Bees Could Visit Flower “Pharmacies” When They Are Sick

peer reviewedWhen you are sick, you might go to the pharmacy to get some medicines. But have you ever wondered what do animals do when they are sick? Bees are tremendously important given the roles they play in the environment and human societies. Unfortunately, bees have been declining in the last decades, partly due to infection by parasites. But certain flowers may help them! Bees collect resources from various flowers and, recently, scientists have shown that some of these flower resources could help bees fight infections. Flower resources contain many essential nutrients as well as very specific medicines that could strengthen the bees or kill the parasites. Once sick, bees could prioritize the collection of resources from specific flowers to dealwith their parasites and heal themselves. It is therefore important for us to plant flowers rich in essential nutrients, as well as flowers rich in medicines that help bees to thrive and fight o infections

Ensuring access to high-quality resources reduces the impacts of heat stress on bees

Pollinators are experiencing declines globally, negatively affecting the reproduction of wild plants and crop production. Well-known drivers of these declines include climatic and nutritional stresses, such as a change of dietary resources due to the degradation of habitat quality. Understanding potential synergies between these two important drivers is needed to improve predictive models of the future effects of climate change on pollinator declines. Here, bumblebee colony bioassays were used to evaluate the interactive effects of heat stress, a reduction of dietary resource quality, and colony size. Using a total of 117 colonies, we applied a fully crossed experiment to test the effect of three dietary quality levels under three levels of heat stress with two colony sizes. Both nutritional and heat stress reduced colony development resulting in a lower investment in offspring production. Small colonies were much more sensitive to heat and nutritional stresses than large ones, possibly because a higher percentage of workers helps maintain social homeostasis. Strikingly, the effects of heat stress were far less pronounced for small colonies fed with suitable diets. Overall, our study suggests that landscape management actions that ensure access to high-quality resources could reduce the impacts of heat stress on bee decline.info:eu-repo/semantics/publishedVersio

Behavioral adaptation to polylectism in bees

Sterolic composition of pollen is highly variable among plant species. These compounds are known to be essential for bees as they play important roles in their metabolism such as molting hormone precursors . As they forage on many different plant species, polylectic bees could especially be impacted by this sterolic variability. This work aimed to investigate potential behavioral adaptation of polylectic bees to this variability by adding particular sterols during confection of pollen loads. By contrast, specialist species are expected to be adaptated to their host-plant and would not display such behavior

Invasive plants as potential food resource for native pollinators: A case study with two invasive species and a generalist bumble bee

peer reviewedIt is now well established that invasive plants may induce drifts in the quantity and/or quality of floral resources. They are then often pointed out as a potential driver of bee decline. However, their impact on bee population remains quite unclear and still controversial, as bee responses are highly variable among species. Here, we compared the amino acid composition of pollen from three native and two invasive plant species included in diets of common pollinators in NW Europe. Moreover, the nutritional intake (i.e., pollen and amino acid intakes) of Bombus terrestris colonies and the pollen foraging behaviour of workers (i.e., visiting rate, number of foraging trips, weight of pollen loads) were considered. We found significant differences in pollen nutrients among the studied species according to the plant invasive behaviour. We also found significant differences in pollen foraging behaviour according to the plant species, from few to several foraging trips carrying small or large pollen loads. Such behavioural differences directly impacted the pollen intake but depended more likely on plant morphology rather than on plant invasive behaviour. These results suggest that common generalist bumble bees might not always suffer from plant invasions, depending on their behavioural plasticity and nutritional requirements

Do invaders come in peace? Two invasive species as potential food resources for a generalist bumble bee

Invasive plants are often pointed out as a potential driver of bee decline. However, their impact on bee population remains quite unclear and still controversial. Here, we compared (1) the amino acid composition of pollen from three native and two invasive plant species included in diets of Bombus terrestris, (2) the nutritional intake and (3) the pollen foraging behaviour of workers. We found nutritional and behavioural significant differences among the studied plants. Results of this study suggest that common generalist bumble bees might not always suffer from plant invasions, depending on their behavioural plasticity and nutritional requirements

Pollen as Bee Medicine: Is Prevention Better than Cure?

peer reviewedTo face environmental stressors such as infection, animals may display behavioural plasticity to improve their physiological status through ingestion of specific food. In bees, the significance of medicating pollen may be limited by their ability to exploit it. Until now, studies have focused on the medicinal effects of pollen and nectar after forced-feeding experiments, overlooking spontaneous intake. Here, we explored the medicinal effects of different pollen on Bombus terrestris workers infected by the gut parasite Crithidia bombi. First, we used a forced-feeding experimental design allowing for the distinction between prophylactic and therapeutic effects of pollen, considering host tolerance and resistance. Then, we assessed whether bumble bees favoured medicating resources when infected to demonstrate potential self-medicative behaviour. We found that infected bumble bees had a lower fitness but higher resistance when forced to consume sunflower or heather pollen, and that infection dynamics was more gradual in therapeutic treatments. When given the choice between resources, infected workers did not target medicating pollen, nor did they consume more medicating pollen than uninfected ones. These results emphasize that the access to medicating resources could impede parasite dynamics, but that the cost-benefit trade-off could be detrimental when fitness is highly reduced

Making better food for larvae: do bee females modify sterol composition of pollen loads during foraging

Sterols are essential insect nutrients, involved in some key metabolic pathways. Insects cannot synthesize sterols and must instead draw them from food. For bees, pollen is the only source of sterols, mainly provided in structures with 28 or 29 carbons (i.e., phytosterols). Phytosterol composition of pollen is highly variable among plant species, challenging the physiology and survival of generalist bees. Previous studies have shown that the honey bee (Apis mellifera) is able to handle this variability by adding endogenous sterols to provide a suitable diet to larvae. Such behaviour has never been investigated in other bee species, although it is a key element for understanding bee conservation and evolution. Here, we assessed the sterolic compositions of pollen loads from A. mellifera and compared them to those from generalist (i.e., Bombus terrestris) and wild specialist bee species, as well as to floral pollen. A total of seven plant species from six families and their associated visitors were considered. these results show that some species are able to modify sterol composition of pollen. In some case this modification consist in addition of a peculiar sterol. Moreover this study opens the way to new insights in bee origin and the evolution of their interactions with flowering plants

Sterol addition during pollen collection by bees: another possible strategy to balance nutrient deficiencies?

peer reviewedCaractérisation des propriétés pharmacologiques de plantes mellifères pour les abeilles - Fédération Wallonie Bruxelle

Pollen as Bee Medicine: Is Prevention Better than Cure?

To face environmental stressors such as infection, animals may display behavioural plasticity to improve their physiological status through ingestion of specific food. In bees, the significance of medicating pollen may be limited by their ability to exploit it. Until now, studies have focused on the medicinal effects of pollen and nectar after forcedfeeding experiments, overlooking spontaneous intake. Here, we explored the medicinal effects of different pollen on Bombus terrestris workers infected by the gut parasite Crithidia bombi. First, we used a forced-feeding experimental design allowing for the distinction between prophylactic and therapeutic effects of pollen, considering host tolerance and resistance. Then, we assessed whether bumble bees favoured medicating resources when infected to demonstrate potential self-medicative behaviour. We found that infected bumble bees had a lower fitness but higher resistance when forced to consume sunflower or heather pollen, and that infection dynamics was more gradual in therapeutic treatments. When given the choice between resources, infected workers did not target medicating pollen, nor did they consume more medicating pollen than uninfected ones. These results emphasize that the access to medicating resources could impede parasite dynamics, but that the cost–benefit trade-off could be detrimental when fitness is highly reduced

Generalized host-plant feeding can hide sterol-specialized foraging behaviors in bee-plant interactions

peer reviewe