Effectiveness and chemical pest control of Bt-cotton in the Yangtze River Valley, China

The paper determines what might be the factors beneath the limited or reduced effectiveness being observed in China. The analysis is based on the data collected for several years from many locations in the Yangtze River Valley Varietal Experiment Network. All varieties declared to be Bt-cotton were confirmed to have the Bt-gene, the expression of which was assessed in three ways: through the analysis of Bt-protein production and through indoor and outdoor bioassays. Gene expression varied substantially between varieties and between years for the few varieties which were tested in two subsequent years. The Bt-cotton varieties being sown cannot control bollworms totally and this led to spray chemicals regardless of the real infestation level. Farmers are hence paying high prices for varieties which are not totally resistant to bollworms and pest control costs are not reduced to the extent that they might expect, lowering the profitability of cotton production.     

The structure of the upper atmosphere of mars: In situ accelerometer measurements from mars global surveyor

The Mars Global Surveyor (MGS) z-axis accelerometer has obtained over 200 vertical structures of thermospheric density, temperature, and pressure, ranging from 110 to 170 kilometers, compared to only three previous such vertical structures. In November 1997, a regional dust storm in the Southern Hemisphere triggered an unexpectedly large thermospheric response at mid-northern latitudes, increasing the altitude of thermospheric pressure surfaces there by as much as 8 kilometers and indicating a strong global thermospheric response to a regional dust storm. Throughout the MGS mission, thermospheric density bulges have been detected on opposite sides of the planet near 90 degreesE and 90 degreesW, in the vicinity of maximum terrain heights. This wave 2 pattern may be caused by topographically-forced planetary waves propagating up from the lower atmosphere.     

Expression of lactoferrin in the boar epididymis: effects of reduced estrogen

Lactoferrin is regulated by estrogen in the female reproductive tract and evidence in immature mice suggests that it may be estrogen regulated in males as well. The estrogen regulation of lactoferrin in the epididymis of the boar, a high estrogen-producing male, is unknown. This study was designed to test the hypothesis that lactoferrin expression in the boar epididymis is regulated by estrogen. Twenty-one littermate pairs of boars were treated with vehicle or Letrozole, an aromatase inhibitor, from 1 week of age until castration at 2 through 8 months. Epididymal tissue was collected at castration and fixed for immunolocalization of lactoferrin. Epididymal and testicular tissues were also collected from five mature boars (1-2.5 years) and fixed for immunocytochemistry (ICC). Lactoferrin was localized in the principal cell cytoplasm of the caput, corpus and cauda of developing boars but only in the corpus and cauda of mature boars. Basal cells were negative for lactoferrin. Sperm in the corpus and cauda was also positive for lactoferrin. The efferent ducts and testes were negative for lactoferrin. Intensity of lactoferrin immunostaining increased with age in the corpus and cauda regardless of treatment. Reduced endogenous estrogen in the epididymis during development did not affect the intensity of immunostaining between control and Letrozole-treated animals. Lactoferrin expression in the epididymis of the developing boar does not appear to be regulated by estrogen.     

A repeated cross‐sectional study of the epidemiology of Campylobacter and antimicrobial resistant Enterobacteriaceae in free‐living Canada geese in Guelph,Ontario, Canada

From May through October 2016, we conducted a repeated cross‐sectional study examining the effects of temporal, spatial, flock and demographic factors (i.e. juvenile vs. adult) on the prevalence of Campylobacter and antimicrobial resistant Enterobacteriaceae among 344 fresh faecal samples collected from Canada geese (Branta canadensis) from four locations where birds nested in Guelph, Ontario, Canada. The overall prevalence of Campylobacter among all fresh faecal samples was 9.3% and was greatest in the fall when these birds became more mobile following the nesting season. Based on 40 gene comparative genomic fingerprinting (CGF40), the increase in prevalence noted in the fall was matched by an increase in the number of unique CGF40 subtypes identified. Resistance to colistin was detected most commonly, in 6% of Escherichia coli isolates, and was highest in the late summer months. All colistin‐resistant isolates were negative for the mcr‐1 to mcr‐5 genes; a chromosomal resistance mechanism (PmrB) was identified in all of these isolates. The prevalence of samples with E. coli exhibiting multi‐class resistance or extended spectrum beta‐lactamase was low (i.e. <2% of samples). The intra‐class correlation coefficients, estimated from the variance components of multilevel logistic regression models, indicated that the shedding of Campylobacter and antimicrobial resistant E. coli among geese within a flock (i.e. birds collected from the same site on the same day) was moderately correlated. Spatial, temporal, and spatiotemporal clusters identified using the spatial scan statistic, largely supported the findings from our multi‐level models. Salmonella was not isolated from any of the fresh faecal samples collected suggesting that its prevalence in this population of birds was very low.     

Salmonella,Campylobacter, Clostridium difficile,and anti‐microbial resistant Escherichia coli in the faeces of sympatric meso‐mammals in southern Ontario,Canada

The role of free‐ranging wildlife in the epidemiology of enteropathogens causing clinical illness in humans and domestic animals is unclear. Salmonella enterica and anti‐microbial resistant bacteria have been detected in the faeces of raccoons (Procyon lotor), but little is known about the carriage of these bacteria in other sympatric meso‐mammals. Our objectives were to: (a) report the prevalence of Salmonella and associated anti‐microbial resistance, Campylobacter spp, Clostridium difficile, and anti‐microbial resistant Escherichia coli in the faeces of striped skunks (Mephitis mephitis) and Virginia opossums (Didelphis virginiana) in southern Ontario; and (b) compare the prevalence of these bacteria in the faeces of these meso‐mammal hosts with raccoons from a previously reported study. Faecal swabs were collected from striped skunks and Virginia opossums on five swine farms and five conservation areas from 2011 to 2013. Salmonella was detected in 41% (9/22) and 5% (5/95) of faecal swabs from Virginia opossums and striped skunks, respectively. None of the Salmonella serovars carried resistance to anti‐microbials. The prevalence of Campylobacter spp., C. difficile, and anti‐microbial resistant E. coli ranged from 6% to 22% in striped skunk and Virginia opossums. Using exact logistic regression, Salmonella was significantly more likely to be detected in faecal swabs of Virginia opossums than skunks and significantly less likely in faecal swabs from skunks than raccoons from a previously reported study. In addition, Campylobacter spp. was significantly more likely to be detected in raccoons than opossums. Salmonella Give was detected in 8/9 (89%) of Salmonella‐positive Virginia opossum faecal swabs. Our results suggest that striped skunks and Virginia opossums have the potential to carry pathogenic enteric bacteria in their faeces. The high prevalence of Salmonella Give in Virginia opossum faecal swabs in this study as well as its common occurrence in other Virginia opossum studies throughout North America suggests Virginia opossums may be reservoirs of this serovar.     

Temporal trends in Giardia occurrence in the Grand River and surrounding tributaries,Waterloo, Ontario (2005–2013), a retrospective analysis of surveillance data

Giardia contamination in the Grand River Watershed (south‐western Ontario, Canada) was monitored from 2005 to 2013 as part of FoodNet Canada. Our study objectives were to describe the temporal pattern of Giardia occurrence and determine whether water quality parameters and bacterial indicators could act as effective markers for Giardia occurrence. Water samples were collected monthly from the Grand River near a drinking water intake point (2005–2013) and also collected intermittently from other areas in the watershed during the study period. Samples were tested for Giardia cysts using the US EPA method 1623. Samples were also tested for chemical and microbial water quality indicators. Univariable and multivariable linear regression models were built to examine whether temporal, water quality and bacterial indicators were associated with Giardia cyst concentration. Giardia cysts were identified in 89% of samples (n = 228), with highest measured concentrations downstream of a waste water treatment plant outfall. Year and season were found to be predictors for Giardia occurrence. Concentrations were significantly higher in the winter and fall compared to the summer, and significantly higher in 2007 compared to other study years. After controlling for season, year and sampling location, dissolved oxygen was the only variable significantly associated with Giardia cyst concentration. Seasonal peaks in Giardia cyst concentrations in samples collected near the intake for the drinking water plant did not align with the seasonal peak in human Giardiasis cases in this region that are reported annually by public health authorities. This suggests that the risk of contracting Giardiasis from treated drinking water in this community is possibly low when the treatment plant is functioning adequately. Instead, waterborne exposure is likely the result of seasonal behaviours surrounding recreational water use. Therefore, the collective findings of our study are important to help inform future risk management studies and guide public health protection policies.     

Contribution of fallow periods between rice crops to seasonal GHG emissions: effect of water and tillage management

ABSTRACT

Irrigated rice cultivation is a major source of greenhouse gas (GHG) emissions from agriculture. Methane (CH₄) and nitrous oxide (N₂O) are emitted not only throughout the growing season but also in the fallow period between crops. A study was conducted for two transition periods between rice crops (dry to wet season transition and wet to dry season transition) in the Philippines to investigate the effect of water and tillage management on CH₄ and N₂O emissions as well as on soil nitrate and ammonium. Management treatments between rice crops included (1) continuous flooding (F), (2) soil drying (D), (3) soil drying with aerobic tillage (D + T), and (4) soil drying and wetting (D + W). The static closed chamber method was used to measure CH₄ and N₂O fluxes.

Soil nitrate accumulated and N₂O was emitted in treatments with soil drying. Nitrate disappeared while ammonium gradually increased after the soil was flooded during land preparation, indicating net nitrogen mineralization. N₂O emissions were highest in both transition periods in D + W (437 and 645 µg N₂O m^?2 h^?1). Methane emissions were significant in only the F treatment. The highest global warming potential (GWP) in the transition between rice crops occurred in F, with CH₄ contributing almost 100% to the GWP. The GWP from other treatments was lower than F, with about 60–99% of the GWP attributed to N₂O emissions in treatments with soil drying. The GWP in the transition between rice crops represented up to 26% of the total GWP from harvest to harvest. This study demonstrates that the transition period can be an important source of GHG emissions with relative importance of CH₄ and N₂O depending on the soil water regime. Therefore, the transition period should not be disregarded when estimating GHG emissions for rice cropping systems.     

The Application of GGE Biplot Analysis for Evaluating Test Locations and Mega-Environment Investigation of Cotton Regional Trials

In the process to the marketing of cultivars, identification of superior test locations within multi-environment variety trial schemes is of critical relevance. It is relevant to breeding organizations as well as to governmental organizations in charge of cultivar registration. Where competition among breeding companies exists, effective and fair multi-environment variety trials are of utmost importance to motivate investment in breeding. The objective of this study was to use genotype main effect plus genotype by environment interaction（GGE） biplot analysis to evaluate test locations in terms of discrimination ability, representativeness and desirability, and to investigate the presence of multiple mega-environments in cotton production in the Yangtze River Valley（YaRV）, China. Four traits（cotton lint yield, fiber length, lint breaking tenacity, micronaire） and two composite selection indices were considered. It was found that the assumption of a single mega-environment in the YaRV for cotton production does not hold. The YaRV consists of three cotton mega-environments： a main one represented by 11 locations and two minor ones represented by two test locations each. This demands that the strategy of cotton variety registration or recommendation must be adjusted. GGE biplot analysis has also led to the identification of test location superior for cotton variety evaluation. Although test location desirable for selecting different traits varied greatly, Jinzhou, Hubei Province, China, was found to be desirable for selecting for all traits considered while Jianyang, Sichuan Province, China, was found to be desirable for none.     

A Multi‐Level Approach for Investigating Socio‐Economic and Agricultural Risk Factors Associated with Rates of Reported Cases of Escherichia coli O157 in Humans in Alberta,Canada

Using negative binomial and multi‐level Poisson models, the authors determined the statistical significance of agricultural and socio‐economic risk factors for rates of reported disease associated with Escherichia coli O157 in census subdivisions (CSDs) in Alberta, Canada, 2000–2002. Variables relating to population stability, aboriginal composition of the CSDs, and the economic relationship between CSDs and urban centres were significant risk factors. The percentage of individuals living in low‐income households was not a statistically significant risk factor for rates of disease. The statistical significance of cattle density, recorded at a higher geographical level, depended on the method used to correct for overdispersion, the number of levels included in the multi‐level models, and the choice of using all reported cases or only sporadic cases. Our results highlight the importance of local socio‐economic risk factors in determining rates of disease associated with E. coli O157, but their relationship with individual risk factors requires further evaluation.     

农户种植转Bt基因抗虫棉效益分析

对河北省6个县245个农户两年的问卷调查材料为依据,对种植转Bt基因抗虫棉和非抗虫棉品种的效果以及不同基因来源、不同代数的转Bt基因抗虫棉品种的成本和收益进行了分析比较。结果表明,在调查所涉及的2002和2003年度,转Bt基因抗虫棉品种的产量、农药成本、总成本和收益都比非抗虫棉品种高。转Bt基因抗虫棉1代种子比转Bt基因抗虫棉2代和3代种子产量高,但是两者收益之间的差异在两个年度有不同的趋势。