assays and 5-hydroxytryptophan, serotonin, N-acetylserotonin and melatonin contents were quantified by HPLC with electrochemical detection. The data showed that calcium influx blockaded by nifedipine caused a decrease in tryptophan hydroxylase activity, but did not change either arylalkylamine N-acetyltransferase or hydroxyindole-O-methyltransferase activities. Moreover, there was a reduction of 5-hydroxytryptophan, serotonin, N-acetylserotonin and melatonin intracellular content, as well as a reduction of scrotonin and melatonin secretion. Thus, it seems that the calcium influx through L-type high voltage-activated calcium channels is essential for the full activation of tryptophan hydroxylase leading to melatonin synthesis in the pineal gland. (c) 2007 Elsevier Inc. All rights reserved.