Repeated use of field corn (Zea mays L.) hybrids expressing the Cry3Bb1 and mCry3A traits in Nebraska has selected for field-evolved resistance in some western corn rootworm (WCR; Diabrotica virgifera virgifera LeConte) populations. Therefore, this study was conducted to characterize spatial variation in local WCR susceptibility to Cry3Bb1 and mCry3A traits in Keith and Buffalo counties, Nebraska, and determine the relationship between past management practices and current WCR susceptibility. Adult WCR populations were collected from sampling grids during 2015 and 2016 and single-plant larval bioassays conducted with F1 progeny documented significant variation in WCR susceptibility to Cry3Bb1 and mCry3A on different spatial scales in both sampling grids. At the local level, results revealed that neighboring cornfields may support WCR populations with very different susceptibility levels, indicating that gene flow of resistant alleles from high trait survival sites is not inundating large areas. A field history index, comprised of additive and weighted variables including past WCR management tactics and agronomic practices, was developed to quantify relative selection pressure in individual fields. The field history index-Cry3 trait survivorship relationship from year 1 data was highly predictive of year 2 Cry3 trait survivorship when year 2 field history indices were inserted into the year 1 base model. Sensitivity analyses indicated years of trait use and associated selection pressure at the local level were the key drivers of WCR susceptibility to Cry3 traits in this system. Retrospective case histories from this study will inform development of optimal resistance management programs and increase understanding of plant-insect interactions that may occur when transgenic corn is deployed in the landscape. Results from this study also support current recommendations to slow or mitigate the evolution of resistance by using a multi-tactic approach to manage WCR densities in individual fields within an integrated pest management framework.
On‐farm research is a method for transferring technology to farmers, validating small plot research, generating new discovery, and evaluating field‐scale, site‐specific management techniques. Little has been done to understand what motivates farmers to participate in on‐farm research and what the impact of their participation is on their decision making and farm profitability. This study evaluated the University of Nebraska‐Lincoln's over 25 yr‐old on‐farm research program using a semi‐structured, in‐depth interview tool to complete interviews with a stratified sample of 40 of the 140 past‐participants. The focus of this qualitative study was obtaining rich descriptions of farmer participants to better understand motivation for involvement in an on‐farm research program, participant research experiences, and the economic impacts of an on‐farm research program. Quantitative statistical analyses of the qualitative data are included for informational purposes; however, our conclusions focus on the qualitative analysis. Farmers participated in an on‐farm research program for a variety of reasons, most commonly for economic gain. Positive experiences were largely credited to the interactions with university faculty and other farmers. The participating farmers’ perception regarding whether or not the project took too much time was unrelated to whether weigh wagons or yield monitors were used. Farmers were interested in many aspects of research, including project ideation, experimental design, and statistical analysis. Participating farmers’ satisfaction in their experience and implementation of research results was not dependent on the farmers independently generating their research topic. The most impassioned suggestion from the farmer research participants was to develop innovative research projects. Core Ideas In‐depth interviews with participants in an on‐farm research program generated insights into motivation for participation and program impact. Farmers participated in the program for a variety of reasons including economic gain, seeking answers to a specific questions, general curiosity, and a desire for reliable and unbiased research results. Positive experiences in the on‐farm research program were largely credited to interactions with university faculty and other farmers. The origin of the research topic or idea did not influence participant satisfaction in their experience or implementation of the results. Seventy‐five percent of interviewees had put their research results into practice in their farm operation, either by making a change based on results or by not making a change as the research confirmed their current practice.
Group testing is an indispensable tool for laboratories when testing high volumes of clinical specimens for infectious diseases. An important decision that needs to be made prior to implementation is determining what group sizes to use. In best practice, an objective function is chosen and then minimized to determine an optimal set of these group sizes, known as the optimal testing configuration (OTC). There are a few options for objective functions, and they differ based on how the expected number of tests, assay characteristics, and testing constraints are taken into account. These varied options have led to a recent controversy in the literature regarding which of two different objective functions is better. In our paper, we examine these objective functions over a number of realistic situations for infectious disease testing. We show that this controversy may be much ado about nothing because the OTCs and corresponding results (eg, number of tests and accuracy) are largely the same for standard testing algorithms in a wide variety of situations.
A tremendous amount has been written about the library as a learning space and about this model's two most popular outgrowths, the information commons and the learning commons. Little to nothing, however, has been written about how reshaping an academic/research library and repurposing library space affects the library as a collection, its resources, and its collections-related services. This study looks at the immediate impact of opening a learning commons in an academic/research library on circulation, document delivery and interlibrary loan requests for returnables, and on-and off-campus database accesses at one institution.
Patron-driven acquisition has been an important, if contentious, topic for decades, with numerous programs having been piloted, adopted, and reported on, largely favorably, in the library literature. Still, questions and doubts persist for academic libraries, especially where the composition of vendor plans and packages and the judgment of patrons are concerned. Past literature has approached the assessment of patron-driven acquisition by analyzing circulation/usage, comparing peer-library holdings, seeking patrons' or librarians' judgments of utility and suitability, looking for evidence of collection imbalances, and testing for overlap in patrons' and librarians' purchases. To contribute to this literature, this study addresses scholarly impact and examines whose selections-approval plans', librarians', or patrons'-have been most heavily cited. For the social sciences, the sciences, and the humanities, the authors gathered topic-matched random samples of books acquired via approval plans and librarian orders during the first five years of operation of their institutions' interlibrary loan purchase-on-demand patrondriven acquisition program and compared their citation counts to the counts of books acquired via the program. Google Scholar was employed to tally citations.
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