On the first tachinid fly (Diptera, Tachinidae) carrying Asclepiadoideae pollinaria in the Neotropical Region

On the first tachinid fly (Diptera, Tachinidae) carrying Asclepiadoideae pollinaria in the Neotropical Region. This paper reports the first Neotropical Tachinidae species possibly associated to pollination of Asclepiadoideae: a female of Euacaulona sumichrasti Townsend, 1908 (Diptera, Tachinidae, Phasiinae, Trichopodini) carrying pollinaria of Gonolobus parviflorus Decne., 1844 (Apocynaceae, Asclepiadoideae, Asclepiadeae: Gonolobinae) attached to its proboscis. The fly specimen was collected in Paraguay, Departamento Canindeyú. The pollinarium is illustrated and described herein. This represents the first anthophilous record to G. parviflorus and to the genus.

Differences between the quality of strawberries (Fragaria x ananassa) pollinated by the stingless bees Scaptotrigona aff. depilis and Nannotrigona testaceicornis

We investigated the success of two stingless bee species in pollinating strawberries in greenhouses. Three greenhouses and one open field area were used; one greenhouse had only strawberry plants (control), another (G1) had three colonies of Scaptotrigona aff. depilis and another (G2) had three colonies of Nannotrigona testaceicornis. In the open field area, the flowers could be visited by any bee. The total production of fruits was counted and a random sample (N = 100) from each area was used to measure weight, length, circumference, and achenes number (N = 5). The percentages of deformed strawberries were: 23% (no bees); 2% (greenhouses with bees) and 13% (open field). The strawberries from the greenhouse with N. testaceicornis and the open field were heavier than those from the greenhouses with no bees and with S. depilis. The fruit circumference was largest in the greenhouses with bees. The achenes number did not differ among the experimental areas. The strawberries produced in the greenhouses with stingless bees had more quality and greater commercial value than the fruits produced in the open field area and the greenhouse without bees. We conclude that stingless bees are efficient pollinators of strawberry flowers cultivated in greenhouses.

Food profitability affects intranidal recruitment behaviour in the stingless bee Nannotrigona testaceicornis

Does the food's sugar concentration affect recruitment behaviour in the stingless bee Nan-notrigona testaceicornis? We recorded intranidal forager behaviour while offering sugar water of constant, increasing, or decreasing concentrations. Running speed was not correlated with sugar concentration but the jostling contacts/sec were. Food profitability also affected the recruiter's thorax vibrations: Pulse duration and duty cycle followed both concentration increases and decreases. Sugar concentration also influenced the number of recruited bees. In comparison to the phylogenetically closely related Scaptotrigona, Nan-notrigona's intranidal recruitment behaviour showed a more elaborate association with food profitability. This is likely to reflect differences in ecology and foraging strategies as Nannotrigona - in contrast to Scaptotrigona - does not lay scent trails to guide recruits to a food source.

Transiting exoplanets from the CoRoT space mission XVIII. CoRoT-18b: a massive hot Jupiter on a prograde, nearly aligned orbit

We report the detection of CoRoT-18b, a massive hot Jupiter transiting in front of its host star with a period of 1.9000693 +/- 0.0000028 days. This planet was discovered thanks to photometric data secured with the CoRoT satellite combined with spectroscopic and photometric ground-based follow-up observations. The planet has a mass M(p) = 3.47 +/- 0.38 M(Jup), a radius R(p) = 1.31 +/- 0.18 R(Jup), and a density rho(p) = 2.2 +/- 0.8 g cm(-3). It orbits a G9V star with a mass M(*) = 0.95 +/- 0.15 M(circle dot), a radius R(*) = 1.00 +/- 0.13 R(circle dot), and a rotation period P(rot) = 5.4 +/- 0.4 days. The age of the system remains uncertain, with stellar evolution models pointing either to a few tens Ma or several Ga, while gyrochronology and lithium abundance point towards ages of a few hundred Ma. This mismatch potentially points to a problem in our understanding of the evolution of young stars, with possibly significant implications for stellar physics and the interpretation of inferred sizes of exoplanets around young stars. We detected the RossiterMcLaughlin anomaly in the CoRoT-18 system thanks to the spectroscopic observation of a transit. We measured the obliquity psi = 20 degrees +/- 20 degrees +/- (sky-projected value lambda = -10 degrees +/- 20 degrees), indicating that the planet orbits in the same way as the star is rotating and that this prograde orbit is nearly aligned with the stellar equator.

Transiting exoplanets from the CoRoT space mission XII. CoRoT-12b: a short-period low-density planet transiting a solar analog star

We report the discovery by the CoRoT satellite of a new transiting giant planet in a 2.83 days orbit about a V = 15.5 solar analog star (M(*) = 1.08 +/- 0.08 M(circle dot), R(*) = 1.1 +/- 0.1 R(circle dot), T(eff) = 5675 +/- 80 K). This new planet, CoRoT-12b, has a mass of 0.92 +/- 0.07 M(Jup) and a radius of 1.44 +/- 0.13 R(Jup). Its low density can be explained by standard models for irradiated planets.

The Missing Part of Seed Dispersal Networks: Structure and Robustness of Bat-Fruit Interactions

Mutualistic networks are crucial to the maintenance of ecosystem services. Unfortunately, what we know about seed dispersal networks is based only on bird-fruit interactions. Therefore, we aimed at filling part of this gap by investigating bat-fruit networks. It is known from population studies that: (i) some bat species depend more on fruits than others, and (ii) that some specialized frugivorous bats prefer particular plant genera. We tested whether those preferences affected the structure and robustness of the whole network and the functional roles of species. Nine bat-fruit datasets from the literature were analyzed and all networks showed lower complementary specialization (H(2)' = 0.3760.10, mean 6 SD) and similar nestedness (NODF = 0.5660.12) than pollination networks. All networks were modular (M=0.32 +/- 0.07), and had on average four cohesive subgroups (modules) of tightly connected bats and plants. The composition of those modules followed the genus-genus associations observed at population level (Artibeus-Ficus, Carollia-Piper, and Sturnira-Solanum), although a few of those plant genera were dispersed also by other bats. Bat-fruit networks showed high robustness to simulated cumulative removals of both bats (R = 0.55 +/- 0.10) and plants (R = 0.68 +/- 0.09). Primary frugivores interacted with a larger proportion of the plants available and also occupied more central positions; furthermore, their extinction caused larger changes in network structure. We conclude that bat-fruit networks are highly cohesive and robust mutualistic systems, in which redundancy is high within modules, although modules are complementary to each other. Dietary specialization seems to be an important structuring factor that affects the topology, the guild structure and functional roles in bat-fruit networks.

Successful maintenance of a stingless bee population despite a severe genetic bottleneck

Stingless bees play an important ecological role as pollinators of many wild plant species in the tropics and have significant potential for the pollination of agricultural crops. Nevertheless, conservation efforts as well as commercial breeding programmes require better guidelines on the amount of genetic variation that is needed to maintain viable populations. In this context, we carried out a long-term genetic study on the stingless bee Melipona scutellaris to evaluate the population viability consequences of prolonged breeding from a small number of founder colonies. In particular, it was artificially imposed a genetic bottleneck by setting up a population starting from only two founder colonies, and continued breeding from it for a period of over 10 years in a location outside its natural area of occurrence. We show that despite a great reduction in the number of alleles present at both neutral microsatellite loci and the sex-determining locus relative to its natural source population, and an increased frequency in the production of sterile diploid males, the genetically impoverished population could be successfully bred and maintained for at least 10 years. This shows that in stingless bees, breeding from a small stock of colonies may have less severe consequences than previously suspected. In addition, we provide a simulation model to determine the number of colonies that are needed to maintain a certain number of sex alleles in a population, thereby providing useful guidelines for stingless bee breeding and conservation efforts.

Inhibition of Auxin Transport from the Ovary or from the Apical Shoot Induces Parthenocarpic Fruit-Set in Tomato Mediated by Gibberellins

Fruit-set in tomato (Solanum lycopersicum) depends on gibberellins and auxins (GAs). Here, we show, using the cv MicroTom, that application of N-1-naphthylphthalamic acid (NPA; an inhibitor of auxin transport) to unpollinated ovaries induced parthenocarpic fruit-set, associated with an increase of indole-3-acetic acid (IAA) content, and that this effect was negated by paclobutrazol (an inhibitor of GA biosynthesis). NPA-induced ovaries contained higher content of GA(1) (an active GA) and transcripts of GA biosynthetic genes (SlCPS, SlGA20ox1, and -2). Interestingly, application of NPA to pollinated ovaries prevented their growth, potentially due to supraoptimal IAA accumulation. Plant decapitation and inhibition of auxin transport by NPA from the apical shoot also induced parthenocarpic fruit growth of unpollinated ovaries. Application of IAA to the severed stump negated the plant decapitation effect, indicating that the apical shoot prevents unpollinated ovary growth through IAA transport. Parthenocarpic fruit growth induced by plant decapitation was associated with high levels of GA(1) and was counteracted by paclobutrazol treatment. Plant decapitation also produced changes in transcript levels of genes encoding enzymes of GA biosynthesis (SlCPS and SlGA20ox1) in the ovary, quite similar to those found in NPA-induced fruits. All these results suggest that auxin can have opposing effects on fruit-set, either inducing (when accumulated in the ovary) or repressing (when transported from the apical shoot) that process, and that GAs act as mediators in both cases. The effect of NPA application and decapitation on fruit-set induction was also observed in MicroTom lines bearing introgressed DWARF and SELF-PRUNING wild-type alleles.

Pheromone paths attached to the substrate in meliponine bees: helpful but not obligatory for recruitment success

In contrast to marking of the location of resources or sexual partners using single-spot pheromone sources, pheromone paths attached to the substrate and assisting orientation are rarely found among flying organisms. However, they do exist in meliponine bees (Apidae, Apinae, Meliponini), commonly known as stingless bees, which represent a group of important pollinators in tropical forests. Worker bees of several Neotropical meliponine species, especially in the genus Scaptotrigona Moure 1942, deposit pheromone paths on substrates between highly profitable resources and their nest. In contrast to past results and claims, we find that these pheromone paths are not an indispensable condition for successful recruitment but rather a means to increase the success of recruiters in persuading their nestmates to forage food at a particular location. Our results are relevant to a speciation theory in scent path-laying meliponine bees, such as Scaptotrigona. In addition, the finding that pheromone path-laying bees are able to recruit to food locations even across barriers such as large bodies of water affects tropical pollination ecology and theories on the evolution of resource communication in insect societies with a flying worker caste.

Quantitative Trait Loci Mapping and The Genetic Basis of Heterosis in Maize and Rice

Despite its importance to agriculture, the genetic basis of heterosis is still not well understood. The main competing hypotheses include dominance, overdominance, and epistasis. NC design III is an experimental design that. has been used for estimating the average degree of dominance of quantitative trait 106 (QTL) and also for studying heterosis. In this study, we first develop a multiple-interval mapping (MIM) model for design III that provides a platform to estimate the number, genomic positions, augmented additive and dominance effects, and epistatic interactions of QTL. The model can be used for parents with any generation of selling. We apply the method to two data sets, one for maize and one for rice. Our results show that heterosis in maize is mainly due to dominant gene action, although overdominance of individual QTL could not completely be ruled out due to the mapping resolution and limitations of NC design III. For rice, the estimated QTL dominant effects could not explain the observed heterosis. There is evidence that additive X additive epistatic effects of QTL could be the main cause for the heterosis in rice. The difference in the genetic basis of heterosis seems to be related to open or self pollination of the two species. The MIM model for NC design III is implemented in Windows QTL Cartographer, a freely distributed software.

Pollen and stigma morphology of some Phaseoleae species (Leguminosae) with different pollinators

Pollen transport to a receptive stigma can be facilitated through different pollinators, which submits the pollen to different selection pressures. This study aimed to associate pollen and stigma morphology with zoophily in species of the tribe Phaseoleae. Species of the genera Erythrina, Macroptilium and Mucuna with different pollinators were chosen. Pollen grains and stigmas were examined under light microscopy (anatomy), scanning electronic microscopy (surface analyses) and transmission electronic microscopy (ultrastructure). The three genera differ in terms of pollen wall ornamentation, pollen size, pollen aperture, thickness of the pollen wall, amount of pollenkitt, pollen hydration status and dominant reserves within the pollen grain, while species within each genus are very similar in most studied characteristics. Most of these features lack relationships to pollinator type, especially in Erythrina and Mucuna. Pollen reserves are discussed on a broad scale, according to the occurrence of protein in the pollen of invertebrate- or vertebrate-pollinated species. Some pollen characteristics are more associated to semi-dry stigma requirements. This apical, compact, cuticularised and secretory stigma occurs in all species investigated. We conclude that data on pollen and stigma structure should be included together with those on floral morphology and pollinator behaviour for the establishment of functional pollination classes.

A protein with protective properties against the cellular defense reactions in insects

The molecular mechanism of how insects recognize intruding microorganisms and parasites and distinguish them from own body structures is not well known. We explored evolutionary adaptations in an insect parasitoid host interaction to identify components that interfere with the recognition of foreign objects and cellular encapsulation. Because some parasitoids provide protection for the developing wasp in the absence of an overt suppression of the insect host defense, we analyzed the surface of eggs and symbiotic viruses for protective properties. Here we report on the molecular cloning of a 32-kDa protein (Crp32) that is one of the major protective components. It is produced in the calyx cells of the female wasp ovaries and attached to the surface of the egg and other particles including polydnaviruses. The recombinant protein confers protection to coated objects in a cellular encapsulation assay suggesting that a layer of Crp32 may prevent cellular encapsulation reactions by a local inactivation of the host defense system.

Structure and distribution of N-glycans on the S-7-allele stylar self-incompatibility ribonuclease of Nicotiana alata

S-RNases are the stylar products of the self-incompatibility (S)-locus in solanaceous plants (including Nicotiana alata), and as such, are involved in the prevention of self-pollination. All cDNA sequences of S-RNase products of functional S-alleles contain potential N-glycosylation sites, with one site being conserved in all cases, suggesting that N-glycosylation is important in self-incompatibility. In this study, we report on the structure and localization of the N-glycans on the S-7-allele RNase of N, alata, A total of nine N-glycans, belonging to the high-mannose- and xylosylated hybrid-classes, were identified and characterized by a combination of electrospray-ionization mass-spectrometry (ESI-MS), H-1-NMR spectroscopy, and methylation analyses. The glycosylation pattern of individual glycosylation sites was determined by ESI-MS of the glycans released from isolated chymotryptic glycopeptides, All three N-glycosylation sites showed microheterogeneity and each had a unique complement of N-glycans, The N-glycosylation pattern of the S-7-RNase is significantly different to those of the S-1- and S-2-RNases.

A coiled-coil region of an insect immune suppressor protein is involved in binding and uptake by hemocytes

Polydnaviruses are associated with certain parasitoid wasps and are introduced into the body cavity of the host caterpillar during oviposition. Some of the viral genes are expressed in host tissues and corresponding proteins are secreted into the hemocoel causing suppression of the host immune system. The Cotesia rubecula polydnavirus gene product, CrV1, effectively inactivates hemocytes by mediating cytoskeleton break-down. A precondition for the CrV1 function is the incorporation of the extracellular protein by hemocytes. Here, we show that a coiled-coil domain containing a putative leucine zipper is required for CrV1 function, since removal of this domain abolishes binding and uptake of the CrV1 protein by hemocytes. (C) 2002 Elsevier Science Ltd. All rights reserved.

Isolation and characterization of a neprilysin-like protein from Venturia canescens virus-like particles

Maternal protein secretions from endoparasitoid wasps are evolutionary adaptations to regulate host physiology as part of an extended wasp phenotype. Virus-like particles (VLPs) produced in the calyx region of Venturia canescens wasps are involved in immune evasion of the developing parasitoid inside the host. In contrast to polydnaviruses (PDVs), VcVLPs are devoid of any nucleic acids. To understand the role of these particles in the regulation of host physiology and phylogenetic relationship between VLPs and PDVs, it is essential to identify particle proteins. In this paper, we describe the isolation and molecular cloning of a neprilysin-like gene (VcNEP) coding for a 94 kDa VcVLP protein and discuss its possible role in host regulation.