Flower sharing and pollinator health: a behavioural perspective

This is the author accepted manuscript. The final version is available from the Royal Society via the DOI in this recordDisease is an integral part of any organisms’ life, and bees have evolved immune responses and a suite of hygienic behaviours to keep them at bay in the nest. It is now evident that flowers are another transmission hub for pathogens and parasites, raising questions about adaptations that help pollinating insects stay healthy while visiting hundreds of plants over their lifetime. Drawing on recent advances in our understanding of how bees of varying size, dietary specialisation and sociality differ in their foraging ranges, navigational strategies and floral resource preferences, we explore the behavioural mechanisms and strategies that may enable foraging bees to reduce disease exposure and transmission risks at flowers by partitioning overlapping resources in space and in time. By taking a novel behavioural perspective, we highlight the missing links between disease biology and the ecology of plant-pollinator relationships, critical for improving the understanding of disease transmission risks and the better design and management of habitat for pollinator conservation.Biotechnology & Biological Sciences Research Council (BBSRC)UKRIEuropean Regional Development Fund (ERDF

An update of the Worldwide Integrated Assessment (WIA) on systemic insecticides. Part 2: impacts on organisms and ecosystems

New information on the lethal and sublethal effects of neonicotinoids and fipronil on organisms is presented in this review, complementing the previous WIA in 2015. The high toxicity of these systemic insecticides to invertebrates has been confirmed and expanded to include more species and compounds. Most of the recent research has focused on bees and the sublethal and ecological impacts these insecticides have on pollinators. Toxic effects on other invertebrate taxa also covered predatory and parasitoid natural enemies and aquatic arthropods. Little, while not much new information has been gathered on soil organisms. The impact on marine coastal ecosystems is still largely uncharted. The chronic lethality of neonicotinoids to insects and crustaceans, and the strengthened evidence that these chemicals also impair the immune system and reproduction, highlights the dangers of this particular insecticidal classneonicotinoids and fipronil. , withContinued large scale – mostly prophylactic – use of these persistent organochlorine pesticides has the potential to greatly decreasecompletely eliminate populations of arthropods in both terrestrial and aquatic environments. Sublethal effects on fish, reptiles, frogs, birds and mammals are also reported, showing a better understanding of the mechanisms of toxicity of these insecticides in vertebrates, and their deleterious impacts on growth, reproduction and neurobehaviour of most of the species tested. This review concludes with a summary of impacts on the ecosystem services and functioning, particularly on pollination, soil biota and aquatic invertebrate communities, thus reinforcing the previous WIA conclusions (van der Sluijs et al. 2015)

Multiple stressors interact to impair the performance of bumblebee (Bombus terrestris) colonies

1. Bumblebees are constantly exposed to a wide range of biotic and abiotic stresses which they must defend themselves against to survive. Pathogens and pesticides represent important stressors that influence bumblebee health, both when acting alone or in combination. To better understand bumblebee health, we need to investigate how these factors interact, yet experimental studies to date generally focus on only one or two stressors. 2. The aim of this study is to evaluate how combined effects of four important stressors (the gut parasite Nosema ceranae, the neonicotinoid insecticide thiamethoxam, the pyrethroid insecticide cypermethrin, and the EBI‐fungicide tebuconazole) interact to affect bumblebees at the individual and colony levels. 3. We established seven treatment groups of colonies that we pulse exposed to different combinations of these stressors for two weeks under laboratory conditions. Colonies were subsequently placed in the field for seven weeks to evaluate the effect of treatments on the prevalence of N. ceranae in inoculated bumblebees, expression levels of immunity and detoxification‐related genes, food collection, weight gain, worker and male numbers, and production of worker brood and reproductives. 4. Exposure to pesticide mixtures reduced food collection by bumblebees. All immunity‐related genes were upregulated in the bumblebees inoculated with N. ceranae when they had not been exposed to pesticide mixtures, and bumblebees exposed to the fungicide and the pyrethroid were less likely to have N. ceranae. Combined exposure to the three‐pesticides mixture and N. ceranae reduced bumblebee colony growth, and all treatments had detrimental effects on brood production. The groups exposed to the neonicotinoid insecticide produced 40‐76% fewer queens than control colonies. 5. Our findings show that exposure to combinations of stressors that bumblebees frequently come into contact with have detrimental effects on colony health and performance and could therefore have an impact at the population level. These results also have significant implications for current practices and policies for pesticide risk assessment and use as the combinations tested here are frequently applied simultaneously in the field. Understanding the interactions between different stressors will be crucial for improving our ability to manage bee populations and for ensuring pollination services into the future

List of some key papers that investigated indirect transmission of pathogens in bees through shared use of flowers. from Flower sharing and pollinator health: a behavioural perspective

Main reported results related to route of transmission are indicated. F.S., suggested fecal-oral transmission; O.A., transmission through oral contact with artificially contaminated flowers; O.S.S., suggested oral transmission through contamination of flowers with bee oral secretions; Flw.S., suggested indirect transmission through shared use of flowers, specific route unknown; DWV, deformed wing virus; SBV, sacbrood bee virus; BQCV, black queen cell virus; ABPV, acute bee paralysis virus; IAPV, Israeli acute paralysis virus; KBV, kashmir bee virus; CBPV, chronic bee paralysis virus

Selected studies investigating the role of bees as vectors of plant microbes. from Flower sharing and pollinator health: a behavioural perspective

Some microbes are phytopathogens (tagged with (p))

Flower sharing and pollinator health: a behavioural perspective

Disease is an integral part of any organisms’ life, and bees have evolved immune responses and a suite of hygienic behaviours to keep them at bay in the nest. It is now evident that flowers are another transmission hub for pathogens and parasites, raising questions about adaptations that help pollinating insects stay healthy while visiting hundreds of plants over their lifetime. Drawing on recent advances in our understanding of how bees of varying size, dietary specialisation and sociality differ in their foraging ranges, navigational strategies and floral resource preferences, we explore the behavioural mechanisms and strategies that may enable foraging bees to reduce disease exposure and transmission risks at flowers by partitioning overlapping resources in space and in time. By taking a novel behavioural perspective, we highlight the missing links between disease biology and the ecology of plant-pollinator relationships, critical for improving the understanding of disease transmission risks and the better design and management of habitat for pollinator conservation

Multiple stressors interact to impair the performance of bumblebee (Bombus terrestris) colonies

1. Bumblebees are constantly exposed to a wide range of biotic and abiotic stresses which they must defend themselves against to survive. Pathogens and pesticides represent important stressors that influence bumblebee health, both when acting alone or in combination. To better understand bumblebee health, we need to investigate how these factors interact, yet experimental studies to date generally focus on only one or two stressors. 2. The aim of this study is to evaluate how combined effects of four important stressors (the gut parasite Nosema ceranae, the neonicotinoid insecticide thiamethoxam, the pyrethroid insecticide cypermethrin, and the EBI-fungicide tebuconazole) interact to affect bumblebees at the individual and colony levels. 3. We established seven treatment groups of colonies that we pulse exposed to different combinations of these stressors for two weeks under laboratory conditions. Colonies were subsequently placed in the field for seven weeks to evaluate the effect of treatments on the prevalence of N. ceranae in inoculated bumblebees, expression levels of immunity and detoxification-related genes, food collection, weight gain, worker and male numbers, and production of worker brood and reproductives. 4. Exposure to pesticide mixtures reduced food collection by bumblebees. All immunity-related genes were upregulated in the bumblebees inoculated with N. ceranae when they had not been exposed to pesticide mixtures, and bumblebees exposed to the fungicide and the pyrethroid were less likely to have N. ceranae. Combined exposure to the three-pesticides mixture and N. ceranae reduced bumblebee colony growth, and all treatments had detrimental effects on brood production. The groups exposed to the neonicotinoid insecticide produced 40-76% fewer queens than control colonies. 5. Our findings show that exposure to combinations of stressors that bumblebees frequently come into contact with have detrimental effects on colony health and performance and could therefore have an impact at the population level. These results also have significant implications for current practices and policies for pesticide risk assessment and use as the combinations tested here are frequently applied simultaneously in the field. Understanding the interactions between different stressors will be crucial for improving our ability to manage bee populations and for ensuring pollination services into the future