Location: Pollinator Health in Southern Crop Ecosystems Research
2023 Annual Report
Objectives
1. Determine pesticide risks to honey bees, both by laboratory assays and field studies in southern cropping systems, including the mode of action of insecticides on bee pollinators and interactions with other pesticides.
2. Develop IPM systems to mitigate the effects of pesticides on bees in these systems.
3. Determine the role of non-crop vegetation in the health of bees in these systems, with a focus on enhancing bee forage habitat.
4. Conduct studies on native bee diversity and biology in southern cropping systems to improve the use of local bee species for pollination of regional crops such as squash and berries.
5. Conduct studies on aerial and ground application of pesticides, examining drift patterns and design equipment and spray adjuvants/dispensers that uses precision application to minimize off-target application onto adjacent non-cropping areas associated with bee habitat.
Approach
This new Research Unit will focus on how to improve both native and honey bee health as well as improving natural habitat and minimizing risk to stressors including pesticides and pests in a way that is beneficial to both beekeepers and farmers. The southern United States has traditionally been an area of high row crop agriculture with often high pest pressure than routinely needs synthetic pesticides to keep populations below economic injury levels. These areas are only now seeing the influx of commercial beekeepers that traditionally have been located in other areas of the U.S. Therefore, there is a need to determine ways to increase the health of both managed honey bees as well as native bees that are often needed for pollination services for farmers as well as producing honey for the commercial beekeeper. In addition, there is a lack of knowledge in the overall ecology of non-crop forage (i.e. weeds and native vegetation) to provide suitable habitat for bees as well as determining the risk of certain pesticides on bee health. Finding answers on which strategies increase bee health while being feasible and economical both to the farmer and commercial beekeeper is of the highest priority. Reducing pollinator losses by improving bee health is essential for consistently providing adequate bee populations for crop pollination and ensuring the productivity of U.S. crops that require bee pollination. Identification of particularly damaging chemical pesticides as well as improved application strategies that minimize impact on non-target organisms, such as bees, will inform exposure risks that may be mitigated. Conserving the diversity of non-Apis bees, including bumble bees, alfalfa leafcutter bees, and blue orchard bees, is essential for pollinating certain agricultural crops in addition to hundreds of species of native plants that can be forage for managed honey bees. Progress in NP305 will be accelerated by the information provided by this project. All information generated will be made available through various research publications outlets including outreach using University extension personnel. In addition, the new Unit will collaborate extensively with external partners including landgrant Universities and other federal agencies through outgoing NACAs and interagency agreements.
Progress Report
We continued to make collections and identify native bees from a variety of habitats across the southeastern United States. Samples were collected with a combination of collection techniques including modified pan traps (bee bowls), malaise traps, vane traps, and net sampling. All specimens have been cleaned, pinned, mounted, and entered into a database. Common species have been completely identified and ARS researchers are working with other taxonomists to identify rare taxa. Specimens of species new to the state or of significance have been deposited with regional, national, and international entomological collections. This baseline information is being used to examine potential impacts of local agricultural production practices on these insects and compare with production practices and pollinator communities in other regions.
Findings from a single year large cage trial using three varieties of soybeans, each in a different maturity group, were analyzed. These varieties were each replicated three times in each cage, and each set of three cages received a pollinator treatment (honey bees only, no bees, or access by all bees). Soybean samples have been analyzed by using several metrics, and bee specimens are in the final processes of being identified. A second year of the study was completed using two commercial varieties of soybeans and several heirloom varieties.
Multiple species of native bees from the southeastern United States have been collected and are preserved at -80C toward this project and the agency’s larger “Beenome100” project. The beenome project aims to sequence the genomes of 100 native bees in collaboration with university colleagues from the University of Illinois and other ARS researchers. Several of the bee species collected from MS have completed both HiFi and HiC sequencing, and other locally collected species are in the pipeline.
ARS researchers have been studying the toxicity of conventional pesticides on honey bees, while also looking into non-conventional forms of insect control. We are currently assaying the effects of Radiant, Warden Cereals HR, and Elevest formulations on honey bees, but we are also working on Heligen, a biological pesticide (Nucleopolyhedrovirus) used to control lepidopteran pests in cotton. We have also been studying the effects of Bisabolene, Cinnamaldehyde, and Eugenol, compounds found in certain essential oils, and EcoTec Plus, an essential oil mixture sold as an insecticide. Essential oils are increasingly seen as possible alternatives to conventional pesticides, and each of these compounds has been found to be effective in eliminating a significant pest, such as mosquitos. If their use becomes mainstream, we will need to understand their effects on pollinators such as honey bees.
In addition, we have collaborated with scientists from Mississippi State University on a colony study; this involved sampling honey bees from hives treated and untreated with certain pesticides, then running a battery of biochemical assays, including esterase, glutathione-S-transferase, and acetylcholineesterase, and molecular assays (qPCR of twelve P450, Antioxidant, and Immunity genes). In addition, we continued to assess the risk of mixing fungicides with neonicotinoid insecticides. Although fungicide alone is relatively less toxic to honey bee, it inhibits P450 (the major detoxification enzyme in honey bee). Acute synergistic effect was detected in honey bees treated with mixtures. At the same time, the activities of P450s, as well as the expressions of seven genes (CRBXase, CYP306A1, CYP6AS14, apidaecin, defensing-2, vtg, and gp-93) associated with detoxification metabolism, immune response, development, and endoplasmic reticulum stress, were significantly altered after exposure to fungicide-containing mixtures.
ARS researchers investigated the applicability of an algae-based plant polymer (APP) as a less toxic drift-reducing pesticide adjuvant. Preliminary experiments in the lab and limited field experiments prove its drift reduction potential. Bioassay experiments involving a typical insect pest of soybean and cotton in the region were analyzed to study any antagonistic effects of APP in killing the target pests. Similar bioassay experiments were also carried out with honeybees to analyze the toxicity effects of APP against an industrial standard pesticide adjuvant. The results from all the experiments collectively indicate that the algae-based plant polymer has great potential in mitigating drift as well as minimizing pesticide toxicity to honeybees.
We used herbicide-sensitive plants such as oats and conventional corn in a bioassay-type experiment to understand how far the herbicide drift reaches during ground-based postemergent herbicide applications to cotton. These bioassay plants were grown in pots in a greenhouse under stress-free conditions. Our preliminary results indicate that herbicide drift reaches as far as four swath widths during ground-based postemergence herbicide applications.
We investigated the effects of climate change on pesticide vapor drift using 54 years of past weather data during cotton growth, details on typical pesticide applications and physico-chemical properties of pesticides. Our investigation points out that climate change could bring marginal to moderate increases in the pesticide vapor drift of pesticides applied to cotton.
Our research program focused on investigating bee foraging preferences to better understand their dietary needs - we have collaborations within our unit to assess the interactive effects of clothianidin and nutrition. We also partnered with the USDA Baton Rouge lab to investigate the effects of colony level nutritional stress on bee behavior.
To determine the interactive effects of nutrition and stressors bees experience, we established collaborative projects with labs at Mississippi State University and Auburn University to address questions related to basic bee nutritional ecology and foraging preferences through the pollen phenology project (funds from PAM) and the importance of tallow to honey bees colonies.
We are also studying how agricultural management practices, such as tilling and cover cropping, can affect the soil structure, plant physiology, and resources plants produce for pollinators. We partnered with the Crop Production Systems Research Unit and Auburn University to study these effects. We successfully collected pollen and nectar samples from the experimental plots and will be processing and analyzing them for their nutritional profile.
Accomplishments
1. The health of pollinators, both wild and managed. The health of pollinators, both wild and managed, is of national and international concern. A new ARS research unit focused on Pollinator Health was established in Stoneville, Mississippi, during 2020, and most of the scientific and support positions have been filled. ARS researchers in Stoneville, Mississippi, and new research projects focusing on pollinator health in southern agroecosystems and examining the interactions between bees, agricultural production, and the surrounding landscape are underway.
Review Publications
Venkataraman, K., Kannan, N., Chraibi, V. 2023. Low flow trends in Texas stream segments serving unique hydrologic functions. Texas Water Journal. 14(1):3-33. https://doi.org/10.21423/twj.v14i1.7143.
Zhu, Y., Du, Y., Yao, J., Liu, X.F., Wang, Y. 2023. Detect cytochrome C oxidase- and glutathione-S-transferase-mediated detoxification in a permethrin-resistant population of lygus lineolaris. Toxics. 11(4):342. https://doi.org/10.3390/toxics11040342.
Kannan, N., Anapalli, S.S. 2023. Climate change effects on irrigated corn growth in the Lower Mississippi Delta. Journal of Applied Meteorology and Climatology. 62(3):377-392. https://doi.org/10.1175/JAMC-D-22-0107.1.
Okosun, O.O., George, J., Reddy, G.V. 2023. Role of kairomones in biological control of pests: Commercial potential. In: Koul, O., editor. Development and commercialization of biopesticides: Costs and benefits. London, UK: Academic Press. p. 57-80. https://doi.org/10.1016/B978-0-323-95290-3.00019-4
Lv, L., Li, W., Li, X., Wang, D., Weng, H., Zhu, Y., Wang, Y. 2023. Mixture toxic effects of thiacloprid and cyproconazole on honey bees (Apis mellifera L.). Science of the Total Environment. https://doi.org/10.1016/j.scitotenv.2023.161700.
Li, W., Lv, L., Wang, Y., Zhu, Y. 2023. Mixture effects of thiamethoxam and seven pesticides with different modes of action on honey bees (Aplis mellifera). Scientific Reports. https://www.nature.com/articles/s41598-023-29837-w#article-info.
Anandhi, A., Karunanidhi, D., Muthu, S.G., Panda, S., Kannan, N. 2022. A framework for sustainable groundwater management. Water. 14(21):3416.
Cang, T., Lou, Y., Zhu, Y., Li, W., Weng, H., Lv, L., Wang, Y. 2023. Mixture toxicities of tetrachlorantraniliprole and tebuconazole to honey bees (Apis mellifera L.) and the potential mechanism. Environment International. https://doi.org/10.1016/j.envint.2023.107764.
Wang, D., Lv, L., Gao, Z., Zhu, Y., Weng, H., Yang, G., Wang, Y. 2022. Joint toxic effects of thiamethoxam and flusilazole on the adult worker honey bees (Apis mellifera L.). Journal of Hazardous Materials. https://doi.org/10.1016/j.envpol.2022.120806.
