Progress 10/01/10 to 09/30/13
Outputs
Target Audience: Our target audience was other academic researchers. Changes/Problems: One change that we made was to reserve some of the funding that was originally allocated to genotyping using micorsatellites to next-generation sequencing. We were trying to collect some preliminary data to support additional grants that will be submitted to federal agencies. What opportunities for training and professional development has the project provided? I have trained two graduate students under this grant. Dr. Victor Izzo (Ph. D. awarded Dec. 2013) was the main student supported under the grant. Also, research funding for Tara Madsen-Steigmeyer was supported using this project. How have the results been disseminated to communities of interest? We have made multiple presentations and have submitted and published four peer-reviewed publications from this work. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Characterize how geographic populations (ancestral Mexican and derived US) vary in their ability to tolerate cold climates. Ancestral and derived populations did not express different physiological responses (i.e. SCPs) to freezing temperatures. However, ancestral and derived populations responded differently to the onset of winter conditions and displayed dissimilar overwintering behaviors. The majority of ancestral beetles failed to initiate diapause and dug upward within experimental mesocosms. Differences in overwintering behavior also resulted in significant variation in overwintering success as derived populations displayed higher overwintering survivorship when compared with ancestral populations. Characterize how geographic populations vary in their ability to feed on their natal plant, Solanum rostratum and potato, Solanum tuberosum Vermont pest populations displayed a distinctly expanded diet breadth when compared with non-pest derived (Kansas) and ancestral (Texcoco, Morelos and Oaxaca) populations. They also failed to distinguish between cultivated and wild host plants during the feeding choice experiment. Vermont beetles accepted and grew at an equal or higher rate when compared with all other beetles on all host species. Finally, Vermont beetles exhibited a higher growth rate on leaf samples, as opposed to flowers, when compared with all other populations. The greater preference, acceptance, and performance of Vermont beetles on all host species and plant structures underscores the virulence of the pest form of the beetle Population genetic structure and phylogeographic structure of beetle populations. We have mtDNA and microsatellite (6 loci) data for US and Mexican populations. US pest populations appear to be highly admixed, but do not appear directly descended from Mexican populations. Among the Mexican populations, a phylogeographic analysis using Nei’s neighboring-joining (FST) found that beetles from Texcoco, Mexico are the most highly related to US beetle populations. Determine if potato plants may induce the likelihood of beetle diapause. Potato plants grown under short day conditions displayed significantly higher levels of leaf nitrogen compared with long day treated plants. Over 65% of beetles feeding upon short-day treated plants initiated diapause compared with < 20% of beetles placed upon long-day treated plants.
Publications
- Type:
Journal Articles
Status:
Awaiting Publication
Year Published:
2014
Citation:
Izzo, V. and Y. H. Chen. Published online. Time of the Season: Effect of photoperiodism on host-mediated cues for diapause induction in Leptinotarsa decemlineata. Ecological Entomology.
Izzo, V.*, J. Armstrong^, D. J. Hawthorne, Y. H. Chen. Published online. Geographic variation in winter hardiness of a common agricultural pest, Leptinotarsa decemlineata, The Colorado potato beetle. Evolutionary Ecology
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Progress 10/01/11 to 09/30/12
Outputs
OUTPUTS: Significant accomplishments and outputs that contribute to project goals and objectives We have found that there is geographic variation among beetle populations in their ability to survive northern winters. We collected beetles from several Mexican states (Jalisco, Oaxaca, Texcoco), Kansas, and Vermont. After the beetles experience the shortening days during fall, we buried them in PVC tubes at 15 cm below the surface. The Vermont population showed the highest survival followed by the Kansas populations. The Mexican populations varied in their ability to survive temperate overwintering conditions. About 6% of beetles from Texcoco survived the Vermont winter, but no beetles from any other populations survived. We are currently finishing the remainder of the microsatellite study and a phylogeographic study. We have collected some additional populations from Texas and the Midwest that should provide greater resolution for our phylogeography study. The research will be presented at a program symposium at the Annual Meeting of the Entomological Society of America in Knoxville, TN, Nov. 11-15. We are also currently preparing several manuscripts for this work. In the final year of the study, we plan to conduct a RAD-tag sequencing project that will provide much more information on the origin of the pest forms of CPB. We have already made a RAD-tag library, and will be sequencing them on a Illumina Hi-Seq at University of Delaware in the next month. One of the most interesting findings is to see that there is geographic variation among beetle populations in ecophysiological traits. This means that beetles may have undergone significant evolutionary change in order to adapt to northern climatic conditions. However, one recent finding that has yet to be substantiated further through study is that there appears to be variation among Mexican populations for cold tolerance. PARTICIPANTS: 1)Yolanda Chen (PD) 2) This grant has provided significant training opportunities for several students. Victor Izzo - Ph. D. student Tara Madsen-Steigmeyer - Ph. D. student Joe Labrum - B. S. in Biology Jordan Armstrong - B. S. in Biology Jack Boyajian - B. S. in Biology TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
We have found that pest beetles appear to be most similar in feeding performance and cold tolerance to beetles from Texcoco, Mexico. Therefore, it is possible that beetles from the Mexican highlands were the ancestors of the modern pests. We have some preliminary genetic data that suggests that the Texcoco populations are also the most genetically similar to pest CPB populations. CPB is a widespread global pest, found throughout the Northern Hemisphere. However, there is still a great deal of mystery around its origins, and how its origins contribute to its extreme success. Through our study, we believe we are better able to inform whether pre-existing variation or rapid evolution underlied the beetles. We anticipate that our results will help to provide greater understanding on the extreme success of CPB as a pest of potatoes globally. The beetle is highly unusual in that it originates from the subtropical highlands, and is now invading into the Arctic Circle. We anticipate that understanding the ecological and evolutionary forces that have promoted its success will help us to better understand how novel technologies can be used to control it. By developing alternative non-insecticidal means of controlling this highly invasive pest, we hope that our research will benefit potato farmers within the northern hemisphere. Stakeholders (farmers, research specialists, IPM practitioners) need assistance because this is one of the oldest and notoriously damaging pests. Attempts to control the beetle started the pesticide industry. Yet, the beetle has been enormously successful in evolving resistance to all the major pesticide chemistries. In order to develop lasting sustainable solutions, it is important to understand the nature of the beetles success in northern potato agroecosystems, and develop strategies to undermine that success.
Publications
- Alyokhin, A. A., Y. H. Chen, M. Udalov, G. Benkovskaya, and L. Lindstrom. 2012. Evolutionary considerations in potato pest management. In P. Giordanengo, C. Vincent, and A. A. Alyokhin, Insect pests of potato: biology and management. Academic Press. Waltham, MA, USA.
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Progress 10/01/10 to 09/30/11
Outputs
OUTPUTS: Hatch progress report The overall goal of this proposal is to examine how climatic and biotic factors have influenced the geographic range expansion of Colorado potato beetle (CPB), and to forecast how climate change may influence the abundance and distribution of beetle populations in the future. In Objective 1, we are examining beetle population genetic structure and the extent of gene flow throughout the US and Mexico. We have sampled CPB populations from 6 states within Mexico (Jalisco, Morelos, Texcoco, Tlaxcala, Guerrero, Queretaro, Puebla), and from seven US states (WI, MA , KS, MD, VT, VA and ME). We have optimized 8 microsatellite loci, and have begun genotyping our samples. We are also sequencing CPB mtDNA and other nuclear markers, in order to determine the relationship between ancestral and derived pest populations. Objective 2 is focused on how natal climatic conditions affect the ability of beetle populations to respond to novel climatic conditions. We are using 3 Mexican and 2 US beetle populations to assess their overwintering capability in Vermont. We induced beetles to diapause or hibernate in the lab prior to placing them in mesocosms, but this resulted in higher mortality in the field. Prompted by the very high level of mortality last year, we have revised our diapause induction protocol and are rearing them on plants outside, where they can be exposed to ambient light and climatic conditions. Diapausing beetles will be secured in soil mesocosms and inserted below ground in field margins and field areas at the UVM Horticultural Research Farm. The mesocosms will be extracted in the spring of 2012 to assess overwintering survivorship. In Objective 3, we are examining how geographic origin affects beetle ecophysiological adaptations to temperate climates. We now have complete data on supercooling points from five different beetle populations. Supercooling points are physiological indicators of beetle cold tolerance. We will disseminate the results to other entomologists through scholarly publications and presentations at national meetings. PARTICIPANTS: - An undergraduate research project is currently being performed by Joe Labrum (Biology Major). His study, a phylogeographic study between ancestral and derived pest populations, will work in concert with our microsatellite analysis to help resolve the historical genetic aspects of the range expansion of L. decemlineata. - Another undergraduate Biology student, Jordan Armstrong, is studying CPB geographic variation in ovipositional ability on natal and non-natal hosts. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
One of the most interesting findings for us is to see that there is geographic variation among beetle populations in ecophysiological traits. This means that beetles may have undergone significant evolutionary change in order to adapt to northern climatic conditions. However, one recent finding that has yet to be substantiated further through study is that there appears to be variation among Mexican populations for cold tolerance. Given that we are in year 2 of this award, we anticipate that our results will help to provide greater understanding on the extreme success of CPB as a pest of potatoes globally. The beetle is highly unusual in that it originates from the subtropical highlands, and is now invading into the Arctic Circle. We anticipate that understanding the ecological and evolutionary forces that have promoted its success will help us to better understand how novel technologies can be used to control it. By developing alternative non-insecticidal means of controlling this highly invasive pest, we hope that our research will benefit potato farmers within the northern hemisphere. Stakeholders (farmers, research specialists, IPM practitioners) need assistance because this is one of the oldest and notoriously damaging pests. Attempts to control the beetle started the pesticide industry. Yet, the beetle has been enormously successful in evolving resistance to all the major pesticide chemistries. In order to develop lasting sustainable solutions, it is really important to understand the nature of the beetles success in northern potato agroecosystems, and develop strategies to undermine that success.Given that we are in year 2 of this award, we anticipate that our results will help to provide greater understanding on the extreme success of CPB as a pest of potatoes globally. The beetle is highly unusual in that it originates from the subtropical highlands, and is now invading into the Arctic Circle. We anticipate that understanding the ecological and evolutionary forces that have promoted its success will help us to better understand how novel technologies can be used to control it. By developing alternative non-insecticidal means of controlling this highly invasive pest, we hope that our research will benefit potato farmers within the northern hemisphere. Stakeholders (farmers, research specialists, IPM practitioners) need assistance because this is one of the oldest and notoriously damaging pests. Attempts to control the beetle started the pesticide industry. Yet, the beetle has been enormously successful in evolving resistance to all the major pesticide chemistries. In order to develop lasting sustainable solutions, it is really important to understand the nature of the beetles success in northern potato agroecosystems, and develop strategies to undermine that success.
Publications
- No publications reported this period
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