DNA methylation is associated with codon degeneracy in a species of bumblebee.

Social insects display extreme phenotypic differences between sexes and castes even though the underlying genome can be almost identical. Epigenetic processes have been proposed as a possible mechanism for mediating these phenotypic differences. Using whole genome bisulfite sequencing of queens, males, and reproductive female workers we have characterised the sex- and caste-specific methylome of the bumblebee Bombus terrestris. We have identified a potential role for DNA methylation in histone modification processes which may influence sex and caste phenotypic differences. We also find differentially methylated genes generally show low levels of DNA methylation which may suggest a separate function for lowly methylated genes in mediating transcriptional plasticity, unlike highly methylated genes which are usually involved in housekeeping functions. We also examined the relationship between the underlying genome and the methylome using whole genome re-sequencing of the same queens and males. We find DNA methylation is enriched at zero-fold degenerate sites. We suggest DNA methylation may be acting as a targeted mutagen at these sites, providing substrate for selection via non-synonymous changes in the underlying genome. However, we did not see any relationship between DNA methylation and rates of positive selection in our samples. In order to fully assess a possible role for DNA methylation in adaptive processes a specifically designed study using natural population data is needed.

Can there be a common, risk-based framework for decisions around live insect trade?

A network of scientists involved in shipment of live insects has met and generated a series of articles on issues related to live insect transport. The network is diverse, covering large-scale commercial interests, government operated areawide control programmes, biomedical research and many smaller applications, in research, education and private uses. Many insect species have a record of safe transport, pose minimal risks and are shipped frequently between countries. The routine shipments of the most frequently used insect model organism for biomedical research, Drosophila melanogaster, is an example. Successful large scale shipments from commercial biocontrol and pollinator suppliers also demonstrate precedents for low-risk shipment categories, delivered in large volumes to high quality standards. Decision makers need access to more information (publications or official papers) that details actual risks from the insects themselves or their possible contaminants, and should propose proportionate levels of management. There may be harm to source environments when insects are collected directly from the wild, and there may be harm to receiving environments. Several risk frameworks include insects and various international coordinating bodies, with experience of guidance on relevant risks, exist. All stakeholders would benefit from an integrated overview of guidance for insect shipping, with reference to types of risk and categories of magnitude, without trying for a single approach requiring universal agreement. Proposals for managing uncertainty and lack of data for smaller or infrequent shipments, for example, must not disrupt trade in large volumes of live insects, which are already supporting strategic objectives in several sectors.

À l'occasion d'une réunion d'experts, un réseau de chercheurs travaillant sur l'expédition d'insectes vivants a produit un ensemble d'articles traitant des questions liées au transport des insectes vivants. Ce réseau est diversifié et représente un large éventail d'intérêts privés et de programmes de lutte biologique à grande échelle menés par les pouvoirs publics, en plus du secteur de la recherche biomédicale et de nombreux acteurs intervenant dans des applications de plus petite envergure relevant de la recherche, de l'enseignement ou du secteur privé. Un grand nombre d'espèces d'insectes sont transportées en toute sécurité avec un niveau de risque minimal, y compris lors des fréquentes expéditions internationales. Un exemple de ces expéditions régulières concerne l'espèce la plus utilisée par la recherche biomédicale en tant qu'organisme modèle, à savoir Drosophila melanogaster. Les exemples réussis d'expéditions à grande échelle provenant de fournisseurs d'agents de lutte biologique et de pollinisateurs produits par le secteur privé offrent également un relevé documenté des diverses catégories d'expéditions à faible risque pour des livraisons d'insectes vivants en grandes quantités et répondant à des normes de qualité élevées. Les décideurs politiques devraient pouvoir accéder à plus d'informations (à travers des publications ou des articles officiels) décrivant en détail les risques réels associés aux insectes eux-mêmes ou à leurs contaminants éventuels, et proposer en connaissance de cause des niveaux de gestion proportionnels à ces risques. La récolte d'insectes prélevés directement de la nature peut être dommageable aussi bien pour les environnements source que pour ceux de destination. Plusieurs cadres fondés sur le risque intègrent désormais les insectes dans leurs directives. Par ailleurs, nombre d'organismes internationaux de coordination ont acquis une expérience dans l'élaboration de lignes directrices face à ces risques. Il serait bénéfique pour toutes les parties prenantes de disposer d'une vue d'ensemble intégrée des directives applicables aux expéditions d'insectes, qui recense les différents types de risque et leurs ordres de grandeur sans se prononcer sur une approche unique qui nécessiterait une adhésion universelle. Ni les propositions visant à gérer l'incertitude ni l'insuffisance des données disponibles sur les expéditions d'insectes en petits nombres ou occasionnelles ne doivent perturber les échanges commerciaux d'insectes vivants en grandes quantités, échanges qui participent aujourd'hui aux objectifs stratégiques de nombreux secteurs.

Una red de científicos relacionados de un modo u otro con el transporte de insectos vivos mantuvo un encuentro y generó una serie de artículos en torno a la cuestión. En la red, muy heterogénea, convergen desde intereses comerciales de gran calado hasta programas públicos de lucha biológica en grandes territorios, pasando por la investigación biomédica y por numerosas aplicaciones de menor dimensión en ámbitos como la investigación, la enseñanza u otros usos privados. Muchas especies de insectos cuentan con un buen historial de seguridad en el transporte, presentan un riesgo mínimo y son expedidas a menudo de un país a otro. Buen ejemplo de ello son los envíos sistemáticos de ejemplares de Drosophila melanogaster, que es el insecto utilizado con más frecuencia como organismo modelo en la investigación biomédica. Otro precedente de envíos voluminosos cuyo transporte y entrega se ajusta a los más exigentes criterios de calidad lo sientan las remesas de grandes cantidades de polinizadores y agentes de control biológico remitidos por proveedores comerciales. Los responsables de adoptar decisiones deben disponer de más y más detallada información (publicaciones o documentos oficiales) sobre los riesgos reales derivados de los propios insectos o sus posibles contaminantes para proponer a partir de ahí medidas de gestión proporcionadas. Los perjuicios ambientales pueden darse tanto en origen (cuando hay captura salvaje de insectos, o sea recolección directa en el medio) como en destino. Hay varios sistemas de determinación del riesgo que incluyen a los insectos y también existen diversos organismos de coordinación internacional que ya tienen experiencia en sentar pautas sobre los riesgos en la materia. Todos los interlocutores del sector se beneficiarían de una visión global e integrada del transporte de insectos, que remita a diferentes tipos de riesgo y categorías de magnitud, sin necesidad de buscar un sistema único que exija consenso universal. Las propuestas para gestionar la incertidumbre y la falta de información en el caso de envíos infrecuentes o de pequeñas dimensiones, por ejemplo, no deben interferir en el transporte de grandes cantidades de insectos vivos, que ya está sirviendo a objetivos estratégicos en varios sectores.

Shipping augmentative biocontrol agents.

The majority of worldwide trading in live arthropods is done by specialised companies that produce and distribute beneficial insects, mites and nematodes for augmentative biological control of pests on crops. These beneficial arthropods, predators or parasitoids of crop pests and some nuisance species, which are harmless to humans, plants and other animals, are mass-reared, transported and released in the target environment as a viable alternative to chemical pesticides. As such, they play a major role in achieving a more sustainable and regenerative agriculture. Thousands of international air shipments are performed yearly by up to 30 major companies. Over the decades that this industry has been active, no significant transport problems have arisen. This is due to stringent standards that the industry has generated, including designated departments to deal with quality control and logistics, as well as guides for each species concerning packaging, storage and transport conditions. In addition, transporters always adhere to the regulatory standards of the importing and exporting countries, which is attested to by the documents included by the companies with each shipment. Two major issues arise when shipping live arthropods: first, the need to maintain stable environmental conditions within the shipping units (maintaining a cool chain) and, second, minimising transport time (preventing delays). This paper discusses the procedures implemented by the companies to assure quality, the documents required and provided currently, and the challenges to the safe transportation of beneficial organisms.

L'essentiel du commerce mondial d'arthropodes vivants est réalisé par des entreprises spécialisées qui produisent et distribuent des insectes, des acariens et des nématodes utiles à des fins de lutte biologique augmentative contre les ravageurs des cultures. Ces arthropodes utiles agissent en tant que prédateurs ou parasitoïdes des espèces de ravageurs ou de nuisibles s'attaquant aux cultures, tout en étant inoffensifs pour l'homme, les végétaux et les autres animaux ; ils font l'objet d'un élevage de masse et sont transportés et relâchés dans l'environnement cible où ils constituent une alternative viable aux pesticides chimiques. À ce titre, ils jouent un rôle majeur en appui d'une agriculture plus durable et régénératrice. Près de 30 grandes entreprises effectuent chaque année des milliers d'expéditions internationales par avion. Aucun incident significatif lié au transport n'a été constaté au cours des décennies d'existence de ce secteur d'activités. Cela est dü aux normes strictes mises en oeuvre par le secteur, en particulier la mise en place de services chargés du contrôle de la qualité et de la logistique ainsi que l'élaboration de guides décrivant, pour chaque espèce, les exigences en matière de conditionnement, de stockage et de transport. En outre, les transporteurs se conforment toujours aux normes réglementaires des pays importateurs et exportateurs, comme l'attestent les documents d'accompagnement fournis par les entreprises lors de chaque expédition. Le transport d'arthropodes vivants présente deux difficultés majeures : d'une part, la nécessité de garantir la stabilité des conditions environnementales au sein des unités d'expédition (respect de la chaîne du froid) et, d'autre part, l'impératif de minimiser le temps de transport (prévention des retards). Les auteurs examinent les procédures mises en oeuvre par les entreprises en termes d'assurance qualité, les documents actuellement requis et fournis ainsi que les défis posés à la sécurité des transports d'organismes utiles.

El grueso del comercio mundial de artrópodos vivos está a cargo de empresas especializadas que producen y distribuyen insectos, ácaros y nemátodos beneficiosos que se destinan al control biológico aumentativo de plagas de los cultivos. Estos artrópodos beneficiosos, predadores o parasitoides de las plagas de los cultivos y otras especies dañinas, son a la vez inocuos para humanos, plantas y otros animales. Tras ser criados a gran escala y transportados, son liberados en el medio destinatario como alternativa viable a los plaguicidas químicos. Cumplen, en este sentido, una función capital para posibilitar una agricultura más sostenible y regeneradora. Cada año, hasta 30 grandes empresas efectúan miles de envíos internacionales por vía aérea. En los varios decenios que este sector lleva activo, nunca ha surgido ningún problema importante de transporte, gracias a las rigurosas normas implantadas por el sector, que incluyen departamentos dedicados específicamente a las cuestiones de logística y control de calidad y guías sobre las condiciones de embalaje, almacenamiento y transporte de cada especie. Además, los transportistas siempre se atienen a la normativa de los países importadores y exportadores, como atestigua la documentación con que las empresas acompañan cada envío. Al transportar remesas de artrópodos vivos hay dos grandes imperativos que plantean sendas dificultades: en primer lugar, el de mantener estables las condiciones del medio en las unidades de transporte (mantenimiento de la cadena del frío); y en segundo lugar, el de reducir al mínimo el tiempo de transporte (evitar demoras). Los autores examinan los procedimientos de garantía de calidad implantados por las empresas, los documentos requeridos y presentados actualmente y las dificultades que plantea el transporte seguro de organismos beneficiosos.

Habitat-specific variation in gut microbial communities and pathogen prevalence in bumblebee queens (Bombus terrestris).

Gut microbial communities are critical for the health of many insect species. However, little is known about how gut microbial communities respond to anthropogenic changes and how such changes affect host-pathogen interactions. In this study, we used deep sequencing to investigate and compare the composition of gut microbial communities within the midgut and ileum (both bacteria and fungi) in Bombus terrestris queens collected from natural (forest) and urbanized habitats. Additionally, we investigated whether the variation in gut microbial communities under each habitat affected the prevalence of two important bumblebee pathogens that have recently been associated with Bombus declines (Crithidia bombi and Nosema bombi). Microbial community composition differed strongly among habitat types, both for fungi and bacteria. Fungi were almost exclusively associated with bumblebee queens from the forest habitats, and were not commonly detected in bumblebee queens from the urban sites. Further, gut bacterial communities of urban B. terrestris specimens were strongly dominated by bee-specific core bacteria like Snodgrassella (Betaproteobacteria) and Gilliamella (Gammaproteobacteria), whereas specimens from the forest sites contained a huge fraction of environmental bacteria. Pathogen infection was very low in urban populations and infection by Nosema was only observed in specimens collected from forest habitats. No significant relationship was found between pathogen prevalence and microbial gut diversity. However, there was a significant and negative relationship between prevalence of Nosema and relative abundance of the core resident Snodgrassella, supporting its role in pathogen defense. Overall, our results indicate that land-use change may lead to different microbial gut communities in bumblebees, which may have implications for bumblebee health, survival and overall fitness.

Impact of factitious foods and prey on the oviposition of the predatory mites Gaeolaelaps aculeifer and Stratiolaelaps scimitus (Acari: Laelapidae).

The soil-dwelling predatory mites Gaeolaelaps aculeifer and Stratiolaelaps scimitus (Mesostigmata: Laelapidae) are important biocontrol agents of several pests (Astigmata, Thysanoptera, Diptera). There is little information regarding the use of factitious foods that potentially improve their mass rearing and population development once released in the field. Here we tested the suitability of several types of factitious food and prey for G. aculeifer and S. scimitus. Factitious foods included eggs of Ephestia kuehniella (Lepidoptera: Pyralidae), hydrated encapsulated cysts of the brine shrimp Artemia sp. (Anostraca: Artemiidae), two species of saprophytic nematodes (Panagrellus redivivus and Panagrellus sp.) (Nematoda: Panagrolaimidae) and pollen of cattail Typha angustifolia (Poales: Typhaceae). Parameters tested were oviposition over a 3-day period compared with controls provided with either second instars of the thrips Frankliniella occidentalis (Thysanoptera: Thripidae) or a mix of instars of the commercially used prey mite Tyrophagus putrescentiae (Astigmatina: Acaridae) or the absence of food. Compared to the standard prey mite T. putrescentiae, G. aculeifer showed elevated oviposition when fed thrips larvae, E. kuehniella eggs, Artemia sp. cysts or the saprophytic P. redivivus. Oviposition by S. scimitus was high when provided with thrips larvae and P. redivivus, but not significantly different from oviposition on T. putrescentiae. Oviposition for both predatory mite species was very low or zero when provided with T. angustifolia pollen. Finally, G. aculeifer consumed significantly more thrips larvae than S. scimitus. The implication of these results for the mass-rearing of G. aculeifer and S. scimitus are discussed.

Hygienic food to reduce pathogen risk to bumblebees.

Bumblebees are ecologically and economically important pollinators, and the value of bumblebees for crop pollination has led to the commercial production and exportation/importation of colonies on a global scale. Commercially produced bumblebee colonies can carry with them infectious parasites, which can both reduce the health of the colonies and spillover to wild bees, with potentially serious consequences. The presence of parasites in commercially produced bumblebee colonies is in part because colonies are reared on pollen collected from honey bees, which often contains a diversity of microbial parasites. In response to this threat, part of the industry has started to irradiate pollen used for bumblebee rearing. However, to date there is limited data published on the efficacy of this treatment. Here we examine the effect of gamma irradiation and an experimental ozone treatment on the presence and viability of parasites in honey bee pollen. While untreated pollen contained numerous viable parasites, we find that gamma irradiation reduced the viability of parasites in pollen, but did not eliminate parasites entirely. Ozone treatment appeared to be less effective than gamma irradiation, while an artificial pollen substitute was, as expected, entirely free of parasites. The results suggest that the irradiation of pollen before using it to rear bumblebee colonies is a sensible method which will help reduce the incidence of parasite infections in commercially produced bumblebee colonies, but that further optimisation, or the use of a nutritionally equivalent artificial pollen substitute, may be needed to fully eliminate this route of disease entry into factories.

An acquired distaste: sugar discrimination by the larval parasitoid Microplitis croceipes (Hymenoptera: Braconidae) is affected by prior sugar exposure.

We examined gustatory responses of the larval parasitoid Microplitis croceipes to determine whether the adults discriminate among common sugars, including fructose, glucose, maltose and sucrose, found in plants. When given single sugar solutions of sucrose, glucose, fructose and maltose at concentrations of 0.008-2.0 mol l(-1), the estimated concentrations at which 50% of wasps initiated feeding ranged between 0.054 and 0.085 mol l(-1) for sucrose, glucose and fructose, which was significantly lower than for maltose. Wasps showed a strong decrease in feeding time for maltose or fructose following a brief exposure to other sugars, suggesting that wasps can distinguish maltose and fructose from the other sugars tested. The higher acceptance threshold and short feeding time in the case of maltose appears adaptive in light of the relatively poor nutritional quality of the sugar in the longevity trial. The pronounced feeding inhibition seen for fructose following exposure to other sugars is not linked with lower nutritional performance. This feeding inhibition was even seen in wasps that had fed on glucose at the lowest acceptance threshold (0.031 mol l(-1)) and persisted for 24 h. This study is the first to show feeding inhibition of otherwise phagostimulant sugars such as maltose and fructose after gustatory stimulation on other sugars.

Plant-herbivore-carnivore interactions in cotton, Gossypium hirsutum: linking belowground and aboveground.

Most studies on plant-herbivore interactions focus on either root or shoot herbivory in isolation, but above- and belowground herbivores may interact on a shared host plant. Cotton (Gossypium spp.) produces gossypol and a variety of other gossypol-like terpenoids that exhibit toxicity to a wide range of herbivores and pathogens. Cotton plants also can emit herbivore-induced volatile compounds at the site of damage and systemically on all tissues above the site of damage. As these volatile compounds attract natural enemy species of the herbivore, they are thought to represent an indirect plant defense. Our study quantified gossypol and gossypol-like compounds in cotton plants with foliage feeding (Heliocoverpa zea), root feeding (Meloidogyne incognita), or their combination. Cotton plants with these treatments were studied also with respect to induced local and systemic volatile production and the attraction of the parasitic wasp Microplitis croceipes to those plants. We also evaluated whether foliage or root feeding affected foliar nitrogen levels in cotton. After 48 hr of leaf feeding and 5 wk of root feeding, local and systemic induction of volatiles (known to attract parasitoids such as M. croceipes) occurred with herbivore damage to leaves, and it increased in levels when root herbivory was added. Nevertheless, M. croceipes were equally attracted to plants with both leaf and root damage and leaf damage only. In contrast to previous studies in cotton, production of gossypol and gossypol-like compounds was not induced in leaf and root tissue following foliage or root herbivory, or their combination. We conclude that root feeding by M. incognita has little influence on direct and indirect defenses of Gossypium hirsutum against insect herbivory.

How host larval age, and nutrition and density of the parasitoid Dinarmus basalis (Hymenoptera: Pteromalidae) influence control of Acanthoscelides obtectus (Coleoptera: Bruchidae).

Choice of the targeted host developmental stage, regulation of parasitoid numbers released and introduction of food supplements are operational factors with a potential to influence the level of biological control. In a closed laboratory storage system maintained over two generations of the host, the impact of these three parameters on the control potential of the parasitoid Dinarmus basalis Rondani was investigated for high populations of larvae of Acanthoscelides obtectus (Say) feeding inside dry common bean seeds Phaseolus vulgaris. The beans were already infested with immature bruchids at the beginning of the storage period to simulate harvest conditions, characterized in a previous study. Treatments resulted in a reduction of 48-75% of the bruchid population within 16 weeks of storage. The best timing of parasitoid release was at the simulated harvest, as later releases reduced the bruchid population only by about half this percentage. Host feeding is postulated to be the key factor involved in the observed difference. The effect of increasing the number of parasitoids strongly depended on host age and food supplement. Addition of vials with honey had no direct effect on the bruchid population or on the parasitoid progeny. The ecological significance of these findings and implications for biological control are discussed.

Above- and below-ground terpenoid aldehyde induction in cotton, Gossypium herbaceum, following root and leaf injury.

Studies on induced defenses have predominantly focused on foliar induction by above-ground herbivores and pathogens. However, roots are attacked by as many if not more phytophages than shoots, so in reality plants are exposed to above- and below-ground attack. Here, we report effects of foliar and/or root damage on terpenoid aldehyde accumulation in cotton (Gossypium herbaceum). Using HPLC, we analyzed concentrations of individual terpenoid aldehydes in foliage and root tissue. In undamaged plants, terpenoid aldehydes were concentrated in young immature main leaves. Concentrations in side leaves, branching from the main leaves, did not differ among leaf position. Above-ground feeding by Spodopterta exigua larvae on a mature leaf enhanced terpenoid concentrations in immature leaves but not in the damaged leaf. In particular, concentrations of hemigossypolone and the heliocides 1 and 4 were enhanced following herbivory. Root herbivory by wireworms (Agriotes lineatus) also resulted in an increase in terpenoid levels in the foliage. In contrast with foliar herbivory, both immature and mature leaves were induced. However, the level of induction after root herbivory was much lower compared to foliar herbivory. Plants exposed to root herbivory also had significantly higher levels of terpenoid aldehydes in root tissue, while no such effect was found following foliar herbivory. Plants exposed to both root and foliar herbivory appeared to induce primarily above-ground at the cost of below-ground defense. The implications for above- and below-ground Mutitrophic interactions are discussed.

The relationship between relative growth rate and susceptibility to aphids in wild barley under different nutrient levels.

The Resource Availability Hypothesis (RAH) states that plants with a low Relative Growth Rate (RGR) and high levels of defence against herbivores or pathogens are favoured in habitats with low resource availability, whereas plants with a high potential RGR and low levels of defence are favoured in environments with high resource availability. High levels of defence are expected to result in lower reproduction and/or growth of the herbivores or pathogens. To test this hypothesis, four accessions of each of nine natural Hordeum spontaneum (wild barley) populations were grown in a climate chamber under two levels of nutrient supply. Susceptibility to Schizaphis graminum (greenbug) was quantified by placing a single adult greenbug on each plant and measuring its realised fecundity after 8 days. Data on potential RGR were available from a previous experiment. No support for the RAH was found. The correlation between potential RGR and greenbug reproduction was not significant, neither at the high nor at the low level of nutrient supply. Furthermore, on average plants grown under high and low nutrients did not differ in susceptibility. However, accessions-within-populations differed in the way susceptibility was affected by nutrient supply, and most accessions had a higher susceptibility under nutrient-poor conditions. It could be that these accessions differed in the spectrum of secondary metabolites they produced. Whatever the cause, the genetic variation for the reaction in susceptibility to nutrient supply suggests that selection could act in favour of more or less plasticity in plants without any apparent change in potential RGR.

Parasitic wasps learn and report diverse chemicals with unique conditionable behaviors.

Parasitoids exploit numerous chemical cues to locate hosts and food. Whether they detect and learn chemicals foreign to their natural history has not been explored. We show that the parasitoid Microplitis croceipes can associate, with food or hosts, widely different chemicals outside their natural foraging encounters. When learned chemicals are subsequently detected, this parasitoid manifests distinct behaviors characteristic with expectations of food or host, commensurate with prior training. This flexibility of parasitoids to rapidly link diverse chemicals to resource needs and subsequently report them with recognizable behaviors offers new insights into their foraging adaptability, and provides a model for further dissection of olfactory learning related processes.

Left ventricular inotropic reserve and right ventricular function predict increase of left ventricular ejection fraction after beta-blocker therapy in nonischemic cardiomyopathy.

OBJECTIVES: The purpose of this study was to determine whether higher left ventricular inotropic reserve, defined as the increase in left ventricular ejection fraction (LVEF) in response to intravenous dobutamine infusion, or other ventriculographic variables predict the increase in LVEF after beta-blocker therapy in patients with nonischemic cardiomyopathy (NICM). BACKGROUND: Long-term beta-blocker therapy increases LVEF in some patients with NICM. Other than dose, there are no definite predictors of LVEF increase. METHODS: Thirty patients with LVEF < or = 0.35 and NICM underwent assessment of LVEF at rest and after a 10-min intravenous infusion of dobutamine at 10 microg/kg/min, using equilibrium radionuclide ventriculography. Age was 49 +/- 11 years, 33% women, functional class 2.6 +/- 0.5, duration of chronic heart failure 3.2 +/- 2.9 years, LVEF 0.21 +/- 0.07, left ventricular end-diastolic volume index 180 +/- 64 ml/m2. Right ventricular ejection fraction (RVEF) was abnormal in 37%. Mean dobutamine-induced augmentation of LVEF (DoALVEF) was 0.12 +/- 0.08. Patients were started on one of three beta-blockers (carvedilol, bucindolol or metoprolol) and the dose was advanced to the maximum tolerated. RESULTS: Left ventricular ejection fraction, reassessed 7.4 +/- 5.9 months after maximum beta-blocker dose was reached, increased to 0.34 +/- 0.13 (p = 0.0006). The following baseline variables correlated with improvement of LVEF: DoALVEF (p = 0.001), RVEF (p = 0.005), systolic blood pressure at end of dobutamine infusion (p = 0.02) and dose of beta-blocker (p = 0.07). In a multivariate analysis, only DoALVEF (p = 0.0003) and RVEF (p = 0.002) were predictive of the increase in LVEF. CONCLUSIONS: Patients with nonischemic cardiomyopathy who have higher left ventricular inotropic reserve and normal RVEF derive higher increase in LVEF from beta-blocker therapy.

Cardiac responses to insulin-induced hypoglycemia in nondiabetic and intensively treated type 1 diabetic patients.

Insulin-induced hypoglycemia occurs commonly in intensively treated patients with type 1 diabetes, but the cardiovascular consequences of hypoglycemia in these patients are not known. We studied left ventricular systolic [left ventricular ejection fraction (LVEF)] and diastolic [peak filling rate (PFR)] function by equilibrium radionuclide angiography during insulin infusion (12 pmol. kg(-1). min(-1)) under either hypoglycemic (approximately 2.8 mmol/l) or euglycemic (approximately 5 mmol/l) conditions in intensively treated patients with type 1 diabetes and healthy nondiabetic subjects (n = 9 for each). During hypoglycemic hyperinsulinemia, there were significant increases in LVEF (DeltaLVEF = 11 +/- 2%) and PFR [DeltaPFR = 0.88 +/- 0.18 end diastolic volume (EDV)/s] in diabetic subjects as well as in the nondiabetic group (DeltaLVEF = 13 +/- 2%; DeltaPFR = 0.79 +/- 0.17 EDV/s). The increases in LVEF and PFR were comparable overall but occurred earlier in the nondiabetic group. A blunted increase in plasma catecholamine, cortisol, and glucagon concentrations occurred in response to hypoglycemia in the diabetic subjects. During euglycemic hyperinsulinemia, LVEF also increased in both the diabetic (DeltaLVEF = 7 +/- 1%) and nondiabetic (DeltaLVEF = 4 +/- 2%) groups, but PFR increased only in the diabetic group. In the comparison of the responses to hypoglycemic and euglycemic hyperinsulinemia, only the nondiabetic group had greater augmentation of LVEF, PFR, and cardiac output in the hypoglycemic study (P < 0.05 for each). Thus intensively treated type 1 diabetic patients demonstrate delayed augmentation of ventricular function during moderate insulin-induced hypoglycemia. Although diabetic subjects have a more pronounced cardiac response to hyperinsulinemia per se than nondiabetic subjects, their response to hypoglycemia is blunted.

A comparison of nectar- and honeydew sugars with respect to their utilization by the hymenopteran parasitoid Cotesia glomerata.

Fourteen naturally occurring sugars were individually tested with respect to their effect on Cotesia glomerata longevity. Parasitoids kept with solutions of either sucrose, glucose and fructose lived for >30 days. This constitutes a factor 15 increase in life span in comparison to control individuals kept with water only. Stachyose, mannose, melezitose, melibiose, maltose and erlose increased parasitoid longevity by a factor of 11.2-6.9. Solutions of galactose and trehalose had a marginal, but still significant effect. Lactose and raffinose did not raise parasitoid longevity, while rhamnose actually reduced parasitoid survival. In an additional experiment, the relationship between quantity of sugar consumption and longevity was established for all 14 sugars. To study the effect of an unsuitable sugar in sugar mixtures, a range of glucose:rhamnose mixtures was tested. Even at 20% of the sugar mixture rhamnose suppressed the nutritional benefit of the 80% glucose. The nutritional suitability of the sugars shows a positive correlation with the previously reported gustatory response towards the individual sugars. Patterns of sugar utilization are discussed with respect to hydrolytic enzymes and carbohydrate biochemical characteristics. Our findings for C. glomerata are compared to patterns of sugar utilization reported for other species. The comparison between C. glomerata and its host Pieris brassicae reveals that the parasitoid is capable of utilizing a range of sugars that are unsuitable to its herbivorous host. This specificity opens up opportunities to select food supplements for biological control programs that selectively target the antagonist, without concurrently enhancing herbivore fitness.

Selective use of single-photon emission computed tomography myocardial perfusion imaging in a chest pain center.

Emergency department chest pain centers (CPCs) vary in their approach to patients with chest pain and nonischemic electrocardiograms (ECG). Although single-photon emission computed tomography (SPECT) myocardial perfusion imaging has been evaluated in this setting, both acutely at rest and after stress, we questioned its application in all patients. We prospectively evaluated the utility of selective SPECT imaging in a CPC (i.e., rest SPECT for ongoing pain, stress SPECT if unable to undergo exercise electrocardiography) and its impact on the overall disposition of all emergency department chest pain patients. Over 3 years, 2,601 patients were evaluated in a CPC (2,211 [85%] were sent home, 390 [15%] were hospitalized). Of 390 CPC patients hospitalized, 182 (47%) were diagnosed with coronary artery disease at the time of hospital discharge. Only 28 patients (1.1%) had an acute myocardial infarction. After 3 years, the proportion of all chest pain patients hospitalized and those diagnosed as "rule-out myocardial infarction" decreased from 53% to 41% and 32% to 18% of all chest pain patients, respectively (both p <0.0001). Overall, 906 patients (35%) required SPECT imaging to complete the CPC evaluation. Had SPECT imaging not been performed selectively, and all 906 patients been admitted, 762 (29%) would have been hospitalized unnecessarily based on the final diagnoses. Alternatively, sending all these patients home would have resulted in 144 (6%) inappropriate discharges of patients with coronary artery disease. A CPC protocol using the selective use of SPECT imaging permits the complete evaluation of all patients in the CPC, significantly reduces hospitalizations for chest pain, and restricts hospital admission to more appropriate patients.

Dobutamine-induced augmentation of left ventricular ejection fraction predicts survival of heart failure patients with severe non-ischaemic cardiomyopathy.

AIMS: The prognosis of patients with severe non-ischaemic dilated cardiomyopathy is variable. The predictive value of currently utilized tests is suboptimal. The purpose of this study was to determine the prognostic value of dobutamine-induced augmentation of left ventricular ejection fraction in patients with non-ischaemic dilated cardiomyopathy. METHODS AND RESULTS: Sixty-two patients with left ventricular ejection fraction < or =0.30 underwent exercise testing with gas exchange analysis and assessment of left ventricular ejection fraction at rest and after a 10-min intravenous infusion of dobutamine at 10 microg x kg(-1) x min(-1), using equilibrium radionuclide ventriculography. Age was 48+/-11 years, 32% females, functional class 2.6+/-0.6, resting left ventricular ejection fraction 0.20+/-0.06, and peak exercise oxygen consumption (mVO2) 19+/-6 ml x kg(-1) x min(-1). Mean dobutamine-induced augmentation of left ventricular ejection fraction (DeltaLVEF) was 0.09+/-0.06 (median 0.08, range -0.03 to 0.26). Follow-up was 25+/-15 months during which there were 12 deaths and five transplantations. Patients were divided into two groups based on median DeltaLVEF. The transplant-free survival was better in the group with higher DeltaLVEF (94% vs 64%, P<0.008). In multivariate analysis incorporating age, gender, duration of chronic heart failure, functional class, right and left ventricular ejection fraction, DeltaLVEF, left ventricular end-diastolic volume index, and mVO2, only DeltaLVEF was predictive of 1-year, 3-year, and overall transplant-free survival (RR 0.09, 0.03, and 0.13;P 0.03, 0.09, and 0.08 respectively). The linear correlation between DeltaLVEF and mVO2(r=0.3) and between DeltaLVEF and left ventricular ejection fraction (r=0.5) was weak. CONCLUSION: Dobutamine-induced augmentation of left ventricular ejection fraction is a strong prognostic variable, independent of exercise capacity and resting ventriculographic variables, in severe non-ischaemic systolic dysfunctional heart failure.

Interaction of vibrational and visual cues in parasitoid host location.

Female parasitoids are guided by multisensory information during host finding. Individual cues are used in an interactive or a hierarchical manner according to the relative importance on the spatial scale of their effect. Unlike most studies that concentrate on single cues, the present paper investigates the interaction of two physical cues. The interaction of mechanosensory and visual cues was studied in the pupal parasitoid Pimpla turionellae (Hymenoptera: Ichneumonidae). This species uses, amongst other senses, vibrational sounding (echolocation in a solid substrate) to find its mainly endophytic hosts. Location and frequency of ovipositor insertions were scored on cylindrical plant stem models with single or combined cues. Single-cue experiments show that parasitoids use both visual and mechanosensory cues and achieve a similar precision of host location with either cue. The combination of vision and vibrational sounding increased the precision of host location by a factor of approximately two to three. We conclude that the two senses interact, resulting in an additive accuracy. Neither the visual nor the mechanosensory cue was favored when offered adjacent to each other on the same stem model. On the investigated spatial scale, both physical cues are used and seem to be equally important for host location in this species.

Effect of left ventricular volume on results of coronary artery bypass grafting.

After coronary artery bypass grafting, our patients with ischemic cardiomyopathy and significant left ventricular (LV) dilation demonstrated an improvement in angina symptoms, acceptable operative and medium-term survival, a trend toward improvement in LV ejection fraction, and a significant reduction in LV chamber size. Our results suggest that patients with ischemic cardiomyopathy and LV dilation should not be excluded from surgical revascularization based on ventricular size alone.