EXAMINATION OF MIDWESTERN HOVER FLY (SYRPHIDAE) WINTER SURVIVAL TO IMPROVE POLLINATION EFFICIENCY AND CONSERVATION BIOLOGICAL CONTROL

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: AFRI COMPETITIVE GRANT
• Reporting Frequency: Annual
• Accession No.: 1019183
• Grant No.: 2019-67011-29504
• Cumulative Award Amt.: $119,990.00
• Proposal No.: 2018-07721
• Project Start Date: May 1, 2019
• Project End Date: Jul 31, 2021
• Grant Year: 2019
• Program Code: [A7101]- AFRI Predoctoral Fellowships

Recipient Organization
UNIVERSITY OF ILLINOIS
2001 S. Lincoln Ave.
URBANA,IL 61801

Performing Department
Entomology

Non Technical Summary
In thisera of expansive agriculture, unsustainable pest-control practices contributing to pesticide resistance andpollinator decline is rampant, and much basic research is needed to reverseor slow these effects.One method of reducing these problems is Conservation Biological Control which takes advantage ofnaturally present predators (mostly other arthropods) that attack pests. One group of beneficial insects that can be targeted and whichhas received considerably lessattention is hover flies (family Syrphidae). Hover flies provide multiple ecosystem servicesthroughout their life cycle which can improvecrop yields: adult flies are pollinators of a variety of crops while many larvae are voracious predators of a soft-bodied pest insects including aphids. Despite their important roles, little is known about how North American species survive winter, which is critical to ensuring species are present during crucial times for crops. This predoctoral research project conducted by Scott Clem (project director and doctoral candidate) and advised by Dr. Alexandra Harmon-Threatt (primary mentor and assistant professor), both at the University of Illinois Urbana-Champaign, will address three questions related to hover fly winter survival: 1) Investigate the spring migration dynamics andsources of hover flies in agricultural systems using stable hydrogen isotopes, 2) Quantify hover fly overwintering capability, and 3) Determine how soil insecticides affect hover fly overwintering survival. Improvingtheir winter survival will result in decreased pest-load,improved pollination,and therefore enhanced crop yield.Data obtainedfrom this project will be used to address key knowledge gaps in our understanding of hover fly ecology, resulting in improved pollinator conservation and sustainable agriculture.

Animal Health Component

40%

Research Effort Categories

Basic

60%

Applied

40%

Developmental

0%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
211	3095	1070	25%
215	3110	1130	25%
216	3095	1130	25%
205	5220	1150	25%

Knowledge Area
211 - Insects, Mites, and Other Arthropods Affecting Plants; 215 - Biological Control of Pests Affecting Plants; 205 - Plant Management Systems; 216 - Integrated Pest Management Systems;

Subject Of Investigation
3095 - Other non-bee pollinators, general; 3110 - Insects; 5220 - Pesticides;

Field Of Science
1130 - Entomology and acarology; 1070 - Ecology; 1150 - Toxicology;

Keywords

conservation biological control

hover fly

migr

pollination

syrphidae

winter survival strategies

Goals / Objectives
The overall objective of this research is to understand the winter survival of beneficial hover flies (Syrphidae), information which is essential for improving crop pollination and enhancing conservation biological control (CBC) of crop pests.Objective 1 is to investigate the spring migration dynamics and develop a North American hover fly isoscape to determine sources of hover flies in agricultural systems.Objective 2 is to quantify hover fly winter survival ability by measuring presence of antifreeze proteins in fall.Objective 3 is to determine how farm contaminants affect hover fly behavaior and overwintering capability. Information on hover flies and data from these three objectives will be distributed to stakeholders including academic and Extension professionals, farmers, land managers, and the general public through peer-reviewed publications, Extension publications, presentations, webinars, and university social-media accounts.

Project Methods
Objective 1: Investigate the spring migration dynamics and develop a North American hover fly isoscape to determine sources of hover flies in agricultural systemsRationale and significance: The migration ecology of insects and its implications for humans and agriculture is an area of research that is vastly under-studied. In the UK, 3,200 tons of insects were estimated migrating in high-altitude air-currents above the region annually, some of which were hover flies like Episyrphus balteatus that can travel up to 111km in less than three days. These flies migrate southward in the fall with a northward migration in the spring. Large-scale migrations have major implications for farmers, especially if few hover flies are overwintering locally on their propertiesbecause it determines whether certain crops will be successfully pollinatedand aphids will be suppressed. No studies to date, other than my own preliminary research, have investigated the migratory tendencies of North American hover flies and the implications for agriculture.Insect migration can be investigated using stable hydrogen isotopes, which fluctuate predictably on a north-south gradient throughout North America. Insects accumulate isotopes into their tissues as larvae, which become permanently fixed in adults revealing signatures specific to their larval habitat. Adult insects with stable isotope frequencies that differ from local patterns, therefore, are believed to have immigrated to the area. I am currently using this technique to test for fall migratory hover flies over two years in Urbana, Illinois, finding that during September of 2017 many individuals exhibit isotopic signatures indicative of a southward migration. The next step is to examine the broader picture by investigating a possible spring migration event and establishing an isoscape to reveal the precise source of flies. Isoscapes are created by analyzing the known local insect tissues from different localities throughout a geographical region and have been implemented in monarch and dragonfly migration studies to reveal the natal origins of the insects. By knowing the origins of migratory hover flies, we will have a better understanding of these seasonal cycles. Thus, we can train farmers to accommodate spring and fall migrants by limiting insecticide use and planting wildflower strips for nectar. Implementing these practices would increase hover fly abundance, enhancing crop yield by improving CBC and pollination effectiveness, thus relating directly to the PHPPP AFRI Program Priority Area.Methods and Expected Outcomes: Three hover fly species were selected for spring migration analysis based on preliminary data: A. obliqua, Eu. americanus, and S. ribesii. Ten females of each species will be collected every two weeks from March-September in Urbana, Illinois prairies via hand netting. The fixed hydrogen isotopic ratios in wings and legs of these wild-caught individuals will then be compared to isoscape values as well as known local individuals reared in the lab on local aphids (Uroleucon sp.). Deuterium isotopic analysis of all chitin fragments will be conducted in the lab of Dr. Keith Hobson at Western University in London, Ontario. An ANOVA will be used to compare these data across sampling groups.The hover fly isoscape will be created using the deuterium isotopic values from presumed non-migratory hover flies collected throughout eastern North America. We will also obtain specimens by collaborating with insect museums and traveling to certain locations when necessary to collect. Once all isotope values from approximately 250 specimens have been retrieved, isoscapes will be created using GIS software.Objective 2: Quantify hover fly winter survival ability by measuring presence of antifreeze proteins in fallRationale and significance: While some hover flies within a population migrate, others may remain local, surviving the freezing conditions of winter via diapause. The aspects of this strategy among North American hover flies remain poorly understood and it is unknown which species are freeze-tolerant or intolerant. Freeze-tolerant insects are capable of enduring extracellular freezing using ice-nucleating agents, antifreeze proteins, and other means to promote safe freezing, while freeze-intolerant insects cannot survive freezing and must avoid it. By placing hover fly species into these categories, we can make inferences about winter survival and thus aphid suppression in the spring. I propose to investigate the presence of antifreeze proteins in several individuals from different species collected in late fall to understandwhich species overwinter locallyand which overwinter as adults. These data will makeimportant contributions to the scientific literature and can be used to predict fly survival after a given winter and thus the effectiveness of CBC in the spring.Methods and expected outcomes: Three species will be examined: T. marginatus, A. obliqua, and Eu. americanus. Hover flies are thought to overwinter underground as either final instar larvae or adults, and preliminary results suggest that at least one of these species, A. obliqua, overwinters as gravid females. Ten adult males and females of each species will be sampled during early October to maximize the probability of capturing winter morphs which live longer and are more adapted to winter conditions. Hemolymph (i.e. insect blood) will then be extracted and screened for thermal hysteresis, a process which reveals the presence of antifreeze proteins. The final published product will be a list of species and sexes that produce antifreeze proteins for winter survival. This will be used to create outreach materials which will be distributed with information on how to increase hover fly abundance on properties.Objective 3: Determine how farm contaminants affect hover fly behavior and overwintering capabilityRationale and significance: An important question related to conservation biological control and pollinator conservation is how beneficial arthropods are affected by the wide-spread use of neonicotinoid seed-coatings which contaminate many agricultural soils. Only 1.6-20% of the active ingredient on these seed coatings is absorbed into the plant, leaving the rest to enter the soil. These insecticides are detrimental to hover flies and other beneficial insects, but few studies have investigated the effects on non-target insects living in contaminated soil and none have examined overwintering hover flies. I therefore propose to investigate whether the presence of insecticide from seed coatings can affect the survival of overwintering hover flies and other beneficial arthropods, which may explain why our preliminary study found so few overwintering on agricultural properties in the spring.Methods and Expected Outcomes: To investigate this question, a field-based experiment will measure the emergence of hoverflies in known contaminated soils using 60 x 60cm tent-like emergence traps which cover an area of soil and capture emerging insects. Nine traps will be placed on 10 x 10m plots of restored prairie habitat previously treated with clothianidin at a rate of 36.3kg of active ingredient per acre to mimic seed coatings. They will then be compared with traps on plots given no insecticide treatment. Traps will be monitored on five paired sites biweekly from March through June, as these are the months when overwintering insects are expected to emerge. Differences between abundance and species richness of hover flies and other important insects captured in plots contaminated with insecticide and those without will be assessed using a non-parametric Wilcoxon signed-rank test. Finally, soil samples within the plots will be sent to the University of Illinois Metabolomics Lab to test for insecticide content at the beginning of both sampling years.

Progress 05/01/19 to 07/31/21

Outputs
Target Audience:Target audiences included farmers, land managers, conservationists, ecologists, entomologists, Extension specialists, toxicologists, and the general public. Changes/Problems:The only major changes have been for Objectives 2 and 3. For Objective 2, we answered the same question but used a different methodology. For Objective 3, because we did not capture hover flies we decided to examine the effects of neonicotinoids on overwintering carabid beetles. I have described these changes in the "accomplishments" section of this report. What opportunities for training and professional development has the project provided?This project has provided the Project Director, Scott Clem, with a multitude of professional development training. He has gained experience conducting professional Extension and scientific presentations, as well as writing both types of publications. He has also gained more experience designing experiments, collecting data, analyzing data, and summarizing the final results. Scott also completed his doctoral degree during the predoctoral fellowship and has successfully been granted a NIFA EWD postdoctoral fellowship. During 2020, the COVID-19 pandemic disallowed many professional development opportunities but did not eliminate them entirely. Scott was planning to attend the International Congress of Entomology in Helsinki, Finland, but this meeting was cancelled. Instead, he was able to present results of this project at two virtual Entomology Society of America meetings. He plans to present at the now 2022 International Congress Meeting as well as the 2021 Entomology Society of America national meeting in Denver, Colorado. How have the results been disseminated to communities of interest?Results have been presented at six different professional conferences: five Entomology Society of America meetings and one Ecological Society of America meeting. Scott also discussed results of these studies at the Wildlife on the Farm Field Day in Anchor, Illinoisin front of numerous farmers, prairie conservationists, and land managers. He has published two peer-reviewed open access research papers from this project and has one in review in the prestigious journal Ecological Monographs. He has plans to produce two more, resulting in five total published manuscripts. In April of 2021, Scott defended his dissertation which encompassed these studies. This dissertation was published in August of 2021. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Hover flies (Diptera: Syrphidae) are prevalent in landscapes throughout North America and can provide sustainable and cost-effective options for controlling crop pests and enhancing pollination services for farmers. Little, however, is known about their seasonal biology, winter survival strategies, and how they are impacted by insecticides prevalent in their environment. The focus of this fellowship is to investigate aspects relating to: 1) Long-distance hover fly seasonal migration, 2) Local overwintering, and 3) Determining how field-relevant levels of neonicotinoid insecticides affect hover flies. This information is vital for conserving these insects and developing successful biological control schemes. Thus, it is important for farmers, land managers, conservationists, entomologists, Extension professionals, and the general public. All three objectives of the project were fully completed, with manuscripts awaiting publication.Specific results and accomplishments of the projectsare discussed in detail below. Objective 1: Investigate the spring migration dynamics and develop a North American hover fly isoscape to determine sources of hover flies in agricultural systems For the first part of Objective 1, we obtained stable isotope ratio readings for Eupeodes americanus and Allograpta obliqua hover flies captured in Illinois during spring, and Illinois and Alabama during fall. We did not find evidence of a northward migration during spring, although this does not mean it does not exist. This probably means that spring hover fly migration is much less dramatic compared to fall migration. For the second part of Objective 1, we examined how far these hover flies travel during the fall by assessing natal origins of the migratory Eu. americanus and non-migratory A. obliqua collected in northern Alabama. We built hover fly δ2H isoscapes using a calibration algorithm of water and hover fly tissues. We then used these isoscapes to assign grouped natal origins of hover flies using an IsoriX workflow. Consistent with preliminary data, Eu. americanus was highly migratory whereas A. obliqua was mostly non-migratory. Several Eu. americanus specimens were estimated to have traveled between 1,000 and 3,000 km from the midwestern United States and Canada to Alabama. These results were compiled into Chapter 2 of Scott Clem's dissertation and will be published as a separate publication. Objective 2: Quantify hover fly winter survival ability by measuring presence of antifreeze proteins in fall For Objective 2, we decided to change how we wanted to approach the question at hand. To quantify winter survival ability, we examined supercooling points of hover flies instead of antifreeze proteins. Supercooling points are an easier way to estimate lower lethal temperature and thus cold tolerance. Using this metric, and combining data from 2018 and 2019, we have determined that the migratory Eupeodes americanus hover fly is less cold tolerant than the non-migratory Allograpta obliqua hover fly. This suggests that migration is a mechanism by which Eu. americanus avoids winter conditions. These two species, therefore, may be useful for controlling aphids at different times of the year. This objective was incorporated into Chapter 1 of Scott Clem's dissertation and the ensuing publication that is in revision in Ecological Monographs. Objective 3: Determine how farm contaminants affect hover fly overwintering capability and behavior For the first part of Objective 3, we conducted the experiment as proposed by using emergence tents to sample overwintering hover flies in neonicotinoid-contaminated and uncontaminated soils. Unfortunately, we did not capture any overwintering hover flies. Instead, we decided to examine the abundance and species richness of another beneficial insect prevalent in trap captures: carabid beetles. Carabid beetles are common throughout agricultural landscapes and are often used as indicators of environmental quality. This makes them ideal candidates for assessing the effects of neonicotinoid soil-contaminants. Preliminary results suggest that the insecticide applied the previous season had little effect on carabid beetle communities in the early spring. While official results are forthcoming, preliminary findings indicate that neonicotinoids do not impact carabid beetle communities. We did find, however, that landscape factors like field borders are highly impactful on overwintering predator communities. We have fully completed the second part of Objective 3. We examined whether hover flies can distinguish neonicotinoid insecticides in food rewards (sucrose solution) using a two-choice experiment. Results suggest that Eristalis hover flies exhibit behavioral resistance to the insecticide. This project in its entirety was just published in the journal Plos One under the title "Can anthophilous hover flies (Diptera: Syrphidae) discriminate neonicotinoid insecticides in sucrose solution?" We discuss the significance of our findings in this paper. In brief, because some hover flies can detect these insecticides in food rewards, it is possible that they can avoid them in field scenarios. Thus, they may be less impacted by insecticides compared to other pollinators like bees. We stress that more data in a field scenario is essential to further understand these interactions.

Publications

• Type: Journal Articles Status: Under Review Year Published: 2022 Citation: Clem, C.S., K.A. Hobson and A.N. Harmon-Threatt. 2022. Evidence and mechanisms of long-distance migration among Nearctic hover flies (Diptera: Syrphinae). Ecological Monographs.
• Type: Journal Articles Status: Awaiting Publication Year Published: 2022 Citation: Clem, C.S., K.A. Hobson and A.N. Harmon-Threatt. 2022. Flies in flight: New stable isotopic evidence of long-distance migratory flight of a North American hover fly.
• Type: Journal Articles Status: Other Year Published: 2022 Citation: Tetlie, J.R., C.S. Clem and A.N. Harmon-Threatt. 2022. Examining impacts of Neonicotinoid insecticides on soil-dwelling beneficial arthropods. In Development.

Progress 05/01/20 to 04/30/21

Outputs
Target Audience:Target audiences include farmers, land managers, conservationists, ecologists, entomologists, Extension specialists, toxicologists, and the general public. Changes/Problems:The only major changes have been for Objectives 2 and 3. For Objective 2, we are still answering the same question, just using a different methodology. For Objective 3, because we did not capture hover flies we decided to examine the effects of neonicotinoids on overwintering carabid beetles. I have described these changes in the "Accomplishments" section of this report. What opportunities for training and professional development has the project provided?This project has provided the Project Director, Scott Clem, with numerous professional development training opportunities. He has gained experience conducting professional Extension and scientific presentations, as well as writing both types of publications. He has also gained more experience designing experiments, collecting data, analyzing data, and summarizing the final results. During 2020, the COVID-19 pandemic disallowed many professional development opportunities but did not eliminate them entirely. Scott was planning to attend the International Congress of Entomology in Helsinki, Finland, but this meeting was cancelled. Instead, he was able to present results of this project at two virtual Entomology Society of America meetings. How have the results been disseminated to communities of interest?Results have been presented at five different professional conferences: four Entomology Society of America meetings and one Ecological Society of America meeting. Scott also discussed results of these studies at the Wildlife on the Farm Field Day in Anchor, Illinoisin front of numerous farmers, prairie conservationists, and land managers. He has published two peer-reviewed open access research papers from this project with plans to produce at least three more. In April of 2021, Scott defended his dissertation which encompassed these studies. This dissertation will be published in August of 2021. What do you plan to do during the next reporting period to accomplish the goals?All objectives have been completed except for part of Objective 3. These data will be disseminated and included as part of the final report.

Impacts
What was accomplished under these goals? Hover flies (Diptera: Syrphidae) are prevalent in landscapes throughout North America and can provide sustainable and cost-effective options for controlling crop pests and enhancing pollination services for farmers. Little, however, is known about their seasonal biology, winter survival strategies, and how they are impacted by insecticides prevalent in their environment. The focus of this fellowship is to investigate aspects relating to: 1) Long-distance hover fly seasonal migration, 2) Local overwintering, and 3) Determining how field-relevant levels of neonicotinoid insecticides affect hover flies. This information is vital for conserving these insects and developing successful biological control schemes. Thus, it is important for farmers, land managers, conservationists, entomologists, Extension professionals, and the general public. Objectives 1, 2, and most of 3 are fully completed. Specific results and accomplishments of the second project period are discussed in detail below. Objective 1: Investigate the spring migration dynamics and develop a North American hover fly isoscape to determine sources of hover flies in agricultural systems For the first part of Objective 1, we obtained stable isotope ratio readings for Eupeodes americanus and Allograpta obliqua hover flies captured in Illinois during spring, and Illinois and Alabama during fall. We did not find evidence of a northward migration during spring, although this does not mean it does not exist. This probably means that spring hover fly migration is much less dramatic compared to fall migration. For the second part of Objective 1, we examined how far these hover flies travel during the fall by assessing natal origins of the migratory Eu. americanus and non-migratory A. obliqua collected in northern Alabama. We built hover fly δ2H isoscapes using a calibration algorithm of water and hover fly tissues. We then used these isoscapes to assign grouped natal origins of hover flies using an IsoriX workflow. Consistent with preliminary data, Eu. americanus was highly migratory whereas A. obliqua was mostly non-migratory. Several Eu. americanus specimens were estimated to have traveled between 1,000 and 3,000 km from the midwestern United States and Canada to Alabama. These results were compiled into Chapter 2 of Scott Clem's dissertation and will be published as a separate publication. Objective 2: Quantify hover fly winter survival ability by measuring presence of antifreeze proteins in fall For Objective 2, we decided to change how we wanted to approach the question at hand. To quantify winter survival ability, we examined supercooling points of hover flies instead of antifreeze proteins. Supercooling points are an easier way to estimate lower lethal temperature and thus cold tolerance. Using this metric, and combining data from 2018 and 2019, we have determined that the migratory Eupeodes americanus hover fly is less cold tolerant than the non-migratory Allograpta obliqua hover fly. This suggests that migration is a mechanism by which E. americanus avoids winter conditions. These two species, therefore, may be useful for controlling aphids at different times of the year. This objective was incorporated into Chapter 1 of Scott Clem's dissertation and the ensuing publication that was submitted to Ecological Monographs. Objective 3: Determine how farm contaminants affect hover fly overwintering capability and behavior For the first part of Objective 3, we conducted the experiment as proposed by using emergence tents to sample overwintering hover flies in neonicotinoid-contaminated and uncontaminated soils. Unfortunately, we did not capture any overwintering hover flies. Instead, we decided to examine the abundance and species richness of another beneficial insect prevalent in trap captures: Crabid beetles. Carabid beetles are common throughout agricultural landscapes and are often used as indicators of environmental quality. This makes them ideal candidates for assessing the effects of neonicotinoid soil-contaminants. Preliminary results suggest that the insecticide applied the previous season had little effect on carabid beetle communities in the early spring. While official results are forthcoming, preliminary findings indicate that neonicotinoids do not impact carabid beetle communities. We did find, however, that landscape factors like field borders are highly impactful on overwintering predator communities. We have fully completed the second part of Objective 3. We examined whether hover flies can distinguish neonicotinoid insecticides in food rewards (sucrose solution) using a two-choice experiment. Results suggest that Eristalis hover flies exhibit behavioral resistance to the insecticide. This project in its entirety was just published in the journal Plos One under the title "Can anthophilous hover flies (Diptera: Syrphidae) discriminate neonicotinoid insecticides in sucrose solution?" We discuss the significance of our findings in this paper. In brief, because some hover flies can detect these insecticides in food rewards, it is possible that they can avoid them in field scenarios. Thus, they may be less impacted by insecticides compared to other pollinators like bees. We stress that more data in a field scenario is essential to further understand these interactions.

Publications

• Type: Journal Articles Status: Published Year Published: 2021 Citation: Clem, C. Scott and A. Harmon-Threatt. 2021. Field borders provide winter refuge for beneficial predators and parasitoids: A case study on organic farms. Journal of Insect Science, 21(3).
• Type: Journal Articles Status: Submitted Year Published: 2021 Citation: Clem, C. Scott, K.A. Hobson and A.N. Harmon-Threatt. 2021. Evidence and mechanisms of long-distance migration among Nearctic hover flies (Diptera: Syrphinae): The case for a beneficial predacious and pollinating insect. (Submitted, Ecological Monographs).
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Clem, C. Scott. 2020. Assessing capacity of prairie-strip field borders to provide winter refuge for pest natural enemies (Poster Presentation). 22nd Annual Graduate Student Symposium, hosted by Graduates in Ecology and Evolutionary Biology, Urbana, Illinois, February 8, 2020. Poster Presentation.
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Clem, C. Scott 2020. Where do they come from? Estimating natal origins of North American migratory hover flies (Diptera: Syrphinae) using stable deuterium isotopes. Entomology Society of America virtual meeting Nov. 16-19, 2020. Oral Presentation.
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Clem, C. Scott. 2021. Estimating natal origins of North American migratory hover flies (Diptera: Syrphinae) using stable deuterium isotopes. 23rd Annual Graduate Student Symposium, hosted by Graduates in Ecology and Evolutionary Biology, Urbana, Illinois, February 6, 2021. Oral Presentation.
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Clem, C. Scott. 2021. Examining North American hover fly (Diptera: Syrphidae) migration using stable deuterium isotopes. Maine Entomological Society seminar series, March 4, 2021. Invited Oral Presentation.
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Clem, C. Scott. 2021. Where do they come from? Examining North American hover fly (Diptera: Syrphidae) migration using stable deuterium isotopes. University of California Berkeley Essig Brunch Entomology Seminar, March 12, 2021. Invited Oral Presentation.
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Clem, C. Scott. 2021. Assessing winter survival behaviors of beneficial arthropods, with a special focus on the long-distance migratory ecology of Nearctic hover flies (Diptera: Syrphinae). Doctoral Exit Seminar, April 27, 2021. Oral Presentation.
• Type: Conference Papers and Presentations Status: Published Year Published: 2021 Citation: Clem, C. Scott. 2021. Assessing long-distance migratory capacity of Nearctic hover flies (Diptera: Syrphinae). North Central Branch Entomological Society of America Virtual Meeting. June 21-23, 2021. Oral Presentation.
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2022 Citation: Clem, C. Scott. 2022. Evidence of long-distance hoverfly (Diptera: Syrphidae) migration through the Midwestern United States: A stable isotope study. International Congress of Entomology meeting in Helsinki, Finland. July, 2022. Oral Presentation (Planned).
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2021 Citation: Clem, C. Scott. 2021. Mechanisms of long-distance hover fly (Diptera: Syrphidae) migration. Entomological Society of America National Meeting in Denver, Colorado. October 31 - November 3, 2021. Oral Presentation (Planned).
• Type: Theses/Dissertations Status: Published Year Published: 2021 Citation: Clem, C. Scott. 2021. Assessing adaptive winter behaviors of beneficial arthropods, with a focus on the long-distance migratory ecology of Nearctic hover flies (Diptera: Syrphidae). University of Illinois at Urbana-Champaign Department of Entomology Dissertation.
• Type: Journal Articles Status: Awaiting Publication Year Published: 2022 Citation: Clem, C. Scott. 2022. Estimating natal origins of North American migratory hover flies (Diptera: Syrphidae) using stable hydrogen isotopes. In Development.

Progress 05/01/19 to 04/30/20

Outputs
Target Audience:Target audiences included farmers, land managers, conservationists, ecologists, entomologists, Extension specialists, toxicologists, and the general public. Changes/Problems:The only major changes have been for Objectives 2 and 3. For Objective 2, we are still answering the same question, just using a different methodology. For Objective 3, because we did not capture hover flies we decided to examine the effects of neonicotinoids on overwintering carabid beetles. I have described these changes in the "accomplishments" section of this report. There is one problem concerning expenditures for the International Congress of Entomology meeting in Helsinki, Finland for which Scott planned to attend. The meeting was originally scheduled for July 2020 but has been post-poned to summer of 2021 due to the COVID-19 pandemic. NIFA has already paid for non-refundable conference fees and the flight which may be rescheduled. The problem is that this meeting now occurs after the completion of the fellowship. We are hoping that under these peculiar events NIFA will agree to still pay travel costs for Scott to attend this meeting. What opportunities for training and professional development has the project provided?This project so far has provided the Project Director, Scott Clem, with numerous professional development training opportunities. He has gained experience conducting professional Extension and scientific presentations, as well as writing both of these types of publications. He has also gained more experience designing experiments, collecting data, analyzing data, and summarizing the final results. Over the next year he will be looking for professional Extension and/or agricultural research positions. How have the results been disseminated to communities of interest?Results have been presented at two different professional conferences: the Entomology Society of America meeting and the Ecological Society of America meeting. Scott also discussed results of these studies at the Wildlife on the Farm Field Day in Anchor, Illinoisin front of numerous farmers, prairie conservationists, and land managers. He has also published one peer-reviewed open access research paper from this project. What do you plan to do during the next reporting period to accomplish the goals?We plan to complete all objectives proposed. At this point, data analysis and publication is the main thing left to accomplish for these goals. Scott Clem plans to present these data at the 2020 National Entomology Society of America meeting in November, and the post-poned July 2021 International Congress of Entomology meeting in Helsinki, Finland. Unfortunately, due to concerns with COVID-19, other in-person presentations are hindered. Scott is currently working on a Hoverflies of Illinois Extension publication to be distributed to farmers, land managers, Extension personnel, entomologists, and anyone in the general public who wished to learn about the importance of hover flies. This will be completed and included in the final report.

Impacts
What was accomplished under these goals? Hover flies (Diptera: Syrphidae) are prevalent in landscapes throughout North America and can provide sustainable and cost-effective options for controlling crop pests and enhancing pollination services for farmers. Little, however, is known about their seasonal biology, winter survival strategies, and how they are impacted by insecticides prevalent in their environment. The focus of this fellowship is to investigate aspects relating to 1) long-distance hover fly seasonal migration, 2) local overwintering, and 3) determining how field-relevant levels of neonicotinoid insecticides affect hover flies. This information is vital for conserving these insects and developing successful biological control schemes. Thus, it is important for farmers, land managers, conservationists, entomologists, Extension professionals, and the general public. Specific results and accomplishments of the first project period are discussed in detail below. Objective 1: Investigate the spring migration dynamics and develop a North American hover fly isoscape to determine sources of hover flies in agricultural systems. For Objective 1, we have obtained stable isotope ratio readings for Eupeodes americanus and Allograpta obliqua hover flies captured in Illinois during spring, and Illinois and Alabama during fall. We did not find evidence of a northward migration during spring, although this does not mean it does not exist. This probably means that spring hover fly migration is much less dramatic compared to fall migration. Isotopic readings from fall-captured Illinois and Alabama indicate that several individual Eupeodes americanus are migrants that arrived from further north. Additionally, we have reared several hover flies on different sources of water and have obtained a fractionation rate estimation. Our next step is to use this estimation to create an isoscape of hover fly wing deuterium isotope values, as discussed in our proposal. We will use this to estimate natal origins of hover flies we believe to be migratory. These results have much significance. Because we know that these flies appear to be migrating on a continental scale, we should encourage farmers, pollinator conservationists, and land managers to maintain fall-flowering plants so that more of these insects survive and provide their beneficial services. Objective 2: Quantify hover fly winter survival ability by measuring presence of antifreeze proteins in fall. For Objective 2, we decided to change how we wanted to approach the question at hand. To quantify winter survival ability, we examined supercooling points of hover flies instead of antifreeze proteins. Supercooling points are an easier way to estimate lower lethal temperature and thus cold tolerance. Using this metric, and combining data from 2018 and 2019, we have determined that the migratory Eupeodes americanus hover fly is less cold tolerant than the non-migratory Allograpta obliqua hover fly. This suggests that migration is a mechanism by which E. americanus avoids winter conditions. These two species, therefore, may be useful for controlling aphids at different times of the year. Objective 3: Determine how farm contaminants affect hover fly overwintering capability and behavior. For the first part of Objective 3, we conducted the experiment as proposed by using emergence tents to sample overwintering hover flies in neonicotinoid-contaminated and uncontaminated soils. Unfortunately, we did not capture any overwintering hover flies. Instead, we decided to examine the abundance and species richness of another beneficial insect prevalent in trap captures: carabid beetles. Carabid beetles are common throughout agricultural landscapes and are often used as indicators of environmental quality. This makes them ideal candidates for assessing the effects of neonicotinoid soil-contaminants. Preliminary results suggest that the insecticide applied the previous season had little effect on carabid beetle communities in the early spring. Official results are forthcoming. We have fully completed the second part of Objective 3. We examined whether hover flies can distinguish neonicotinoid insecticides in food rewards (sucrose solution) using a two-choice experiment. Results suggest that Eristalis hover flies exhibit behavioral resistance to the insecticide. This project in its entirety was just published in the journal Plos One under the title "Can anthophilous hover flies (Diptera: Syrphidae) discriminate neonicotinoid insecticides in sucrose solution?" We discuss the significance of our findings in this paper. In brief, because some hover flies can detect these insecticides in food rewards, it is possible that they can avoid them in field scenarios. Thus, they may be less impacted by insecticides compared to other pollinators like bees. We stress that more data in a field scenario is essential to further understand these interactions.

Publications

• Type: Journal Articles Status: Published Year Published: 2020 Citation: Clem, C.S., Sparbanie, T.M., Luro, A.B. and Harmon-Threatt, A.N. 2020. Can anthophilous hover flies (Diptera: Syrphidae) discriminate neonicotinoid insecticides in sucrose solution? PLoS ONE 15(6): e0234820. https://doi.org/10.1371/journal.pone.0234820
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Clem, C.S. and A. Harmon-Threatt. 2019. Winter is coming: Do Midwestern hover flies (Syrphidae) migrate south during autumn? A study using stable isotopes (2H) (oral presentation). Ecological Society of America Meeting, Louisville, KY, August 11-16, 2019.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2019 Citation: Clem, C.S. and A. Harmon-Threatt. 2019. Syrphing the wind: Investigating migratory strategies and cold tolerance of midwestern hover flies (Diptera: Syrphidae) (oral presentation) Section Symposium: "Callows and Pre-Imaginal" Professionals of Pollination Research. Entomological Society of America national meeting, Saint Louis, MO, November 17-20, 2019.
• Type: Conference Papers and Presentations Status: Submitted Year Published: 2021 Citation: Clem, C.S. and A. Harmon-Threatt. 2021. Evidence of long-distance hoverfly (Diptera: Syrphidae) migration through the Midwestern United States: A stable isotope study (2H). Planned oral presentation at International Congress of Entomology meeting in Helsinki, Finland.
• Type: Conference Papers and Presentations Status: Submitted Year Published: 2020 Citation: Clem, C.S. and A. Harmon-Threatt. 2020. Assigning natal origins to North American migratory hover flies (Eupeodes americanus). Planned oral presentation at Entomological Society of America national meeting in Orlando, FL.