Herbicides are the main source of weed control for the majority of soybean growers (Buhler and Hartzler, 2004). The most widely used class of pesticides in the UnitedStates are herbicides (Plimmer, 2003). Prior to herbicides, weedmanagement was achieved through cultivation and hand removal (Fernandez-Cornejo et al., 2014). In 1952, only 10 percent of corn acres were treated with herbicides. By 1976, 90 percent of the corn planted in the U.S. was being treated with herbicides. Soybeans experienced a similar expansion of herbicide use during the same time frame in the U.S. (Figure 1). UnitedStatessoybean acres increased dramatically, between 1960 and 1981, from 24.4 million acres to 67.5 million acres. This is a more dramatic increase than any other U.S. row crop during that era. During this time (1960-80), an increase in herbicide use on soybean acres was documented as 0.1 lb/A of active ingredient being used in 1960 compared to 2.1 lbs/A of active ingredient applied in 1981. The source of these figures were from pesticide use surveys completed by UnitedStates Department of Agriculture (USDA), National Agricultural Statistics Service (NASS), and proprietary data from the Economic Research Service (ERS) (Fernandez-Cornejo et al., 2014).
Origin and evolution of deltacoronaviruses. In general, CoVs have high mutation rates and can easily undergo recombination and deletion events that lead to altered tissue tropism, transmis- sion routes, and host specificity. Birds are reservoirs for avian deltacoronaviruses (15–17). These avian deltacoronaviruses may adapt and jump to some mammalian species. Interestingly, the first mammalian source of deltacoronavirus was detected in rectal swabs of Asian leopard cats at live-animal markets in Guangdong and Guangxi Provinces in China (23). It was found that 2.4% of Asian leopard cats (35 out of 1,453 samples) were positive for deltacoronavirus. It was also found that 1.1% of Chinese ferret- badgers (11 out of 934 samples) were also positive for deltacoro- navirus, which shares 100% homology with the Asian leopard cat CoV based on the RdRp domain and the S gene sequence (23). Interestingly, the PdCVs of both Hong Kong strains and U.S. iso- lates share more homology with deltacoronaviruses of Asian leopard cats and Chinese ferret-badgers than avian deltacorona- viruses, suggesting that Asian leopard cats and Chinese ferret- badgers are intermediates for interspecies transmission of PdCV. At this time, we do not know if deltacoronaviruses are present in U.S. bird populations or other U.S. mammals (such as domestic cats). Clearly, a better understanding of the origin and evolution of the U.S. PdCV will await the detailed epidemiological study of deltacoronaviruses in the birds and mammals in the UnitedStates. PdCV in Gn piglets: similarities with PEDV and TGEV. We have shown that both the PdCV Ohio CVM1 and MI strains in- duce significant disease in Gn pigs. The pathogenesis of TGEV and PEDV is well studied. Both TGEV and PEDV are members of the Alphacoronavirus genus and cause almost identical clinical signs and gross and histological lesions in young, susceptible pigs (6, 12, 24, 26), even though there is no serological cross-reactivity be- tween TGEV and PEDV. In contrast, PdCV is a member of the genus Deltacoronavirus most closely related to avian CoVs (15). The overall clinical disease associated with PdCV infection is very similar to that induced by TGEV and PEDV, except that vomiting is more commonly seen in PdCV-infected piglets and the mortal- ity rates are reported to be lower (on the order of 40 to 50%) than those for PEDV and TGEV (90 to 100%). Similar to TGEV and PEDV, PdCV replicates extensively in the small intestine. High levels of genomic RNA were detected in feces, intestinal contents,
The focus of this study is a state-by-state comparison of middle school science standards on evolution in the UnitedStates. In 2009, Louise Mead and Anton Mates reviewed the high school science standards on evolution, giving each state a grade based on multiple factors including the number of times the word “evolution” is mentioned, the types of evolution covered, and the inclusion of creationist jargon (Mead and Mates in Evol Educ Outreach 2:359, 2009). Their study was a replication of an earlier one completed in 2000 by Lawrence Lerner and the Thomas B. Fordham Founda- tion (Lerner in Good science, bad science: teaching evolution in the states. Thomas Fordham Foundation, Washing- ton, 2000). Mead and Mates indicated that, on average, the quality of the standards had increased over the decade between studies. This study concludes that this positive trend is now evident in the middle school science standards across the nation. We propose that early evolutionary education will be an excellent indicator of future acceptance of evolution across the UnitedStates and strongly encourage that evolution be introduced as the underlying theme of biology early in a student’s academic career.
This study investigated the views of Pakistani-American medical doctors regarding biological evolution. We used a mixed-methods approach, chiefly consisting of a short interview that presented evolution in the contexts of microbial, animal, and human evolution; evolution's acceptability or unacceptability to Muslims; and evolution's relevance to medicine. The participants were 23 doctors attending a convention in the UnitedStates. Fourteen participants accepted evolution, three rejected evolution, and six held other views. While a majority of participants indicated that they accepted evolution, a slightly smaller plurality accepted human evolution. A majority of participants, including some who did not wholly accept or reject evolution, thought that one could mutually accept evolution and also believe in Allah. Nearly every participant, including two who rejected evolution, thought that evolution was relevant to medicine. We find that participants assigned a plurality of meanings to the theory that depended on interactions between a participant ’ s perception of religion, science, medicine, and a host of other cultural influences. This study is the first of a collection of studies carried out by the authors, who collected data with the same instrument in five other countries with significant populations of Muslim doctors and medical students.
The gradual, incremental, group-by-group expansion of in ﬂ uenza rec- ommendations to additional age and risk groups was challenging for providers and the public. In the ensuing years, immunization experts, professional organizations, and other stakeholders debated the ad- vantages and challenges of expanding routine in ﬂ uenza vaccination to all persons in the UnitedStates. 8 – 10 At a meeting of immunization and
Gross domestic product (GDP) per capita may act as both a proxy and as an influence on the world view of a populace. We posit that the populace in countries with low GDPs, with limited economic and industrial devel- opment, have limited access to formal and informal sci- ence education and opportunities to engage in learning about the scientific perspective of biological evolution (Jaumotte et al. 2008). The relationship between evolu- tion acceptance and GDP per capita was found to be the case when considered on an international scale (Heddy & Nadelson, 2012). Once again, the US appears to be an anomaly. The US is one of the most advanced countries in the world with a comparatively high GDP per capita. Despite its apparent superior GDP per capita, the US maintains a relatively low level of public acceptance of evolution. However, the country level data may not be particularly useful when exploring different regions of the US due to uneven wealth distribution.
There has been extensive development in the credit-risk literature since Black and Scholes (1973) and Merton (1974) published their pioneering works. Two basic approaches have been proposed to model corporate default risk. The first approach, known as the structural approach, defines default as occurring either at maturity (Merton 1974) or when the firm's asset value falls below a pre-specified threshold level (Kim, Ramaswamy, and Sundaresan 1992, Leland 1994, and Longstaff and Schwartz 1995). This approach has been applied in Merton (1974), Cooper and Mello (1991), and many other studies. An attractive feature of these models is that they explain the default time of a company in terms of firm-specific variables. One critical assumption of these models, however, is that the evolution of firm value follows a diffusion process. Since a diffusion process does not allow a sudden drop in firm value, the probability of the firm defaulting in the near term is negligible (Duffie and Lando 2001). Therefore, these models generate near-zero credit spread for short-term debt, which is strongly rejected by empirical evidence (Jones, Mason, and Rosenfeld 1984). Alternatively, Zhou (1997) obtains positive short-term credit spreads by modelling the asset value as a jump-diffusion process. This comes at the cost of tractability, since multiple jumps must be allowed to determine the asset value.
During 1998, severe outbreaks of influenza were observed in four swine herds in the UnitedStates. This event was unique because the causative agents, H3N2 influenza viruses, are infrequently isolated from swine in North America. Two antigenically distinct reassortant viruses (H3N2) were isolated from infected animals: a double- reassortant virus containing genes similar to those of human and swine viruses, and a triple-reassortant virus containing genes similar to those of human, swine, and avian influenza viruses (N. N. Zhou, D. A. Senne, J. S. Landgraf, S. L. Swenson, G. Erickson, K. Rossow, L. Liu, K.-J. Yoon, S. Krauss, and R. G. Webster, J. Virol. 73:8851–8856, 1999). Because the U.S. pig population was essentially naive in regard to H3N2 viruses, it was important to determine the extent of viral spread. Hemagglutination inhibition (HI) assays of 4,382 serum samples from swine in 23 states indicated that 28.3% of these animals had been exposed to classical swine-like H1N1 viruses and 20.5% had been exposed to the triple-reassortant-like H3N2 viruses. The HI data suggested that viruses antigenically related to the double-reassortant H3N2 virus have not become widespread in the U.S. swine population. The seroreactivity levels in swine serum samples and the nucleotide sequences of six additional 1999 isolates, all of which were of the triple-reassortant genotype, suggested that H3N2 viruses containing avian PA and PB2 genes had spread throughout much of the country. These avian-like genes cluster with genes from North American avian viruses. The worldwide predominance of swine viruses containing an avian-like internal gene component suggests that these genes may confer a selective advantage in pigs. Analysis of the 1999 swine H3N2 isolates showed that the internal gene complex of the triple-reassortant viruses was associated with three recent phylogenetically distinct human-like hemagglutinin (HA) molecules. Acquisition of HA genes from the human virus reservoir will significantly affect the efficacy of the current swine H3N2 vaccines. This finding supports continued surveillance of U.S. swine populations for influenza virus activity.
HI data (Table S2) were used to characterize the antigenic re- lationships of contemporary swine H1 viruses by antigenic cartography, focusing on the human-seasonal derived H1- δ viruses (Figs. 2 and S3). These data allow the calculation of antigenic distance between all pairs of antigens, with more than 2 AU between strains considered signi ﬁ cant (1 AU is equivalent to a 2-fold di ﬀ erence in HI titer). Due to the anti- genic diversity observed for the H1 viruses, antigenic clusters were separated based on genetic clades for improved visualization. For each antigenic cluster, the most centrally located strain with antigenic dis- tances < 2 AU to the highest number of strains in that cluster was chosen as the antigenic reference strain. Overall, δ-clade viruses de- monstrated limited cross-reactivity within each clade (H1- δ 1/1B.2.2 or H1- δ 2/1B.2.1), yet showed a trend to be mapped in accordance with their evolution (Figs. 2A and S3). The H1-δ1 clade (1B.2.2) was the most antigenically diverse group, and the newly emerging H1- δ 1a (1B.2.2.1) and H1- δ 1b (1B.2.2.2) clades showed reduced cross-re- activity with older H1-δ1 (1B.2.2) and between each other (average within clade distance of 2.9 – 3 AU, and between clades of 3.2 AU). Strains of the δ -clades collected after 2012 were more antigenically diverse, with antigenic distance from the representative strain ranging from 0.4 to 4.6, and most outliers were identiﬁed among these (Fig. 2A, C – E). Classical swine-lineage H1 viruses as well as H1N1pdm09 (1A.3.3.2) were clustered antigenically according to their genetic clades, with relatively stronger cross-reactivity within a clade (average within clade distance of 1 – 2.4 AU). The classical swine lineage and pandemic strains formed a separate antigenic group from the H1-δ viruses (Fig. S3).
the UnitedStates to take regional initiatives. Concerns over the U.S. expansion led Europeans to agree to new multilateral negotiations while the stalemate of the Uruguay Round offered the UnitedStates, Canada and Mexico the opportunity to conclude the NAFTA. Subsequently, after the failure of the Doha Development Round, the UnitedStates saw in free trade agreements more than a second best approach to trade liberalization, an opportunity to broaden trade liberalization to the global level and influence the content of future international trade rules. 8 Griffith,
Herbicide tolerant and insect resistant crop varieties like Roundup Ready® (RR) soybean and Bt corn have now been in use for over a decade in the U.S. In 2008, the UnitedStates Department of Agriculture’s National Agricultural Statistics Service reported that 80 percent of corn, 86 percent of cotton, and 92 percent of soybean acreage in the U.S. was planted with either herbicide tolerant, insect resistant, or a combination of herbicide tolerant and insect resistant varieties. Such rapid adoption of a new technology suggests that growers perceive significant benefits. Marra et al.’s (2002) review of the literature generally supports this hypothesis, though there are a few cases where benefit estimates do not always appear to favor the new varieties over their conventional counterparts (see for example Duffy and Ernst, 1999; and Fernandez- Cornejo and McBride, 2002). Even though the weight of evidence suggests the new varieties currently provide substantial benefits to growers, critics contend that these benefits may be short- lived because adoption can lead to unsustainable production practices (e.g. Benbrook, 2001). Therefore, it seems prudent to regularly monitor the benefits provided by these new crop varieties and to explore how the adoption of production practices to promote sustainability may enhance these benefits.
Soybean sudden death syndrome (SDS) is a fungal disease causing foliar necrosis and early leaf drop. SDS can be a significant factor in soybean yield loss and has been found in fields across Iowa. The fungus is a good saprophyte and can grow well on plant debris in the field. The disease often is worse following corn. Although there is no complete resistance to SDS available in soybean, disease resistance is an important part of SDS disease management.
Herbicide resistance has become a critical issue to growers in the developed world such as North America, Europe and Australia. There have been no new herbicide mechanisms of action introduced since 1992 and multiple-resistant weeds are reducing the number of herbicides available to control some of the most common and troublesome weeds in certain cropping areas such as Amaranthus in North America, Alopecurus in Western Europe, and Lolium in Australia (V ENCILL et al., 2012). There are newer herbicide-resistant crop technologies being developed such as auxinic-resistant cotton and soybean. Under this scenario, it would be most beneficial to weed scientists and others to have a better understanding of what herbicide-weed-management scenarios; herbicide-resistant weeds are most likely to develop.This paper will present a framework for determining the potential for herbicide resistance development under given weed, herbicide, and management conditions.
Host-plant resistance offers an additional comple- mentary management tactic in an overall integrated pest management program. More than 3500 soybean acces- sions were screened, resulting in the identification of only 30 soybean accessions with either antixenosis- and/ or antibiosis-type resistance to the soybean aphid (Hill et al., 2004a,b; Mensah et al., 2005; Diaz-Montano et al., 2006; Mian et al., 2008a; Jun et al., 2012; Bansal et al., 2013; Fox et al., 2014; Hesler et al., 2013; Jun et al., 2013; Kim et al., 2014; Xiao et al., 2013; Bhusal et al., 2014; Liu et al., 2014). Antixenosis-based resistance refers to a nonpreference of insects for behaviors like feeding and oviposition that can result in the poor establishment of an insect (Smith, 1989). Antibiosis-based resistance refers to an adverse effect of the host plant on the insect sur- vival, development, and reproduction often exhibited by larval death or abnormal larval growth (Smith, 1989). A number of independent aphid resistance Rag (resistance to Aphis glycines) genes have been mapped and described, including: Rag1 (Hill et al., 2006a,b; Li et al., 2008), Rag2 (Kang et al., 2008; Mian et al., 2008b), rag1c, rag4 (Zhang et al., 2009), and Rag3 (Zhang et al., 2010). Rag1 was identified in the soybean cultivar Dowling and pro- vides strong antibiosis-type resistance; it is a single domi- nant gene and maps to soybean linkage group (LG) M or chromosome 7 (Li et al., 2004; Hill et al., 2006a; Li et al., 2008). An unnamed Rag gene was initially identi- fied in cultivar Jackson; it is also a single dominant gene that maps to the same genomic region and is allelic to Rag1 (Hill et al., 2012). Antibiosis-based resistance was also identified in plant introduction (PI) 567541B and PI 567598B and was found to be controlled by two recessive genes (Mensah et al., 2005; Mensah et al., 2008). The rag1c and rag4 genes from PI 567541B were mapped to LG M and LG F (chromosome 13), respectively. Rag1 and rag1c mapped to a similar region on LG M, but the allelic rela- tionship is unknown. Rag2 confers antibiosis and was dis- covered independently in two accessions, PI 243540 and PI 200538, and maps to LG F (Kang et al., 2008; Mian et al., 2008b; Hill et al., 2009). Meng (2010) identified
Minnesota and portions of Iowa, North Dakota, and South Dakota (R.L.K., B.D.P., E.W.H., J.J.K., and A.J.V., personal observations), while such infestations have diminished in other parts of the UnitedStates (Bahlai et al. 2015). This pattern of greater pest pressure in Minnesota and neighboring states is further evidenced by data from NASS (2018). Over recent years, the percentage of soybean acres that have been treated with insecticides, not including seed treat- ments, has been highest in Minnesota, followed by Iowa and North Dakota compared to other states in the Midwest Region (Fig. 2). Similarily, a higher percentage of soybean acres has been scouted for arthropod pests in Minnesota, Iowa, and North Dakota than in other states in the region (Fig. 2). These continued infestations by soybean aphid in parts of the Upper Midwest have resulted in a long history (i.e., about 17 yr) of selection pressure for develop- ment of insecticide resistance. In particular, the area of southwest Minnesota (i.e., Blue Earth, Brown, Cottonwood, Faribault, Martin, Redwood, Renville, and Watonwan counties) from which pyrethroid performance issues were first reported (Hanson et al. 2017) has had chronically high soybean aphid populations (i.e., exceeding the eco- nomic threshold) every year, except 2003. This area of Minnesota also receives significant numbers of pyrethroid insecticide applica- tions to canning crops, which are often adjacent to soybean.
Consequently, the utilization of these screenable characteristics could be positively evaluated in breeding programs with the aim of developing high competitive chickpea cultivars. However, the competitive advantage for the crops does not only rely on species characteristics, for instance in chapter 5.c. and 5.d. the transplanting of pepper seedlings represents a means for establishing the desired initial size differences between crop and weeds. Furthermore an evaluation of a weed control strategy should not only be focused on weedmanagement aspects, but should also be useful for adjusting the whole crop management. Chapter 5.c. illustrates that the mulching of hairy vetch residues combined with an inter-row tillage could enable us to obtain a satisfactory pepper yield and reduces the requirement of external inputs such as herbicides and fertilizers, as well as allowing an efficient weed control throughout the pepper cropping period. Finally, it is also important to evaluate the effects of a weedmanagement strategy over time. Considering that the weed community composition varies in a cyclic way during crop rotation, this enable us to identify typical weed community trajectories during crop rotation and therefore to better comprehend the differences in the weed species among the ecological weedmanagement strategies adopted in each crop. Chapter 5.a. illustrates how key weeds (P. aviculare in the specific case) cause severe yield loss on chickpea with few plants per unit area, probably due to its ability to compete for limited resources. It is widely accepted that conserving farmland biodiversity has become an fundamental issue for maintaining ecological functions in intensively managed agro-ecosystems. The use of ecological weedmanagement strategies causes a significant change in weed community composition and species diversity. Chapter 5.d. suggests that the cover crop residues converted into mulch strips can represent a more sustainable approach because they reduce the weed density and consequently increase the pepper yield while maintaining a high level of weed diversity indices and evenness achieving a low agro-ecosystem disturbance.