scholarly journals Gene-by-environment interactions in agricultural pest management: population effects on diet-Bt interactions in a caterpillar

2020 ◽  
Author(s):  
Carrie Deans ◽  
Gregory Sword ◽  
Spencer Behmer ◽  
Eric Burkness ◽  
Marianne Pusztai-Carey ◽  
...  
Keyword(s):  
Helicoverpa Zea ◽  
Control Strategies ◽  
Laboratory Strain ◽  
Population Level ◽  
Nutrient Content ◽  
Pest Species ◽  
Nutrient Regulation ◽  
Cry Toxin ◽  
And Performance ◽  
The Impact

AbstractGiven that plant nutrient content is both spatially and temporally dynamic (Lenhart et al., 2015; Deans et al., 2016, 2018), insect herbivores are exposed to an incredible amount of nutritional variability. This variability can constrain insects to feeding on sub-optimal resources, but it can also provide an opportunity for insects to regulate their intake of specific nutrients to obtain an optimal balance. Nutrient regulation has implications for pest control strategies in agricultural systems, as the nutritional state of pest species may impact their susceptibility to insecticides. Deans et al. (2017) showed that diet macronutrient balance has significant effects on the susceptibility of Helicoverpa zea larvae to Cry1Ac, an endotoxin expressed in transgenic Bt crops. This was demonstrated using a highly inbred laboratory strain of H. zea, limiting the applicability of these results to field populations that encompass greater genetic diversity. In this study, we assessed the impact of field-relevant macronutrient variability on the efficacy of two Bt endotoxins, Cry1Ab and Cry1Ac, using three field populations collected from different geographic regions. This was done to further understand the impact of nutritional variability on Bt susceptibility and also to determine the relevance of these effects in the field. While we saw limited differences in Cry susceptibility across populations, dietary effects were highly variable. Across populations there were distinct population-level differences in the interactions between Cry concentration and diet, the type of Cry toxin impacted by diet, and the treatment diet that produced optimal survival and performance. These results show that nutrition can have strong impacts on Bt susceptibility but also that these impacts are strongly affected by genetic background in H. zea. To accurately assess Bt susceptibility in the field, including resistance monitoring, bioassay methods should incorporate the appropriate nutritional parameters and be as localized as possible.

scholarly journals Moving towards a reliable HIV incidence test – current status, resources available, future directions and challenges ahead

2016 ◽  
Vol 145 (5) ◽  
pp. 925-941 ◽  
Author(s):  
G. MURPHY ◽  
C. D. PILCHER ◽  
S. M. KEATING ◽  
R. KASSANJEE ◽  
S. N. FACENTE ◽  
...  
Keyword(s):  
Performance Metrics ◽  
Critical Path ◽  
Population Level ◽  
Current Status ◽  
Hiv Incidence ◽  
Recent Infection ◽  
Novel Approach ◽  
Product Profile ◽  
And Performance ◽  
The Impact

SUMMARYIn 2011 the Incidence Assay Critical Path Working Group reviewed the current state of HIV incidence assays and helped to determine a critical path to the introduction of an HIV incidence assay. At that time the Consortium for Evaluation and Performance of HIV Incidence Assays (CEPHIA) was formed to spur progress and raise standards among assay developers, scientists and laboratories involved in HIV incidence measurement and to structure and conduct a direct independent comparative evaluation of the performance of 10 existing HIV incidence assays, to be considered singly and in combinations as recent infection test algorithms. In this paper we report on a new framework for HIV incidence assay evaluation that has emerged from this effort over the past 5 years, which includes a preliminary target product profile for an incidence assay, a consensus around key performance metrics along with analytical tools and deployment of a standardized approach for incidence assay evaluation. The specimen panels for this evaluation have been collected in large volumes, characterized using a novel approach for infection dating rules and assembled into panels designed to assess the impact of important sources of measurement error with incidence assays such as viral subtype, elite host control of viraemia and antiretroviral treatment. We present the specific rationale for several of these innovations, and discuss important resources for assay developers and researchers that have recently become available. Finally, we summarize the key remaining steps on the path to development and implementation of reliable assays for monitoring HIV incidence at a population level.

Introduction to pertussis transmission and epidemiological dynamics

Pertussis ◽  
2018 ◽  
pp. 6-25
Author(s):  
Pejman Rohani ◽  
Samuel V. Scarpino
Keyword(s):  
Control Strategies ◽  
Age Distribution ◽  
Population Level ◽  
Vaccine Uptake ◽  
Effective Control ◽  
Transmission Potential ◽  
Epidemic Period ◽  
The Impact ◽  
Pertussis Epidemiology

Resolving the long-term, population-level consequences of changes in pertussis epidemiology, arising from bacterial evolution, shifts in vaccine-induced immunity, or changes in surveillance, are key challenges for devising effective control strategies. This chapter reviews some of the key features of pertussis epidemiology, together with the underlying epidemiological principles that set the context for their interpretation. These include the relationship between the age distribution of cases and pertussis transmission potential, the impact of vaccine uptake on incidence, periodicity and age incidence, as well as spatially explicit recurrent pertussis epidemics and associated extinction frequency. This review highlights some of the predictable and consistent aspects of pertussis epidemiology (e.g. the systematic increase in the inter-epidemic period with the introduction of whole-cell vaccines) and a number of important heterogeneities, including variations in contemporary patterns of incidence and geographic spread.

364 Blood Profile of Kiko Does Raised on Grass-legume-mixed Pastures vs. Sole-grass Pastures During Fall

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 202-202
Author(s):  
Anand Tiwari ◽  
Uma Karki ◽  
Kendra Norwood ◽  
Ja’Nia Johnson ◽  
Lila B Karki
Keyword(s):  
Soil Health ◽  
Live Weight ◽  
Nutrient Content ◽  
Perennial Grasses ◽  
Animal Performance ◽  
Blood Profile ◽  
Group 2 ◽  
And Performance ◽  
The Impact ◽  
Group 1

Abstract Goats raised in pastures dominated with perennial grasses in the southeast United States commonly show poor health and performance. Addition of legumes to grass pastures may improve nutrient content and enhance animal performance. However, how legume addition to pastures would impact blood profile in goats has not been documented well. The objective of the study was to evaluate the impact of legume-grass mixed pastures on the blood profile of Kiko does. The study was conducted in fall 2020 using 10 fenced plots (average plot size: 0.44 ha). Five plots were sown to southern peas (Vigna unguiculata (L.) Walp.)-browntop millet (Urochloa ramosa L. Nguyen) 50:50 mix) and remaining five plots to sole browntop millet. Nineteen Kiko does (initial age 15–16 months and live weight - 34 ± 1.4 kg) were divided into two uniform groups: Group 1 and Group 2. Does in Group 1 were allocated to legume-grass plots and Group 2 to sole grass plots; they were rotationally stocked in their respective plots for 87 days. Blood samples were collected on Day 1 before allowing them to their respective plots, Day 47, and Day 87. Samples were analyzed for different cellular and metabolic parameters. GLM procedure in SAS 9.4. was used to analyze the data. Group-1 does had higher level of basophil, glucose, and blood urea nitrogen, but lower level of globulin concentration was significantly higher in compared to Group 2 (P < 0.05). Interaction effect of group and sampling date occurred for 21 variables (P < 0.05). Results indicated that addition of legume forage in pastures can alter blood profile of grazing goats. Further investigation on the impact of mixing legumes with grass pastures on animal performance, economics, and soil health will be helpful to understand the holistic effect of legumes on animal agriculture.

scholarly journals Fault-Tolerant Control Strategies and Capability without Redundant Sub-Modules in Modular Multilevel Converters

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1726 ◽  
Author(s):  
Jinke Li ◽  
Jingyuan Yin
Keyword(s):  
Fault Tolerant ◽  
Control Strategies ◽  
Fault Tolerant Control ◽  
Mathematics Model ◽  
Multilevel Converters ◽  
Modular Multilevel Converters ◽  
Voltage Balance ◽  
And Performance ◽  
Level Converter ◽  
The Impact

Sub-module (SM) faults in modular multilevel converters (MMCs) without redundancies result in unbalanced converter output voltages and improper control of modulation due to an unequal number of SMs inserted between the different phase-legs. The derived mathematics model of the MMC demonstrates the impact of the SM fault in the circulating currents and capacitor voltages. For achieving the SM fault-tolerance, detailed analysis of the MMC’s electrical quantities under SM fault-tolerant algorithms is provided together with two modulation reconfiguration techniques for maintaining voltage balance. Fault-tolerant abilities of the two modulation algorithms are also discussed and defined. Simulation results from a 21-level converter and experimental work in a three-phase five-level converter demonstrate the feasibility and performance of the proposed fault-tolerant control strategies.

scholarly journals A multi-scale epidemic model of Salmonella infection with heterogeneous shedding

2020 ◽  
Vol 67 ◽  
pp. 261-284
Author(s):  
Simon Labarthe ◽  
Béatrice Laroche ◽  
Thi Nhu Tao Nguyen ◽  
Bastien Polizzi ◽  
Florian Patout ◽  
...  
Keyword(s):  
Control Strategies ◽  
Food Poisoning ◽  
Population Level ◽  
Pathogen Transmission ◽  
Modeling Framework ◽  
Multi Scale ◽  
Multiscale Modeling Framework ◽  
The Individual ◽  
Random Fluctuations ◽  
The Impact

Salmonella strains colonize the digestive tract of farm livestock, such as chickens or pigs, without affecting them, and potentially infect food products, representing a threat for human health ranging from food poisoning to typhoid fever. It has been shown that the ability to excrete the pathogen in the environment and contaminate other animals is variable. This heterogeneity in pathogen carriage and shedding results from interactions between the host’s immune response, the pathogen and the commensal intestinal microbiota. In this paper we propose a novel generic multiscale modeling framework of heterogeneous pathogen transmission in an animal population. At the intra-host level, the model describes the interaction between the commensal microbiota, the pathogen and the inflammatory response. Random fluctuations in the ecological dynamics of the individual microbiota and transmission at between-host scale are added to obtain a drift-diffusion PDE model of the pathogen distribution at the population level. The model is further extended to represent transmission between several populations. The asymptotic behavior as well as the impact of control strategies including cleaning and antimicrobial administration are investigated through numerical simulation.

scholarly journals Exogenous re-infection and the dynamics of tuberculosis epidemics: local effects in a network model of transmission

2006 ◽  
Vol 4 (14) ◽  
pp. 523-531 ◽  
Author(s):  
Ted Cohen ◽  
Caroline Colijn ◽  
Bryson Finklea ◽  
Megan Murray
Keyword(s):  
Network Model ◽  
Disease Transmission ◽  
Control Strategies ◽  
Disease Incidence ◽  
Infected Individual ◽  
Population Level ◽  
Recent Infection ◽  
Tb Control ◽  
Relative Contribution ◽  
The Impact

Infection with Mycobacterium tuberculosis leads to tuberculosis (TB) disease by one of the three possible routes: primary progression after a recent infection; re-activation of a latent infection; or exogenous re-infection of a previously infected individual. Recent studies show that optimal TB control strategies may vary depending on the predominant route to disease in a specific population. It is therefore important for public health policy makers to understand the relative frequency of each type of TB within specific epidemiological scenarios. Although molecular epidemiologic tools have been used to estimate the relative contribution of recent transmission and re-activation to the burden of TB disease, it is not possible to use these techniques to distinguish between primary disease and re-infection on a population level. Current estimates of the contribution of re-infection therefore rely on mathematical models which identify the parameters most consistent with epidemiological data; these studies find that exogenous re-infection is important only when TB incidence is high. A basic assumption of these models is that people in a population are all equally likely to come into contact with an infectious case. However, theoretical studies demonstrate that the social and spatial structure can strongly influence the dynamics of infectious disease transmission. Here, we use a network model of TB transmission to evaluate the impact of non-homogeneous mixing on the relative contribution of re-infection over realistic epidemic trajectories. In contrast to the findings of previous models, our results suggest that re-infection may be important in communities where the average disease incidence is moderate or low as the force of infection can be unevenly distributed in the population. These results have important implications for the development of TB control strategies.

scholarly journals Pest suppression by ant biodiversity is modified by pest biodiversity

2015 ◽  
Author(s):  
David J Gonthier ◽  
Ryan Kuesel ◽  
Ivette Perfecto
Keyword(s):  
Control Strategies ◽  
Pest Species ◽  
Predator Species ◽  
Control Programs ◽  
Pest Damage ◽  
Multiple Predator Species ◽  
Pest Suppression ◽  
Food Web Complexity ◽  
The Impact ◽  
Pest Risk

Agroecosystems are often complex ecosystems with diverse food webs. Changes in food web complexity may have important context-dependent consequences for pest control strategies. The success of predator introductions to suppress pests may depend on the diversity of pests. For crops with diverse pest assemblages, it is hypothesized that diverse predator communities are needed to suppress diverse pest assemblages below damaging levels. In this study, we compare the ability of ant predator monocultures and polycultures to suppress single- and diverse- (three species) pest assemblages in a coffee foodweb. We use a factorial experiment that compared treatments of predator and pest diversity to understand the impact of pest diversity on multiple predator effects. We show that predator polycultures enhanced pest risk relative to predator monocultures significantly more in the diverse-pest treatment relative to in the single-pest treatments for two of three pest species. Further, we show that pest diversity significantly reduced pest risk in all predator treatments except for the predator polyculture treatment. These results suggest that pest diversity may reduce the efficiency of single predator species at suppressing pest damage, but do not limit multiple predator species. This in turn leads to stronger effects of predator diversity with greater pest diversity. These results highlight the need to consider foodweb complexity, such as pest diversity, when designing and implementing biology control programs.

scholarly journals Introduction to the Cancer Intervention and Surveillance Modeling Network (CISNET) Breast Cancer Models

2018 ◽  
Vol 38 (1_suppl) ◽  
pp. 3S-8S ◽  
Author(s):  
Oguzhan Alagoz ◽  
Donald A. Berry ◽  
Harry J. de Koning ◽  
Eric J. Feuer ◽  
Sandra J. Lee ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Control Strategies ◽  
Cancer Control ◽  
Population Level ◽  
Breast Cancer Outcomes ◽  
Detection Technology ◽  
Cancer Models ◽  
Incidence And Mortality ◽  
Cancer Intervention ◽  
The Impact

The Cancer Intervention and Surveillance Modeling Network (CISNET) Breast Cancer Working Group is a consortium of National Cancer Institute–sponsored investigators who use statistical and simulation modeling to evaluate the impact of cancer control interventions on long-term population-level breast cancer outcomes such as incidence and mortality and to determine the impact of different breast cancer control strategies. The CISNET breast cancer models have been continuously funded since 2000. The models have gone through several updates since their inception to reflect advances in the understanding of the molecular basis of breast cancer, changes in the prevalence of common risk factors, and improvements in therapy and early detection technology. This article provides an overview and history of the CISNET breast cancer models, provides an overview of the major changes in the model inputs over time, and presents examples for how CISNET breast cancer models have been used for policy evaluation.

scholarly journals Pest suppression by ant biodiversity is modified by pest biodiversity

2015 ◽  
Author(s):  
David J Gonthier ◽  
Ryan Kuesel ◽  
Ivette Perfecto
Keyword(s):  
Control Strategies ◽  
Pest Species ◽  
Predator Species ◽  
Control Programs ◽  
Pest Damage ◽  
Multiple Predator Species ◽  
Pest Suppression ◽  
Food Web Complexity ◽  
The Impact ◽  
Pest Risk

Agroecosystems are often complex ecosystems with diverse food webs. Changes in food web complexity may have important context-dependent consequences for pest control strategies. The success of predator introductions to suppress pests may depend on the diversity of pests. For crops with diverse pest assemblages, it is hypothesized that diverse predator communities are needed to suppress diverse pest assemblages below damaging levels. In this study, we compare the ability of ant predator monocultures and polycultures to suppress single- and diverse- (three species) pest assemblages in a coffee foodweb. We use a factorial experiment that compared treatments of predator and pest diversity to understand the impact of pest diversity on multiple predator effects. We show that predator polycultures enhanced pest risk relative to predator monocultures significantly more in the diverse-pest treatment relative to in the single-pest treatments for two of three pest species. Further, we show that pest diversity significantly reduced pest risk in all predator treatments except for the predator polyculture treatment. These results suggest that pest diversity may reduce the efficiency of single predator species at suppressing pest damage, but do not limit multiple predator species. This in turn leads to stronger effects of predator diversity with greater pest diversity. These results highlight the need to consider foodweb complexity, such as pest diversity, when designing and implementing biology control programs.

scholarly journals Genome evolution in an agricultural pest following adoption of transgenic crops

2020 ◽  
Author(s):  
Megan L. Fritz ◽  
Kelly A. Hamby ◽  
Katherine Taylor ◽  
Alexandra M. DeYonke ◽  
Fred Gould
Keyword(s):  
Helicoverpa Zea ◽  
Agricultural Practices ◽  
Holistic Approach ◽  
Transgenic Crops ◽  
Pest Species ◽  
Whole Genome Analysis ◽  
Genomic Change ◽  
Cry Toxin ◽  
Polygenic Selection ◽  
Broad Understanding

AbstractReplacement of synthetic insecticides with transgenic crops for pest management has been both economically and environmentally beneficial. These benefits have often eroded as pests evolved resistance to the transgenic crops, but a broad understanding of the timing and complexity of the adaptive changes which lead to field-evolved resistance in pest species is lacking. Wild populations of Helicoverpa zea, a major lepidopteran crop pest and the target of transgenic Cry toxin-expressing cotton and corn, have recently evolved widespread, damaging levels of resistance. Here, we quantified patterns of genomic change in wild H. zea collected between 2002 and 2017 when adoption rates of Cry-expressing crops expanded in North America. Using a combination of genomic and genotypic approaches, we identified significant temporal changes in allele frequency throughout the genomes of field-collected H. zea. Many of these changes occurred concurrently with increasingly damaging levels of resistance to Cry toxins between 2012 and 2016, in a pattern consistent with polygenic selection. Surprisingly, none of the eleven previously described Cry resistance genes showed signatures of selection in wild H. zea. Furthermore, we observed evidence of a very strong selective sweep in one region of the H. zea genome, yet this strongest change was not additively associated with Cry resistance. This first, whole genome analysis of field-collected specimens to study evolution of Cry resistance demonstrates the potential and need for a more holistic approach to examining pest adaptation to changing agricultural practices.

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