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<p>The goal of this project is to evaluate the effects of distance and a complex breeding system as potential barriers to gene flow among populations of onion thrips, to monitor seasonal changes of population structure, and to characterize the changes in presence and abundance of an insecticide resistance trait over time in relation to the metapopulation structure of onion thrips populations as determined using molecular markers. Specific objectives are: </p>
<p>1. Characterize species and population level differences that are due to complex reproductive biology and determine whether reproductive mode is a barrier to gene flow; </p>
<p>2. Characterize the seasonal and yearly changes in genetic variation within and among onion onion thrips populations; and </p>
<p>3. Characterize the seasonal and yearly abundance and distribution of pyrethroid insecticide resistance in onion thrips populations. </p>
<p>The resulting knowledge of metapopulation structure and gene flow among onion thrips populations as determined by distance and habitat will provide an informed basis for determining the scale over insecticide resistance management plans can be optimally applied to enhance efficacy and sustainability. Results will also inform future studies of thrips-transmitted plant viruses, insect metapopulation structure, population genetics, the spread and persistence of economically important traits in population, and host-plant related population structure.</p>
<p>NON-TECHNICAL SUMMARY:<br/> Onion thrips feeding damages many vegetable and field crops. They also spread two tospoviruses, Iris yellow spot virus and Tomato spotted wilt virus, which cause over $1 billion in crop losses annually worldwide. Management of onion thrips populations and the plant viruses they spread is of increasing concern due to the development of insecticide resistant populations, and the limited progress that has been made towards decreasing losses due to epidemics of these viruses. Management is potentially confounded by differences observed among population in insecticide resistance, ability to transmit plant viruses, reproductive biology, and ability to reproduce on different host plants. The presence of genetically distinct groups within a species can significantly impact the design, implementation and effectiveness of management programs when the
different groups vary in their distribution, propensity to develop insecticide resistant populations, and ability to transmit viruses. One goal of this project is to employ molecular markers to determine if genetic differentiation among onion thrips is due to complex reproductive biology. A second goal is to characterize the effect of spatial isolation on seasonal and yearly changes in genetic variation that exists among and within populations, including changes in the abundance and distribution of genes conditioning resistance to pyrethroid insecticide in onion thrips populations. Ultimately, this project will improve our understanding of the genetic relationships that exist among onion thrips populations. It will provide information about the scale (local or regional) at which insecticide resistance management and tospovirus management plans can be optimally applied to enhance
effectiveness and sustainability. This project addresses the AFRI Challenge area of Food Safety and is aligned with the AFRI Foundation area of Plant health and production and plant products.
<p>APPROACH:<br/> This study will be conducted in the muck soil onion production systems of New York. These are discrete pockets of high organic soil interspersed throughout the NY landscape; separated by a mosaic of urbanization, forests and field crops. These muck soil production systems represent islands of habitat for onion thrips individuals and are essentially closed cropping systems, due to their isolation. Molecular genetic markers (microsatellites and mitochondrial (COI) will be used to investigate whether gene flow occurs among onion onion thrips populations that are parthenogenetic (female only) and those that produce both male and female offspring). They will also be used to determine if populations are genetically differentiated among mucks; if genetic diversity within mucks decreases as the growing season progresses; if genetic diversity over all mucks remains
stable over time; and the amount of genetic differentiation between onion thrips populations is related to the distance separating the populations. Finally, molecular genetic markers for mutations conferring resistance to pyrethroid insecticides will used to investigate the relationship between historic and present use of pyrethriod insecticides in each muck and the frequency of these mutations in the thrips population in those mucks. Findings will be used to inform development of improved systems for managing insecticide resistance and thrips-borne Iris Yellow Spot Virus in New York onion production systems so that they better reflect the levels of genetic isolation among onion thrips populations. Project results and their relevance to thrips management will be disseminated through extension presentations and web-based media. Findings will also be presented in papers or posters
delivered at 2 scientific conferences each year. Satisfactory progress will be ensured through research updates at weekly lab meetings and presentation of results at annual professional meetings as well as the following annual benchmarks: 1. Collect and complete processing of early and late season samples (extract DNA, amplify DNA at all microsatellite and mtDNA COI loci, and sequence mtDNA COI loci)before the end of January in years 1 & 2 year, 2. By April of each year the sodium channel gene for each population will be amplified and sequenced and the data analyzed; 3. Complete a manuscript reporting results for objective 1 by July 1 of year 1. 4. In year two sample samples for the second year of Objectives 2 & 3 will be processed and manuscripts reporting the results will be completed. Research results will be presented at appropriate scientific meetings throughout the course of this
fellowship.
<p>PROGRESS: 2012/08 TO 2013/07<br/>Target Audience: Updates on the results of these studies have been shared with Ed Vargo's, George Kennedy's, and Brian Nault's lab groups at North Carolina State University and Cornell University. Research seminars have also been given at the University of Georgia, the University of Thessaloniki, Greece, and to PIs of the Thrips-Tospovirus CAP Grant. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? This project has provided me the opportunity to work with new lab groups at North Carolina State University, and with researchers at Cornell University. It has also generated collaborations with researchers in Greece, where Thrips tabaci is an economically important pest, and primary vector of TSWV in tobacco production systems. Because of my experience
working with thrips I was selected to participate in a mentoring program that is part of the Thrips-Tospovirus CAP grant. This grant will also be funding my attendance at the Annual Meeting of the Entomological Society of America this year, and will provide opportunities to attend more professional and grower meetings next year (see below). How have the results been disseminated to communities of interest? Updates on the results of these studies have been shared with Ed Vargo, George Kennedy, and Brian Nault lab groups at North Carolina State University and Cornell University. Currently the manuscript for objective 1 is being prepared for publication. What do you plan to do during the next reporting period to accomplish the goals? The microsatellite marker experiments, sequencing of mtCOI, and sequencing of sodium channel markers will be finished this fall. After the experiments have
concluded the data will be analyzed and manuscripts prepared. After all of the analyses have been conducted I will also help to prepare extension materials with Brian Nault for NY onion producers. Next year I plan to give a talk at the NY Empire State EXPO, and if possible, a departmental seminar at Cornell. In addition, I am scheduled to give a departmental seminar at U.C. Davis, and plan to attend the International Thrips-Tospovirus Meeting to disseminate the results of my studies.