Progress 08/01/12 to 07/31/15
Outputs
Target Audience:Through this project, we reached a target audience of several different types of scientific professionals, growers, crop consultants, industry representatives and members of the general public. We reached other researchers and extension personnel interested in sustainable pest management, including entomologists as well as agronomists and weed scientists. We also reached members of the public, and primarily students in grades 3-6 interested in entomology, agricultural pests, and plant-insect interactions. We believe our work investigating the influence of plant diversity on plant and insect communities will be useful to scientists working in both basic and applied settings on plants and animals and the ecological consequences of diversity. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?This project has provided many opportunities for professional development. The project provided support for attendance and presenting at both branch and national meetings of the Entomological Society of America and participation at these meetings and participation on professional society committees, which included organizing symposia and workshops. The project has also provided opportunities to present the research at a university-sponsored field day and at university-wide research exhibitions at Penn State and at a field day. The project also provided training in phytohormone analysis. How have the results been disseminated to communities of interest?We have disseminated research from this project to various communities of interest through several types of presentations, and have reached a diverse audience. This includes other entomologists, ecologists, crop consultants, extension personnel, growers, and members of the public. Research from the project was presented at both branch and national meetings of the Entomological Society of America. In addition, three separate poster presentations on this project were given at research exhibitions at Penn State that spanned from very specialized to very broad and as a departmental seminar at Penn State. This research was used several times as the basis for hands on investigations conducted by elementary school students during entomology-themed summer camps. The experiment helped promote interest in entomology, sustainable pest management, and biological control and taught students how to test hypotheses through experimentation. Furthermore, sustainable pest management and the study organisms were woven throughout many local outreach events. A manuscript based on work from this project has been submitted to Functional Ecology. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
The overall goal of this project was to examine the pest management and crop production benefits of increasing in-field crop genotypic diversity by growing mixtures of varieties in place of single-variety monocultures. Our goal was to investigate the potential of higher levels of crop genotypic diversity to help ameliorate the abiotic (drought) and biotic (aphid) stressors that climate change will bring to crop fields. Mixtures of varieties could provide an easily adoptable and sustainable tactic for managing these stressors. We first conducted a variety trial to select varieties and screened a large pool of variety for their independent resistances to drought and aphids. This allowed us to manipulate diversity for the traits of interest. A greenhouse experiment aimed to examine the influence of plant genotypic diversity at the small pot scale, allowing aphid movement between plants. We were not able to properly test the original hypotheses that variety mixtures would reduce aphid populations and would do so most strongly when plants were drought stressed because of an interaction between morph determination and fertilization/plant nutrient stress. The conditions were fairly unnatural and specific to this experiment, but this resulted in spikes in aphid populations after two weeks on those mixtures that contained the most resistant variety. The mixtures that did not contain this variety were not different than the monocultures for aphid populations. More importantly, we conducted two years of work for addressing objective 1 and examining how the genotypic diversity of a plant's neighborhood affects its resistance to herbivores and if any effect is more pronounced in the presence of drought. We determined that when taken across all five of the varieties we tested, the plant-plant interactions in more diverse neighborhoods generated associational resistance and reduced aphid performance. Contrary to our predictions, the effect was greatest when plants were adequately watered and was minimal when plants had been drought stressed. Plant aboveground biomass was slightly reduced in mixtures and under both watering treatments, suggesting a cost of resistance to aphids, although we did not allow for feedback from damaging levels of aphids. In addition, we worked to identify mechanisms that would help explain the effects of diversity we saw on aphid performance. Our analysis of defense-related phytohormones levels (salicylic acid), did not reveal an explanatory role of plant defenses for the effects of diversity on aphid performance, although more extensive analyses of plant defenses across multiple time points may still have determined plant defenses were important. We did find that neighborhood diversity influenced the size of the mother aphid at adulthood, partially explaining the influence of diversity. These results suggest that interactions between varieties in mixtures of varieties can affect herbivore performance even when herbivores do not move between plants and that abiotic (drought) stress may minimize the strength of the effect. Variety mixtures appear to hold promise for the management of insect pests and crop genotypic diversity can influence herbivores via associational resistance. However, our results also suggest individual varieties react differently to growing in mixtures. These findings contribute to a growing body work from both agricultural and natural systems demonstrating the ecological significance of plant genotypic diversity. Throughout the project, we disseminated results from the project to our target audience of other scientists, extension personnel and, local growers and incorporated this research into K-12 educational outreach activities.
Publications
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2015
Citation:
Grettenber, I.M. 2015. The influence of increased crop genotypic diversity on arthropods in agroecosystems (Doctoral dissertation). Retrieved from Penn State Electronic Theses and Dissertations.
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Progress 08/01/13 to 07/31/14
Outputs
Target Audience: We reached a target audience consisting of several different types of scientific professionals, growers, crop consultants, industry representatives and members of the general public. We reached other researchers and extension personnel interested in sustainable pest management, which included entomologists as well as agronomists and weed scientists. In addition, we reached members of the public, primarily students in grades 3-6 interested in entomology, which includes plant-insect interactions. We believe our work investigating the influence of plant diversity on plant and insect communities will be useful to plant and insect scientists working in basic and applied settings. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? The project has provided opportunities for professional development through attendance and presentations at Entomological Society of America meetings, as well as participation on professional society committees. This projected has also provided opportunities to present at university-wide research exhibitions at Penn State and at a field day. How have the results been disseminated to communities of interest? During the last reporting period, research from this project has been disseminated to communities of interest through several types of presentations, which reached a diverse audience. This includes other entomologists, ecologists, crop consultants, extension personnel, growers ,and members of the public.This research was presented at both the branch and national meetings of the Entomological Society of America. In addition, three poster presentations on this project were given at research exhibitions at Penn State that spanned from very specialized to very broad. This research was again used as the basis for a hands on investigation conducted by elementary school students during an entomology-themed summer camp. The experiment helped promote interest in entomology, sustainable pest management, and biological control and taught students how to test hypotheses through experimentation. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
This project aims to investigate the pest management and crop production benefits of planting fields with mixtures of varieties rather than monocultures of a single variety (and therefore increasing crop genotypic diversity). Our goal is to explore the potential of crop genotypic diversity to simultaneously manage the abiotic and biotic stressors that will confront crop fields under a changing climate. Variety mixtures could provide an easily adoptable and sustainable tactic for managing these stressors. To begin the project and facilitate all objectives, a variety trial was initially completed to screen varieties for aphid and drought resistance/susceptibility and to identify varieties to be used for all subsequent experiments. Activities for objective one have been focused on the influence of genotypic diversity (and therefore relatedness of a plant’s neighbors) on plant productivity and stress resistance at the individual plant level. Promising results from objective one have led us to pursue this line of questioning with further greenhouse experiments instead of examining the influence of cultivar mixtures in the field, which would have come with greater risk. This will increase the scope of the promising results and will elucidate the mechanism at work. These experiments have nearly been completed, although sample analysis and data analysis are ongoing. Greenhouse experiments for objective two that examine the influence of plant genotypic diversity at the small pot scale, allowing aphid movement between plants, have been completed, and data analysis is ongoing. Up to this point, results are promising and indicate that crop genotypic diversity may help mange resistance to aphids, including under drought stress. However, diversity per se may not be effective and effective crop management strategies may need to incorporate specific varieties into mixtures. This research has been shared during the last reporting period through a number of outlets, including presentations at professional society conferences, multiple university research exhibitions, field days, and in K-12 outreach activities.
Publications
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Progress 08/01/12 to 07/31/13
Outputs
Target Audience: The target audiences reached during this reporting period primarily consists of other researchers and entomologists, including industry representatives, working to identify sustainable pest managment techniques. The target audiences also include extension personnel. Results from this research will also describe the impact of plant diversity on the associated arhtropod community and are therefore broadly useful to pant and insect scientists. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? This project has provided opportunities in professional development through presentations and attendance at Entomological Society of America meetings and at university-wide research exhibitions at Penn State. How have the results been disseminated to communities of interest? Thus far, this research has been disseminated to communities of interest through presentations at Penn State, at other universities, and at professional societies. Presentations have been to diverse audiences that have included researchers within my field, other scientists in unrelated disciplines, and members of the general public. Research for this project was also included in hands-on investigations conducted by elementary-age students as part of an entomology-themed camp. The investigations helped demonstrate to students the ecological principles behind the research and enhanced student understanding and enthusiasm for entomology, pest management and scientific experimentation. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
The overall goal of this project is to elucidate the benefits of increased crop genotypic diversity for managing the simultaneous abiotic and biotic stressors associated with climate change. Research addressing both objectives 1 and 2 are completed or underway. A greenhouse variety trial was run prior to initiation of objectives 1 and 2 to select varieties to include in subsequent experiments. Varieties were screened for their resistance to both drought and aphids. For objective 1, activities are focused on the influence of genotypic diversity in the greenhouse at the individual plant level, especially with respect to effects on pests, and are ongoing. Greenhouse experiments for objective 2 examining the influence of crop genotypic diversity at the scale of a small pot have been largely completed, although a portion of the data still needs to be collected and finalized. Thus far, results are preliminary, but appear to indicate that the effect of crop genotypic diversity on resistance to aphids is context specific and dependent on the specific varieties included in the diverse cultivar mixtures. This research was included in presentations at conferences, university exhibitions and departmental seminars at other institutions. This research was also incorporated into K-12 outreach activities.
Publications
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