Progress 12/01/14 to 05/31/17
Outputs
Target Audience:Farmers/Gardeners, General Public, Ecological Scientists, Agricultural Scientists Farmers, United States Department of Agriculture, Natural Resources Conservation Service Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?One of the most rewarding aspects of my NIFA fellowship experience was training and mentoring an undergraduate. I hired Katie S. to work with me as a technician in Fall 2015. We were both pleasantly surprised when our employer-employee relationship grew into a mentor-mentee connection. As a mentor, I introduced Katie to UNH's Women in Science organization and helped her prepare for post-undergraduate employment. Through this experience, I improved my abilities to train future scientists, honed my mentoring skills, and, most importantly, helped another woman in science reach her goals. Additional experiences: 1. Guest lectures for Soil Ecology and Agroecology undergraduate courses at UNH. 2. Analyses of crop fungal pathogens. 3. Travel and presentations at multiple conferences including: (a) Tri-Societies of America Conference in Phoenix, AZ -Awarded best student poster for Soil Biology and Biochemistry division (November 2016). (b)UNH Three Minute Thesis competition - Awarded First Place and People's Choice Awards (2016). (c) NIFA Fellow Project Director meeting in Washington, DC (August 2016). (d) Soils Matters Conference organized by NRCS (invited talk, 2017) (e)NOFA-NH Annual Conference (invited talk, 2017) How have the results been disseminated to communities of interest?1. Guest lectures for Soil Ecology and Agroecology undergraduate courses at UNH (2015-2017). 2. Travel and presentation at the 2016 Tri-Societies of America Conference in Phoenix, AZ. Awarded best student poster for Soil Biology and Biochemistry division (November 2016). 4. UNH Three Minute Thesis competition - Awarded First Place and People's Choice Awards (2016). 5. Travel and presentation at the NIFA Fellow Project Director meeting in Washington, DC (August 2016). 6. Invited talks at NRCS organised Soils Matters Conference and the NOFA-NH annual conference (2017). What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
We conducted a greenhouse experiment (May 2016) in which maize seeds pre-coated with an insecticide-fungicide mixture containing neonicotinoids were planted into intact soil food webs collected from sites with a range of PST histories. In this study, we aimed to examine the relative impact the initial introduction of PST has on the soil community compared to successive plantings of treated crops. Maize seeds without PST served as control. We hypothesized soil communities with a history of successive exposures to PST would change very little when seeds with PST were sown, while communities naïve to neonicotinoids would dramatically change in composition with significant decreases in total abundance and diversity upon first exposure to PST. We also measured the incidence of pathogenic fungal root colonization to evaluate if the fungicidal components of the PST varied in effectiveness among soils with different PST histories. Results and Implications The objective of this study was to determine if soil arthropod communities repeatedly exposed to PST with neonicotinoids become less affected, i.e. conditioned, with subsequent exposures to these pesticides. As predicted, our results show that soil communities with histories of seed treatment use were mostly unaffected in their composition, abundance, richness, and diversity within 28-days. In contrast, soil communities naïve to seed treatments significantly change in composition with reductions in total abundance, richness, and diversity within 28-days of their first exposure to seed treatment. These results highlight the dramatic impacts of seed treatments on the soil community the first time it is used in a soil, raising further concerns about increased adoption of this management practice globally (Douglas and Tooker, 2015). Moreover, our results demonstrate that the successive use of seed treatments condition the soil arthropod community such that subsequent exposures only minimally affect community composition. Ecologically, these results suggest the soil community is acclimated to this type of disturbance; however, concerns regarding reduced community composition can lower the community's ability to respond and recover from other types of disturbances (Brussaard et al., 2007), such as predicted increases in the intensity and frequency of climatic events (Hayhoe et al., 2008). In naïve soils, the introduction of PST changed the soil community primarily through the elimination of two to four of the most susceptible (or intolerant) community members. In our soils, Collembolan, especially species in the family Sminthuridae, exhibited the greatest loss in abundance when exposed to PST. These small, oval-bodied hexapods (0.75-3 mm) vary in feeding guilds by species, but most are considered fungivorous contributing to important agroecosystem services like decomposition and nutrient cycling (Triplehorn and Johnson, 2005). Our results suggest highly susceptible non-target community members, such as Collembola Sminthuridae, rapidly succumb (within 28-days) to seed treatments with neonicotinoids resulting in sweeping changes to the composition of the soil arthropod community. Soil arthropod communities with histories of PST exposure exhibited relatively little change with subsequent seed treatment additions which suggests these communities are conditioned to withstand PST disturbances. Disturbance regimes, which includes management practices, selects for organisms tolerant to the disturbance and even favors disturbance specialists, e.g. exotic species (McIntyre and Lavorel, 1994). With respect to seed-applied neonicotinoids, non-insect arthropods like spiders (Araneae) and mites (Acari) are generally more tolerant compared to insects (Douglas and Tooker, 2016). Resistance also becomes an issue with respect to pesticides. Similar to the rise of glyphosate resistant weeds following increased reliance on glyphosate for weed management (NRC, 2010; Powles, 2010), widespread use of neonicotinoids poses a similar risk. To date, neonicotinoids still successfully control many insect species; however, species-level resistance to neonicotinoids currently occurs in a few pest species including aphids, whiteflies, and Colorado potato beetles (Leptinotarsa decemlineata) (Nauen and Denholm, 2005; Bass et al., 2015). The extensive use imposes a growing selection pressure for resistance with the potential to compromise the efficacy of these insecticides (Bass et al., 2015). The fungicides used in PST mixtures often include major site-specific groups such as Quinone outside inhibitors (QoIs; e.g. azoxystrobin) and phenylamides (e.g. mefenoxam). Both of these fungicide groups are at high risk for the emergence of resistance (Fungicide Resistance Action Committee, 2017) because they have site-specific modes of action which means only a single mutation must occur at the target site for a resistant pathogen population to develop (Hahn, 2014). Although mixtures of fungicides and insecticides are readily used in agricultural systems today, our current understanding of their combined effect on the soil fungal community is quite limited, and even more limited when mixed with neonicotinoids. Our study suggests repeatedly using insecticide-fungicide mixtures in a field may reduce the effectiveness of the fungicidal components such that in only one case (among three tested fungal pathogens genera) within 28-days did we observe maize with azoxystrobin, mefenoxam, and thiabendazole fungicide consistently faring better than the untreated control. However, the first-time seed applied fungicides are used their effectiveness appears to depend on the initial composition of the fungal community. For example, the seed treatment completely protected the maize seedlings after 28-days from Pythium, Rhizoctonia, and Fusarium in one of our soils with no history of PST-use; however, the seed treatment provided no added benefit in the other naïve soil compared to the control. Similar site-dependent results have been found by others (Weems et al., 2015), but further investigations are necessary to fully disentangle how repeatedly using combinations of fungicides and insecticides in the field affects fungicidal efficacy. Conclusions Our findings demonstrate for the first time that soil arthropod communities dramatically change with the initial introduction of crops pre-coated with insecticide-fungicides while communities with prolonged histories of seed treatment exposure are relatively unaffected by subsequent exposures. These results suggest pesticide seed treatments strongly filter the soil arthropod community within agricultural systems, and that the initial impact of seed treatments on the soil community surpasses the effect of subsequent applications. These results raise new concerns regarding the widespread use of seed treatments with neonicotinoids with respect to (1) farmers who are contemplating the adoption of this practice and (2) the potential for rapid losses in soil biodiversity in agroecosystems.
Publications
- Type:
Theses/Dissertations
Status:
Other
Year Published:
2017
Citation:
Managing the soil food web: Opportunities and Unintended Consequences
- Type:
Journal Articles
Status:
Other
Year Published:
2018
Citation:
Pesticide seed treatments differentially affect soil faunal communities and associated ecosystem services during the growing season.
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Progress 12/01/15 to 11/30/16
Outputs
Target Audience:General public, scientific community, United States Department of Agriculture, and University of New Hampshire undergraduates, Changes/Problems:I previously changed the scope of my second objective after finding only marginal differences in soil nitrogen (N-NO3 - ) and rates of surface residue decomposition in our field experiment. My newly revised second objective was to quantify the influence of pesticide seed treatments on soil food webs with prolonged and zero exposure to crop seeds pretreated with insecticide-fungicide mixtures. I am happy to report that my experiment for thesecond objective ran smoothly in May and the results are quite interesting. What opportunities for training and professional development has the project provided?One of the most rewarding aspects of the previous year was my experience training and mentoring an undergraduate. I hired Katie S. to work with me as a technician in Fall 2015. We were both pleasantly surprised when our employer-employee relationship grew into a mentor-mentee connection. As a mentor, I introduced Katie to UNH's Women in Science organization and helped her prepare for post-undergraduate employment. Through this experience, I improved my abilities to train future scientists, honed my mentoring skills, and, most importantly, helped another woman in science reach her goals. Additional experiences: 1. Guest lectures for Soil Ecology and Agroecology undergraduate courses at UNH. 2. Travel and present atthe 2016Tri-Societies of AmericaConference in Phoenix, AZ. Awarded best student poster for Soil Biology and Biochemistry division (November 2016). 3. Analyses of crop fungal pathogens. 4. UNH Three Minute Thesis competition - Awarded First Pkace and People's Choice Awards. (Video of presentation) 5. Travel and present at theNIFA FellowProject Director meeting in Washington, DC (August 2016). How have the results been disseminated to communities of interest?To date, I have presented these results to the NH general public, University of New Hampshire researchers, agricultural scientific community and at national conferences. Specifics of these activities are presented below. 1.UNH Three Minute Thesis competition (open to public) - Awarded First Pkace and People's Choice Awards. (Video of presentation) 2. Guest lectures for UNH Soil Ecology andAgroecology undergraduate courses. 3. 2016Tri-Societies of AmericaConference in Phoenix, AZ. Awarded best student poster for Soil Biology and Biochemistry division. 4. Virtual agroecology lab comprised of Agroecologists from Penn State, U. Minnesota, U. Illinois, USDA-ARS, and Bringham Young University. What do you plan to do during the next reporting period to accomplish the goals?1. Complete processing and analyzing the soil faunal communities we collected from the second sampling period of our greenhouse study. 2. Present results to NH farmers at the annula NOFA-NH conference (Jan 28, 2017) 3. Publish the PST field experiment data (previously reported) and the results from the greenhouse experiment.
Impacts
What was accomplished under these goals?
We conducted a greenhouse study in May to examine if pesticide seed treatments (PST)would elicit greater reductions in the richness and abundance of soil faunal communities in "naïve" (soils without a history of PST use) compared to "experienced" soils (soils with annual exposure to PST) because chronic exposure to PST would select for more PST tolerant organisms. For our experiment, we collected field soils from four sites near Durham, NH representing a gradient of PST exposure from naïve to experienced. We then planted maize with or without PST into each field soil in a completely randomized design with five replications and two sampling periods (14 and 28 days) in a climate-controlled greenhouse. Within these mesocosms, we then examined the effects of PST on the soil faunal community and crop root colonization of soil fungal pathogens. Results and Implications At 14 days, soil fauna communities with a history of PST exposure were less affected by the PST treatments compared to communities that were naïve to PSTs. In communities that were naïve, PST reduced the abundance of non-pest soil fauna and also altered species richness and evenness. PST appeared to protect maize from colonization by soil fungal pathogens for up to 28 days after planting, but only in the naïve hayfield soils. By 28 days, soil fungal pathogens had colonized maize roots in all other soils, regardless of whether maize seeds had been coated with PST or not. Even with the apparent protection from soil pathogens by PST in the hayfield soils, no differences in maize biomass were observed in any of the soils. Taken together, these results suggest that PSTs alter non-target soil faunal communities and these effects are strongest in soils where PSTs have not been used in the recent past. We plan to quantify the soil faunal communities measured at the 28-day harvest to determine if the impacts of PST on faunal abundance, richness, and evenness observed at the 14-day harvest persist over time. We are currently processing and analyzing the soil fauna data from our second sampling period.
Publications
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Progress 12/01/14 to 11/30/15
Outputs
Target Audience:Scientific Community, Farmers, United States Department of Agriculture Changes/Problems:After finding only marginal differences in soil nitrogen (N-NO3-) and rates of surface residue decomposition in our field experiment, we changed the focus of our proposed second objective. Our newly revised second objective is to quantify the influence of pesticide seed treatments on soil food webs with prolonged and zero exposure to crop seeds pretreated with insecticide-fungicide mixtures. Although this objective substantially differs from our proposed objective, we believe the results from this new objective will elucidate the interactions of pesticide seed treatments on soil food webs providing valuable insight to scientists and farmers. What opportunities for training and professional development has the project provided?Thus far, this project has provided L. Atwood with multiple opportunities for developing her career, including gaining further experience developing and conducting independent research, honing her abilities to effectively communicate science, and training an undergraduate interested in research. This project has provided L. Atwood's first opportunity to conduct manipulative laboratory incubations. Periodic meetings with R. Smith have further enhanced these opportunities through his thoughtful guidance and oversight. In addition, L. Atwood is actively mentoring and training a female undergraduate technician to assist with this project. This young woman had no prior experience handling and processing samples in a laboratory, but has proven to be keenly interested in agricultural research and a great asset to the project. Atwood's interest in supporting fellow women in science extends beyond her active guidance of the laboratory technician. Early this fall, she helped organize a UNH Women in Science Peer Mentor Social, in which undergraduate and graduate students interacted and paired off into mentor-mentee groups. L. Atwood was also invited to present her research at the Entomological Society of America / Tri-Societies of America Conference in Minneapolis, MN in mid-November in a session on systems-level approaches to agricultural research. Through this invitation, she met all the other session speakers, thus broadening her professional network significantly. How have the results been disseminated to communities of interest?Through this project L. Atwood has had the opportunity to travel and present her findings at two scientific conferences, the Ecological Society of America Conference (August 2015, Baltimore, MD) and the joint Entomological Society of America / Tri-Societies Conference (November 2015, Minneapolis, MN). At both of these conferences, Atwood established new connections with scientists in her field and gained new insights into the complex system that she studies. What do you plan to do during the next reporting period to accomplish the goals?To meet the remaining goals of this project, we plan to complete processing and analyzing all the data collected from the field and greenhouse experiments so that at least two manuscripts can be submitted for publication. We will also begin quantifying, through PLFA analyses and colonization assays, the pathogenic fungal community inhabiting the soils used in our greenhouse experiment. These data will provide further explanatory power for the differences in crop growth that we observed in our mesocosm experiment. We are currently on schedule for meeting the goals of this project.
Impacts
What was accomplished under these goals?
In 2015, this award supported the continuation of our field experiment at Russell E. Larson Agricultural Research Station in Rock Springs, PA. We deployed a litter bag study in which we measured the influence pesticide seed treatments have on surface litter decomposition. We also collected fauna inhabiting soil and surface residues three times during the growing season. These samples are currently being processed by L. Atwood and an undergraduate technician, also supported by this award. In July, we established a new greenhouse experiment aimed at quantifying both the initial impact of insecticide-fungicide seed treatments on "naïve" soil food webs - soil communities with no history of exposure to pesticide seed treatments - and the cumulative effect of seed treatments on "experienced" soil food webs - soil communities with a prolonged history of exposure to pesticide seed treatments. To do this, we extracted soil and associated faunal communities using intact soil cores collected from both naïve and experienced field sites. Soil cores were then placed in mesocosms and crop seeds, either pretreated with an insecticide-fungicide mixture or untreated, were planted directly into each mesocosm. At the end of the study, each experimental unit was destructively harvested and all soil mesofauna were extracted. Soil faunal communities are currently being processed in the laboratory.
Publications
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