Quantifying forage specialisation in polyphagic insects: the polylectic and rare solitary bee, Colletes floralis (Hymenoptera: Colletidae)

Many insect species vary in their degree of foraging specialisation, with many bee species considered polyphagic (polylectic). Wild, non-managed bee species vary in their conservation status, and species-specific biological traits such as foraging specialisation may play an important role in determining variance in population declines. Current agri-environment schemes (AESs) prescribe the introduction of flower seed mixes for agricultural systems to aid the conservation of wild bees. However, the extent to which flower combinations adequately meet bee foraging requirements is poorly known. We quantitatively assessed pollen use and selectivity using two statistical approaches: Bailey's Intervals and Compositional Analysis, in an examplar species, a purportedly polylectic and rare bee, Colletes floralis, across 7 sites through detailed analysis of bee scopal pollen loads and flower abundance. Both approaches provided good congruence, but Compositional Analysis was more robust to small sample sizes. We advocate its use for the quantitative determination of foraging behaviour and dietary preference. Although C. floralis is polylectic, it showed a clear dietary preference for plants within the family Apiaceae. Where Apiaceae was uncommon, the species exploited alternative resources. Other plant families, such as the Apiaceae, could be included, or have their proportion increased in AES seed mixes, to aid the management of C. floralis and potentially other wild solitary bees of conservation concern. © 2011 The Authors. Insect Conservation and Diversity © 2011 The Royal Entomological Society.

A tale of two chitons: Is habitat specialisation linked to distinct associated bacterial communities?

Although most chitons (Mollusca: Polyplacophora) are shallow-water molluscs, diverse species also occur in deep-sea habitats. We investigated the feeding strategies of two species, Leptochiton boucheti and Nierstraszella lineata, recovered on sunken wood sampled in the western Pacific, close to the Vanuatu Islands. The two species display distinctly different associations with bacterial partners. Leptochiton boucheti harbours Mollicutes in regions of its gut epithelium and has no abundant bacterium associated with its gill. Nierstraszella lineata displays no dense gut-associated bacteria, but harbours bacterial filaments attached to its gill epithelium, related to the Deltaproteobacteria symbionts found in gills of the wood-eating limpet Pectinodonta sp. Stable carbon and nitrogen isotope signatures and an absence of cellulolytic activity give evidence against a direct wood-feeding diet; both species are secondary consumers within the wood food web. We suggest that the distinct associations with bacterial partners are linked to niche specialisations of the two species. Nierstraszella lineata is in a taxonomic family restricted to sunken wood and is possibly adapted to more anoxic conditions thanks to its gill-associated bacteria. Leptochiton boucheti is phylogenetically more proximate to an ancestral form not specialised on wood and may itself be more of a generalist; this observation is congruent with its association with Mollicutes, a bacterial clade comprising gut-associated bacteria occurring in several metazoan phyla.

Relative Efficiencies of the Burkard 7-Day, Rotorod and Burkard Personal Samplers for Poaceae and Urticaceae Pollen under Field Conditions

Introduction: In aerobiological studies it is often necessary to compare concentration data recorded with different models of sampling instrument. Sampler efficiency typically varies from device to device, and depends on the target aerosol and local atmospheric conditions. To account for these differences inter-sampler correction factors may be applied, however for many pollen samplers and pollen taxa such correction factors do not exist and cannot be derived from existing published work. Materials and methods: In this study the relative efficiencies of the Burkard 7-Day Recording Volumetric Spore Trap, the Sampling Technologies Rotorod Model 20 and the Burkard Personal Volumetric Air Sampler were evaluated for Urticaceae and Poaceae pollen under field conditions, and the influence of wind speed and relative humidity on these efficiency relationships was assessed. Data for the two pollen taxa were collected during 2010 and 2011-12 respectively. Results: The three devices were found to record significantly different concentrations for both pollen taxa, with the exception of the 7-Day and Rotorod samplers for Poaceae pollen. Under the range of conditions present during the study wind speed was found to only have a significant impact on inter-sampler relationships involving the vertically orientated Burkard Personal sampler, whilst no interaction between relative efficiency and relative humidity was observed. Conclusions: Data collected with the three models of sampler should only be compared once the appropriate correction has been made, with wind speed taken into account where appropriate.

Horizontal nutrient fluxes and production efficiencies in urban and peri-urban crop and livestock husbandry of Niamey, Niger

Urban and peri-urban agriculture (UPA) increasingly supplies food and non-food values to the rapidly growing West African cities. However, little is known about the resource use efficiencies in West African small-scale UPA crop and livestock production systems, and about the benefits that urban producers and retailers obtain from the cultivation and sale of UPA products. To contribute to filling this gap of knowledge, the studies comprising this doctoral thesis determined nutrient use efficiencies in representative urban crop and livestock production system in Niamey, Niger, and investigated potential health risks for consumers. Also assessed was the economic efficiency of urban farming activities. The field study, which was conducted during November 2005 to January 2008, quantified management-related horizontal nutrient flows in 10 vegetable gardens, 9 millet fields and 13 cattle and small ruminant production units. These farms, selected on the basis of a preceding study, represented the diversity of UPA crop and livestock production systems in Niamey. Based on the management intensity, the market orientation and especially the nutrient input to individual gardens and fields, these were categorized as high or low input systems. In the livestock study, high and low input cattle and small ruminant units were differentiated based on the amounts of total feed dry matter offered daily to the animals at the homestead. Additionally, economic returns to gardeners and market retailers cultivating and selling amaranth, lettuce, cabbage and tomato - four highly appreciated vegetables in Niamey were determined during a 6-months survey in forty gardens and five markets. For vegetable gardens and millet fields, significant differences in partial horizontal nutrient balances were determined for both management intensities. Per hectare, average annual partial balances for carbon (C), nitrogen (N), phosphorus (P) and potassium (K) amounted to 9936 kg C, 1133 kg N, 223 kg P and 312 kg K in high input vegetable gardens as opposed to 9580 kg C, 290 kg N, 125 kg P and 351 kg K in low input gardens. These surpluses were mainly explained by heavy use of mineral fertilizers and animal manure to which irrigation with nutrient rich wastewater added. In high input millet fields, annual surpluses of 259 kg C ha-1, 126 kg N ha-1, 20 kg P ha-1 and 0.4 kg K ha-1 were determined. Surpluses of 12 kg C ha-1, 17 kg N ha-1, and deficits of -3 kg P ha-1 and -3 kg K ha-1 were determined for low input millet fields. Here, carbon and nutrient inputs predominantly originated from livestock manure application through corralling of sheep, goats and cattle. In the livestock enterprises, N, P and K supplied by forages offered at the farm exceeded the animals’ requirements for maintenance and growth in high and low input sheep/goat as well as cattle units. The highest average growth rate determined in high input sheep/goat units was 104 g d-1 during the cool dry season, while a maximum average gain of 70 g d-1 was determined for low input sheep/goat units during the hot dry season. In low as well as in high input cattle units, animals lost weight during the hot dry season, and gained weight during the cool dry season. In all livestock units, conversion efficiencies for feeds offered at the homestead were rather poor, ranging from 13 to 42 kg dry matter (DM) per kg live weight gain (LWG) in cattle and from 16 to 43 kg DM kg-1 LWG in sheep/goats, pointing to a substantial waste of feeds and nutrients. The economic assessment of the production of four high value vegetables pointed to a low efficiency of N and P use in amaranth and lettuce production, causing low economic returns for these crops compared to tomato and cabbage to which inexpensive animal manure was applied. The net profit of market retailers depended on the type of vegetable marketed. In addition it depended on marketplace for amaranth and lettuce, and on season and marketplace for cabbage and tomato. Analysis of faecal pathogens in lettuce irrigated with river water and fertilized with animal manure indicated a substantial contamination by Salmonella spp. with 7.2 x 104 colony forming units (CFU) per 25 g of produce fresh matter, while counts of Escherichia coli averaged 3.9 x 104 CFU g-1. In lettuce irrigated with wastewater, Salmonella counts averaged 9.8 x 104 CFU 25 g-1 and E. coli counts were 0.6 x 104 CFU g-1; these values exceeded the tolerable contamination levels in vegetables of 10 CFU g-1 for E. coli and of 0 CFU 25 g-1 for Salmonella. Taken together, the results of this study indicate that Niamey’s UPA enterprises put environmental safety at risk since excess inputs of N, P and K to crop and livestock production units favour N volatilisation and groundwater pollution by nutrient leaching. However, more detailed studies are needed to corroborate these indications. Farmers’ revenues could be significantly increased if nutrient use efficiency in the different production (sub)systems was improved by better matching nutrient supply through fertilizers and feeds with the actual nutrient demands of plants and animals.

Bayesian ranking and selection of fishing boat efficiencies

The steadily accumulating literature on technical efficiency in fisheries attests to the importance of efficiency as an indicator of fleet condition and as an object of management concern. In this paper, we extend previous work by presenting a Bayesian hierarchical approach that yields both efficiency estimates and, as a byproduct of the estimation algorithm, probabilistic rankings of the relative technical efficiencies of fishing boats. The estimation algorithm is based on recent advances in Markov Chain Monte Carlo (MCMC) methods—Gibbs sampling, in particular—which have not been widely used in fisheries economics. We apply the method to a sample of 10,865 boat trips in the US Pacific hake (or whiting) fishery during 1987–2003. We uncover systematic differences between efficiency rankings based on sample mean efficiency estimates and those that exploit the full posterior distributions of boat efficiencies to estimate the probability that a given boat has the highest true mean efficiency.

Heterotic and seed rate effects on nitrogen efficiencies in wheat

Four field experiments over 2 years investigated whether wheat hybrids had higher nitrogen-use efficiency (NUE) than their parents over a range of seed rates and different N regimes. There was little heterosis for total N in the above-ground biomass (NYt), but there was high-parent heterosis for grain N yields (NYg) in two of the hybrids, Hyno Esta and Hyno Rista, associated with greater nitrogen harvest index (NHI). Overall, the hybrids did not significantly increase the total dry matter produced per unit N in the above-ground crop (NUtE(t)), but did increase the grain dry matter per unit N in the above ground crop (NUtE(g)). The improvement in NUtE(g) was at the partial detriment of grain N concentration. Heterosis for grain NYg in Hyno Esta was lower at zero-N, suggesting that it did not achieve higher yields through more efficient capture or utilization of N. The greater NHI in Hyno Esta appeared to be facilitated by both greater N uptake, and remobilization of N from vegetative tissues, after anthesis. The response of N efficiency and uptake to seed rate was dependent on N supply and season. Where N fertilizer was applied, N uptake over time was slower at the lower seed rates, but where N was withheld N capture at the lowest seed rate soon approached the N capture of the higher seed rates. During grain filling, the rate of accumulation of N into the grain increased with seed rate and the duration of N accumulation decreased with seed rate. With N applied, N yields increased to all asymptote with seed rate, when N was withheld there was little response of N yields to seed rate. In 2002, N utilization efficiency (NUtE(t) and NUtE(g)) also increased asymptotically with seed rate, but in 2003 seed rate had little effect on N utilization efficiency. When nitrogen fertilizer had not been applied, NHI consistently decreased with increasing seed rate. The timing of N application made little difference to NUE, NY, or NUtE.

Infrared absorption spectra, radiative efficiencies, and global warming potentials of perfluorocarbons: Comparison between experiment and theory

Experimentally and theoretically determined infrared spectra are reported for a series of straight-chain perfluorocarbons: C2F6, C3F8, C4F10, C5F12, C6F14, and C8F18. Theoretical spectra were determined using both density functional (DFT) and ab initio methods. Radiative efficiencies (REs) were determined using the method of Pinnock et al. (1995) and combined with atmospheric lifetimes from the literature to determine global warming potentials (GWPs). Theoretically determined absorption cross sections were within 10% of experimentally determined values. Despite being much less computationally expensive, DFT calculations were generally found to perform better than ab initio methods. There is a strong wavenumber dependence of radiative forcing in the region of the fundamental C-F vibration, and small differences in wavelength between band positions determined by theory and experiment have a significant impact on the REs. We apply an empirical correction to the theoretical spectra and then test this correction on a number of branched chain and cyclic perfluoroalkanes. We then compute absorption cross sections, REs, and GWPs for an additional set of perfluoroalkenes.

Radiative efficiencies and global warming potentials using theoretically determined absorption cross-sections for several hydrofluoroethers (HFEs) and hydrofluoropolyethers (HFPEs)

Integrated infrared cross-sections and wavenumber positions for the vibrational modes of a range of hydrofluoroethers (HFEs) and hydrofluoropolyethers (HFPEs) have been calculated. Spectra were determined using a density functional method with an empirically derived correction for the wavenumbers of band positions. Radiative efficiencies (REs) were determined using the Pinnock et al. method and were used with atmospheric lifetimes from the literature to determine global warming potentials (GWPs). For the HFEs and the majority of the molecules in the HG series HFPEs, theoretically determined absorption cross-sections and REs lie within ca. 10% of those determined using measured spectra. For the larger molecules in the HG series and the HG′ series of HFPEs, agreement is less good, with theoretical values for the integrated cross-sections being up to 35% higher than the experimental values; REs are up to 45% higher. Our method gives better results than previous theoretical approaches, because of the level of theory chosen and, for REs, because an empirical wavenumber correction derived for perfluorocarbons is effective in predicting the positions of C–F stretching frequencies at around 1250 cm−1 for the molecules considered here.

Radiative efficiencies for fluorinated esters: indirect global warming potentials of hydrofluoroethers

Density Functional Theory (DFT) has been used with an empirically-derived correction for the wavenumbers of vibrational band positions to predict the infrared spectra of several fluorinated esters (FESs). Radiative efficiencies (REs) were then determined using the method of Pinnock et al. and these were used with atmospheric lifetimes from the literature to determine the direct global warming potentials of FESs. FESs, in particular fluoroalkylacetates, alkylfluoroacetates and fluoroalkylformates, are potential greenhouse gases and their likely long atmospheric lifetimes and relatively large REs, compared to their parent HFEs, make them active contributors to global warming. Here, we use the concept of indirect global warming potential (indirect GWP) to assess the contribution to the warming of several commonly used HFEs emitted from the Earth's surface, explicitly taking into account that these HFEs will be converted into the corresponding FESs in the troposphere. The indirect GWP can be calculated using the radiative efficiencies and lifetimes of the HFE and its degradation FES products. We found that the GWPs of those studied HFEs which have the smallest direct GWP can be increased by 100-1600% when taking account of the cumulative effect due to the secondary FESs formed during HFE atmospheric oxidation. This effect may be particularly important for non-segregated HFEs and some segregated HFEs, which may contribute significantly more to global warming than can be concluded from examination of their direct GWPs.

The evolution of innovation capability in multinational enterprise subsidiaries: dual network embeddedness and the divergence of subsidiary specialisation in Taiwan

This paper examines how innovation-related capabilities for production, design and marketing develop at the subsidiary level within multinational enterprises (MNEs). We focus on how subsidiary autonomy and changing opportunities to access internal (MNE) and external (host country) sources of capability contribute in a combined way to the accumulation of specialist capabilities in five Taiwan-based MNE subsidiaries in the semiconductor industry. Longitudinal analysis shows how the accumulation process is subject to discontinuities, as functional divisions are (re)opened and closed during the lifetime of the subsidiary. A composite set of innovation output measures also shows significant variations in within-function levels of capability across our sample. We conclude that subsidiary specialisation and unique subsidiary-specific advantages have evolved in a way that is strongly influenced by the above factors.

Bayesian ranking and slection of fishing boat efficiencies

The steadily accumulating literature on technical efficiency in fisheries attests to the importance of efficiency as an indicator of fleet condition and as an object of management concern. In this paper, we extend previous work by presenting a Bayesian hierarchical approach that yields both efficiency estimates and, as a byproduct of the estimation algorithm, probabilistic rankings of the relative technical efficiencies of fishing boats. The estimation algorithm is based on recent advances in Markov Chain Monte Carlo (MCMC) methods— Gibbs sampling, in particular—which have not been widely used in fisheries economics. We apply the method to a sample of 10,865 boat trips in the US Pacific hake (or whiting) fishery during 1987–2003. We uncover systematic differences between efficiency rankings based on sample mean efficiency estimates and those that exploit the full posterior distributions of boat efficiencies to estimate the probability that a given boat has the highest true mean efficiency.

Global warming potentials and radiative efficiencies of halocarbons and related compounds: a comprehensive review

In the mid-1970s it was recognized that, as well as being substances that deplete stratospheric ozone, chlorofluorocarbons (CFCs) were strong greenhouse gases that could have substantial impacts on radiative forcing of climate change. Around a decade later, this group of radiatively active compounds was expanded to include a large number of replacements for ozone-depleting substances such as chlorocarbons, hydrochlorocarbons, hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), bromofluorocarbons, and bromochlorofluorocarbons. This paper systematically reviews the published literature concerning the radiative efficiencies (REs) of CFCs, bromofluorocarbons and bromochlorofluorocarbons (halons), HCFCs, HFCs, PFCs, SF6, NF3, and related halogen containing compounds. In addition we provide a comprehensive and self-consistent set of new calculations of REs and global warming potentials (GWPs) for these compounds, mostly employing atmospheric lifetimes taken from the available literature. We also present Global Temperature change Potentials (GTPs) for selected gases. Infrared absorption spectra used in the RE calculations were taken from databases and individual studies, and from experimental and ab initio computational studies. Evaluations of REs and GWPs are presented for more than 200 compounds. Our calculations yield REs significantly (> 5%) different from those in the Intergovernmental Panel on Climate Change Fourth Assessment Report (AR4) for 49 compounds. We present new RE values for more than 100 gases which were not included in AR4. A widely-used simple method to calculate REs and GWPs from absorption spectra and atmospheric lifetimes is assessed and updated. This is the most comprehensive review of the radiative efficiencies and global warming potentials of halogenated compounds performed to date.

Infrared absorption spectra, radiative efficiencies, and global warming potentials of newly-detected halogenated compounds: CFC-113a, CFC-112 and HCFC-133a

CFC-113a (CF3CCl3), CFC-112 (CFCl2CFCl2) and HCFC-133a (CF3CH2Cl) are three newly detected molecules in the atmosphere that are almost certainly emitted as a result of human activity. It is important to characterise the possible contribution of these gases to radiative forcing of climate change and also to provide information on the CO2-equivalence of their emissions. We report new laboratory measurements of absorption cross-sections of these three compounds at a resolution of 0.01 cm−1 for two temperatures 250 K and 295 K in the spectral range of 600–1730 cm−1. These spectra are then used to calculate the radiative efficiencies and global warming potentials (GWP). The radiative efficiencies are found to be between 0.15 and 0.3 W∙m−2∙ppbv−1. The GWP for a 100 year time horizon, relative to carbon dioxide, ranges from 340 for the relatively short-lived HCFC-133a to 3840 for the longer-lived CFC-112. At current (2012) concentrations, these gases make a trivial contribution to total radiative forcing; however, the concentrations of CFC-113a and HCFC-133a are continuing to increase. The 2012 CO2-equivalent emissions, using the GWP (100), are estimated to be about 4% of the current global CO2-equivalent emissions of HFC-134a

Genetic diversity and specialisation of Eudarluca caricis on some graminaceous Puccinia species

Eudarluca caricis is a common hyperparasite of rusts. A total of 100 cultures were isolated from six Puccinia species or forms growing on 10 species of British grasses at two sites approximately 3 km apart. 82 isolates collected in 2005 were partially sequenced at the ITS locus, and amplified fragment length polymorphism profiles generated for 86 isolates from 2005 and 12 from 2007. Partial ITS sequences of most isolates grouped closely, in a clade with previously reported graminaceous Puccinia isolates and a number of Melampsora isolates. A second clade was very distinct and contained mostly isolates from P. poarum on Poa trivialis. All isolates had distinct AFLP haplotypes. The P. poarum isolates were very distinct from isolates collected from other rusts at the same site. Isolates from P. brachypodii f. sp. arrehenatheri growing on Arrhenatherum elatius in 2005 and 2007 at the same location were distinct (P < 0.001). Isolates from each rust or grass in one year and site were more similar than expected from overall variation between isolates (P<0.001). Isolates from P. coronata on different grasses clustered together (with isolates from P. brachypodii f. sp. poae-nemoralis), suggesting partial host rust specialisation in E. caricis.