Sugar concentration in nectar: a quantitative metric of crop attractiveness for refined pollinator risk assessments

Those involved with pollinator risk assessment know that agricultural crops vary in attractiveness to bees. Intuitively, this means that exposure to agricultural pesticides is likely greatest for attractive plants and lowest for unattractive plants. While crop attractiveness in the risk assessment process has been qualitatively remarked on by some authorities, absent is direction on how to refine the process with quantitative metrics of attractiveness. At a high level, attractiveness of crops to bees appears to depend on several key variables, including but not limited to: floral, olfactory, visual and tactile cues; seasonal availability; physical and behavioral characteristics of the bee; plant and nectar rewards. Notwithstanding the complexities and interactions among these variables, sugar content in nectar stands out as a suitable quantitative metric by which to refine pollinator risk assessments for attractiveness. Provided herein is a proposed way to use sugar nectar concentration to adjust the exposure parameter (with what is called a crop attractiveness factor) in the calculation of risk quotients in order to derive crop‐specific tier I assessments. This Perspective is meant to invite discussion on incorporating such changes in the risk assessment process. © 2016 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Pathogenic profile and cytotoxic activity of Aeromonas spp. isolated from Pectinatella magnifica and surrounding water in the South Bohemian aquaculture region

Pectinatella magnifica is an invasive freshwater bryozoan that has expanded in many localities worldwide, including fishing areas. It contains microbial communities, predominantly consisting of Aeromonas bacteria that are frequently associated with fish infections. The objective of this study was to investigate the potential pathogenicity of Aeromonas spp. associated with P. magnifica and evaluate the health risks for fish. Aeromonas strains were isolated from P. magnifica (101 strains) and from surrounding water (29 strains) in the South Bohemian region and investigated for the presence of 14 virulence-associated genes using PCR. We demonstrated high prevalence of phospholipase GCAT, polar flagellin, enolase, DNAse, aerolysin/cytotoxic enterotoxin, serine protease and heat-stable cytotonic enterotoxin-coding genes. Further, all twelve isolates that were analysed for cytotoxicity against intestinal epithelial cells were found to be cytotoxic. Six of the isolates were also tested as co-cultures composed of pairs. Enhanced cytotoxicity was observed when the pair was composed of strains from different species. In conclusion, P. magnifica is colonized by Aeromonas strains that have a relatively high prevalence of virulence-associated genes and the ability to provoke disease. Results also suggest a possibly increased risk arising from mixed infections.     

Immobilization of free-ranging maned wolf (Chrysocyon brachyurus) with tiletamine and zolazepam in central Brazil.

A tiletamine hydrochloride-zolazepam hydrochloride combination was used successfully to immobilize 27 free-ranging maned wolves (Chrysocyon brachyurus) at a mean dose of 2.77+/-0.56 (mean+/-SD) mg/kg. The induction time ranged from 3-15 min. Animals remained immobilized for periods of 48.56 +/-12.65 min. Compulsive licking, excessive salivation, muscle twitching, muscle tremors, tachypnea, and bradycardia were observed associated with the induction of the anesthesia in 13 of 27 maned wolves. Muscle twitching, pedal withdrawal reflex, muscle tremors, and ataxia were observed during recovery in three (11%) maned wolves. There were no significant differences in heart rates (P = 0.44), respiratory rates (P = 0.82), and rectal temperatures (P = 0.54) recorded at 5, 15, and 25 min after induction at these dosages. The tiletamine hydrochloride-zolazepam hydrochloride combination was shown to be an effective and safe immobilizing agent for free-ranging maned wolves.     

Wild rabies virus detection by plaque assay from naturally infected brains in different species

A simple, sensitive and specific plaque assay protocol for the detection of wild type rabies virus in different species is described using confluent monolayers of chicken embryo cells in 6-well plates. Plaques are produced after application of either agarose or Sephadex G-100 overlay onto cell monolayers and incubation for 96 h after virus infection at 37 degrees C. The parameters affecting plaque appearance include cell seeding concentration, overlay composition and time of incubation after infection. Optimal conditions are seeding at a concentration of 4 x 10(6) cell/cm(3), incubation at 37 degrees C in 5% CO(2) atmosphere during 96 h, using either 1% agarose or 2% Sephadex G-100 overlays. The described plaque assay would be a new valuable tool in conducting various quantitative investigations, since the chicken embryo cells are susceptible to rabies virus infection from all species studied.     

Comparison of selected indices of internal environment and condition of laying hens kept in furnished cages and in aviaries

Biochemical and hematological examination of blood and individual assessment of the birds were performed in Lohman Brown laying hens at 45 weeks of age housed in different systems. The biochemical examination revealed higher (p < .01) corticosterone levels, creatine kinase, and aspartate aminotransferase activity and lower (p < .01) levels of lactate, triglycerides, albumin, calcium, and phosphorus in aviary hens compared to hens housed in furnished cages. Hematological examination of hens housed in aviaries revealed higher (p < .05) hematocrit, leukocytes, heterophils, eosinophils, basophils, monocytes, and H/L ratio. Furthermore, hens housed in aviaries had lower (p < .01) body weight than hens in furnished cages, they were worse feathered (p < .001), had more damaged combs (p < .05), and poorer physical condition (p < .01). In contrast, caged hens showed worse (p < .01) feather condition of the wings due to abrasion and claws due to overgrowth. The results have shown that the housing system has a significant impact on the internal environment and condition of birds and that housing in aviaries without taking into account the specifics of such housing may lead to significant stress and disturbance to the welfare of laying hens.     

Spatial delineation of organic carbon-rich Colluvial soils in Chernozem regions by Terrain analysis and fuzzy classification

Colluvial soils are considered to be the direct result of accelerated soil erosion, resulting in accumulation of humus-rich soil material in terrain depressions and base parts of slopes. The organic carbon concentration in these soils and their depth make them an important organic carbon storage. Mapping the Colluvial soils, therefore, represents an important contribution in total carbon stock estimation. A method of delineating Colluvial soils is proposed by applying a combination of high resolution digital elevation model analysis and detailed field survey. Two models based on fuzzy classification of soil units were created using different topographic derivatives as the only input parameters to predict the Colluvial soil area on a morphologically diverse study site in the Southern Moravia, Czech Republic. The model that considers only the derivatives with a strong relationship to Colluvial soil occurrence reached 71% accuracy in Colluvial area delineation, while the model combining six commonly used derivatives showed less favorable results. The main advantage of the method lies in a low demand of input soil data and its relatively high accuracy.     

Economical and financial analysis of lamb finishing fed with diets formulated according to the NRC (1985) and the NRC (2007)

This study compares both versions of the nutritional requirement system determined by the National Research Council (NRC) version 1985 (NRC85) and NRC version 2007 (NRC07), for finishing lambs in feedlots. Nineteen crossbred lambs were divided in four groups representing four experimental treatments: one diet according to NRC85 and three diets according to NRC07. The diets recommended by NRC07 considers crude protein intake relative to ruminal undegradable protein at 20, 40, and 60 % levels (NRC07/20, NRC07/40, and NRC07/60). Diets were composed of Brazilian semi-arid native grass silage, soybean meal, corn, annatto byproduct, and limestone. Purchases and sales of lambs were done according to average market prices in Brazil. The economic indicators considered pointed that all treatments were viable but NRC07/20 and NRC07/60 were more profitable with similar net present values (NPVs) and internal return rates (IRRs). NRC07/20 was the best option showing an IRR of 17.20 % and a payback period (PP) of 5.07 considering a fixed annual interest rate of 6 %. Sensitivity analysis considering a 10 % raise in variable costs showed negative NPVs, IRRs inferior to the opportunity cost rates adopted and PPs that exceeded the planning horizon of 7 years for both NRC85 and NRC07/40.     

Use of trichostatin A alters the expression of HDAC3 and KAT2 and improves in vitro development of bovine embryos cloned using less methylated mesenchymal stem cells

The aim of this work was to investigate the methylation and hydroxymethylation status of mesenchymal stem cells (MSC) from amniotic fluid (MSC‐AF), adipose tissue (MSC‐AT) and fibroblasts (FIB‐control) and to verify the effect of trichostatin A (TSA) on gene expression and development of cloned bovine embryos produced using these cells. Characterization of MSC from two animals (BOV1 and BOV2) was performed by flow cytometry, immunophenotyping and analysis of cellular differentiation genes expression. The cells were used in the nuclear transfer in the absence or presence of 50 nM TSA for 20 hr in embryo culture. Expression of HDAC1, HDAC3 and KAT2A genes was measured in embryos by qRT‐PCR. Methylation results showed difference between animals, with MSC from BOV2 demonstrating lower methylation rate than BOV1. Meanwhile, MSC‐AF were less hydroxymethylated for both animals. MSC‐AF from BOV2 produced 44.92 ± 8.88% of blastocysts when embryos were exposed to TSA and similar to embryo rate of MSC‐AT also treated with TSA (37.96 ± 15.80%). However, when methylation was lower in FIB compared to MSC, as found in BOV1, the use of TSA was not sufficient to increase embryo production. MSC‐AF embryos expressed less HDAC3 when treated with TSA, and expression of KAT2A was higher in embryos produced with all MSC and treated with TSA than embryos produced with FIB. The use of MSC less methylated and more hydroxymethylated in combination with embryo incubation with TSA can induce lower expression of HDAC3 and higher expression of KAT2A in the embryos and consequently improve bovine embryo production.     

Comparison of approaches towards ecotoxicity evaluation for the application of dredged sediment on soil

Purpose

The toxicity of 36 dredged sediments from the Czech Republic was investigated using a large battery of bioassays. The aim of this study was to investigate the feasibility of ecotoxicity testing in general and of individual bioassays more specific and to investigate how the results of bioassays are determined by the physicochemical properties of sediment samples and/or sediment contamination.

Material and methods

In 2008 and 2010, 36 sediment samples were collected from rivers and ponds and from sediment heaps in different parts of the Czech Republic. Both their physicochemical properties and their levels of contamination with POPs and heavy metals were analyzed. The ecotoxicities of the sediments were evaluated using the four bioassays from the new Czech directive 257/2009 Coll. concerning the application of dredged sediments on agricultural land (Enchytraeus crypticus reproduction, Folsomia candida reproduction, Lactuca sativa root elongation, and potential ammonium oxidation). The results of the four directive bioassays were compared with the results of other soil bioassays (Caenorhabditis elegans mortality, Eisenia fetida avoidance and reproduction) and eluate bioassays (Daphnia magna immobilization, Pseudokirchneriella subcapitata growth inhibition test, and Vibrio fischeri luminescence).

Results and discussion

We demonstrate that the battery suggested in Czech directive 257/2009 Coll. is highly effective in identifying toxic samples; these bioassays clearly revealing different types of toxicity and different exposure routes. Shorter alternative bioassays may be added especially when fast toxicity identification is needed. Eluate bioassays identified samples potentially hazardous to aquatic ecosystems. Their inclusion into the assessment scheme should be considered if the goal of assessment is also the protection of aquatic ecosystems. The results of our multivariate analysis show that specific physicochemical properties and contamination may affect bioassay responses. C. elegans was the most sensitive bioassay to physicochemical properties and also to organic contamination, while eluate bioassays were sensitive to heavy metal pollution.

Conclusions

Most effects detected by the bioassays could not be explained by the levels of toxicants measured or by the natural characteristics of sediments. Our results show that bioassays are irreplaceable in dredged sediment risk assessment because they complement information provided by chemical analyses.