| 1. |
- Hellstrom, S., et al.
(author)
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Beyond generalists: The Brassicaceae pollen specialist Osmia brevicornis as a prospective model organism when exploring pesticide risk to bees
- 2023
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In: Environmental and Sustainability Indicators. - : Elsevier BV. - 2665-9727. ; 18
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Journal article (peer-reviewed)abstract
- Bees are under threat from agricultural intensification, and species which are pollen specialists (oligolectic) are thought to have declined disproportionately compared to pollen generalists (polylectic). When assessing the risks of dietary pesticide (plant protection products) exposure to non-target beneficial insects such as wild bees, effects on pollen specialist species have seldom been considered. Research and risk assessment on pesticide risk to bees mainly use a small selection of model species, only representing pollen generalist species. Moreover, the foraging preferences of the existing model species are not always adequately matched to the crops investigated, which may lead to incorrect conclusions regarding the risks posed by pesticides in pollen and nectar. Here, we propose Osmia brevicornis, an oligolectic European wild bee species specialized on Brassicaceae pollen, as a new model organism suitable for assessment of how pesticides can impact specialist pollinators, especially in oilseed rape, a mass flowering Brassicaceae crop. We demonstrate that O. brevicornis can be successfully reared in the field next to oilseed rape and that its nesting success and offspring numbers can be increased by setting out a starting population. In our field assay, nesting tube diameter affected occupation rate and the sex ratio of O. brevicornis offspring. We describe a method for housing and controlled oral administration of sucrose solution in the lab-oratory, facilitating future studies on pesticide exposure. We conclude that O. brevicornis is a feasible model for assessing the risk of pesticides in the laboratory and in the field, especially for those compounds used in oilseed rape cultivation, as well as for investigating the general ecology of pollen specialists. By suggesting O. brevicornis as a potential model species, we aim to encourage diversification of the species used in agricultural ecology, especially to consider pollen specialists, and encourage attention to the foraging preferences and dietary needs of selected model species when considering pesticide exposure risk and effects.
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| 2. |
- Osterman, Julia, et al.
(author)
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Mason bees and honey bees synergistically enhance fruit set in sweet cherry orchards
- 2023
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In: Ecology and Evolution. - 2045-7758. ; 13:7
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Journal article (peer-reviewed)abstract
- Mason bees (Osmia spp.) are efficient fruit tree pollinators that can be encouraged to occupy and breed in artificial nesting material. In sweet cherry orchards, they are occasionally used as an alternative managed pollinator as a replacement for or in addition to honey bees (Apis mellifera). Yet, the lack of practical guidelines on management practices, for example optimal stocking rates, for both mason bee nesting material and honey bees might compromise pollination service provision. In this study, we assessed the relationship between stocking rates (honey bee hives and mason bee nesting material) and the abundance of honey bees and mason bees in 17 sweet cherry (Prunus avium) orchards in Central Germany. We furthermore performed a pollination experiment to explore the interactive effect of mason bees and honey bees on sweet cherry fruit set. In the orchards, both honey bee and mason bee abundance increased with increasing stocking rates of hives or nesting material, respectively. Honey bee abundance increased linearly with stocking rates. In contrast, mason bee abundance asymptoted at 2-3 nesting boxes per ha, beyond which more boxes resulted in little increase in visitation rate. Our pollination experiment demonstrated that orchards were pollen limited, with only 28% of insect-pollinated flowers setting fruit versus 39% of optimally hand-pollinated flowers. Honey bees and mason bees enhanced sweet cherry fruit set, but only when both were present and not when either was present alone in an orchard. Our findings demonstrate that offering nesting material for mason bees and employing honey bee hives can enhance bee abundance in sweet cherry orchards. By increasing honey bee abundance in combination with enhanced mason bee abundance, farmers can substantially boost fruit set and potentially sweet cherry yield. To enhance pollination services, farmers should consider the benefits of increasing pollinator biodiversity as an immediate benefit to improve crop yields.
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| 3. |
- Willcox, Bryony K., et al.
(author)
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Emerging threats and opportunities to managed bee species in European agricultural systems: a horizon scan
- 2023
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In: Scientific Reports. - 2045-2322. ; 13
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Journal article (peer-reviewed)abstract
- Managed bee species provide essential pollination services that contribute to food security worldwide. However, managed bees face a diverse array of threats and anticipating these, and potential opportunities to reduce risks, is essential for the sustainable management of pollination services. We conducted a horizon scanning exercise with 20 experts from across Europe to identify emerging threats and opportunities for managed bees in European agricultural systems. An initial 63 issues were identified, and this was shortlisted to 21 issues through the horizon scanning process. These ranged from local landscape-level management to geopolitical issues on a continental and global scale across seven broad themes—Pesticides & pollutants, Technology, Management practices, Predators & parasites, Environmental stressors, Crop modification, and Political & trade influences. While we conducted this horizon scan within a European context, the opportunities and threats identified will likely be relevant to other regions. A renewed research and policy focus, especially on the highest-ranking issues, is required to maximise the value of these opportunities and mitigate threats to maintain sustainable and healthy managed bee pollinators within agricultural systems.
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