Neonicotinoid Sunflower Seed Treatment, While Not Detected in Pollen and Nectar, Still Impacts Wild Bees and Crop Yield
Neonicotinoid seed treatments are commonly used in agricultural production even though their benefit to crop yield and their impact on pollinators, particularly wild bees, remains unclear. Using an on-farm matched pair design in which half of each field was sown with thiamethoxam treated seed and ha...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-06-01
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| Series: | Agrochemicals |
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| Online Access: | https://www.mdpi.com/2813-3145/2/2/18 |
| _version_ | 1827739068041003008 |
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| author | Laura T. Ward Michelle L. Hladik Aidee Guzman Ariana Bautista Nicholas J. Mills |
| author_facet | Laura T. Ward Michelle L. Hladik Aidee Guzman Ariana Bautista Nicholas J. Mills |
| author_sort | Laura T. Ward |
| collection | DOAJ |
| description | Neonicotinoid seed treatments are commonly used in agricultural production even though their benefit to crop yield and their impact on pollinators, particularly wild bees, remains unclear. Using an on-farm matched pair design in which half of each field was sown with thiamethoxam treated seed and half without, we assessed honey bee and wild bee exposure to pesticides in sunflower fields by analyzing pesticide residues in field soil, sunflower pollen and nectar, pollen-foraging and nectar-foraging honey bees, and a sunflower specialist wild bee (<i>Melissodes agilis</i>). We also quantified the effects of thiamethoxam-treated seed on wild bee biodiversity and crop yield. <i>M. agilis</i> abundance was significantly lower with thiamethoxam treatment and overall wild bee abundance trending lower but was not significantly different. Furthermore, crop yield was significantly lower in plots with thiamethoxam treatment, even though thiamethoxam was only detected at low concentrations in one soil sample (and its primary metabolite, clothianidin, was never detected). Conversely, wild bee richness was significantly higher and diversity was marginally higher with thiamethoxam treatment. Nectar volumes harvested from the nectar-foraging honey bees were also significantly higher with thiamethoxam treatment. Several pesticides that were not used in the sunflower fields were detected in our samples, some of which are known to be deleterious to bee health, highlighting the importance of the landscape scale in the assessment of pesticide exposure for bees. Overall, our results suggest that thiamethoxam seed treatments may negatively impact wild bee pollination services in sunflower. Importantly, this study highlights the advantages of the inclusion of other metrics, such as biodiversity or behavior, in pesticide risk analysis, as pesticide residue analysis, as an independent metric, may erroneously miss the impacts of field realistic pesticide exposure on bees. |
| first_indexed | 2024-03-11T02:52:53Z |
| format | Article |
| id | doaj.art-791f1c335395406c998871da9b10f11b |
| institution | Directory Open Access Journal |
| issn | 2813-3145 |
| language | English |
| last_indexed | 2024-03-11T02:52:53Z |
| publishDate | 2023-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Agrochemicals |
| spelling | doaj.art-791f1c335395406c998871da9b10f11b2023-11-18T08:53:11ZengMDPI AGAgrochemicals2813-31452023-06-012227929510.3390/agrochemicals2020018Neonicotinoid Sunflower Seed Treatment, While Not Detected in Pollen and Nectar, Still Impacts Wild Bees and Crop YieldLaura T. Ward0Michelle L. Hladik1Aidee Guzman2Ariana Bautista3Nicholas J. Mills4Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720-3114, USAU.S. Geological Survey, California Water Science Center, Sacramento, CA 95819, USADepartment of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720-3114, USADepartment of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720-3114, USADepartment of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720-3114, USANeonicotinoid seed treatments are commonly used in agricultural production even though their benefit to crop yield and their impact on pollinators, particularly wild bees, remains unclear. Using an on-farm matched pair design in which half of each field was sown with thiamethoxam treated seed and half without, we assessed honey bee and wild bee exposure to pesticides in sunflower fields by analyzing pesticide residues in field soil, sunflower pollen and nectar, pollen-foraging and nectar-foraging honey bees, and a sunflower specialist wild bee (<i>Melissodes agilis</i>). We also quantified the effects of thiamethoxam-treated seed on wild bee biodiversity and crop yield. <i>M. agilis</i> abundance was significantly lower with thiamethoxam treatment and overall wild bee abundance trending lower but was not significantly different. Furthermore, crop yield was significantly lower in plots with thiamethoxam treatment, even though thiamethoxam was only detected at low concentrations in one soil sample (and its primary metabolite, clothianidin, was never detected). Conversely, wild bee richness was significantly higher and diversity was marginally higher with thiamethoxam treatment. Nectar volumes harvested from the nectar-foraging honey bees were also significantly higher with thiamethoxam treatment. Several pesticides that were not used in the sunflower fields were detected in our samples, some of which are known to be deleterious to bee health, highlighting the importance of the landscape scale in the assessment of pesticide exposure for bees. Overall, our results suggest that thiamethoxam seed treatments may negatively impact wild bee pollination services in sunflower. Importantly, this study highlights the advantages of the inclusion of other metrics, such as biodiversity or behavior, in pesticide risk analysis, as pesticide residue analysis, as an independent metric, may erroneously miss the impacts of field realistic pesticide exposure on bees.https://www.mdpi.com/2813-3145/2/2/18honey bees<i>Melissodes agilis</i>herbicideinsecticidefungicidethiamethoxam |
| spellingShingle | Laura T. Ward Michelle L. Hladik Aidee Guzman Ariana Bautista Nicholas J. Mills Neonicotinoid Sunflower Seed Treatment, While Not Detected in Pollen and Nectar, Still Impacts Wild Bees and Crop Yield Agrochemicals honey bees <i>Melissodes agilis</i> herbicide insecticide fungicide thiamethoxam |
| title | Neonicotinoid Sunflower Seed Treatment, While Not Detected in Pollen and Nectar, Still Impacts Wild Bees and Crop Yield |
| title_full | Neonicotinoid Sunflower Seed Treatment, While Not Detected in Pollen and Nectar, Still Impacts Wild Bees and Crop Yield |
| title_fullStr | Neonicotinoid Sunflower Seed Treatment, While Not Detected in Pollen and Nectar, Still Impacts Wild Bees and Crop Yield |
| title_full_unstemmed | Neonicotinoid Sunflower Seed Treatment, While Not Detected in Pollen and Nectar, Still Impacts Wild Bees and Crop Yield |
| title_short | Neonicotinoid Sunflower Seed Treatment, While Not Detected in Pollen and Nectar, Still Impacts Wild Bees and Crop Yield |
| title_sort | neonicotinoid sunflower seed treatment while not detected in pollen and nectar still impacts wild bees and crop yield |
| topic | honey bees <i>Melissodes agilis</i> herbicide insecticide fungicide thiamethoxam |
| url | https://www.mdpi.com/2813-3145/2/2/18 |
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