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Exploring the world of honeybees and bumblebees

Exploring the world of honeybees and bumblebees. Dr Juliet Osborne Dept of Plant & Invertebrate Ecology Rothamsted Research Harpenden, UK. Rothamsted Research. The world’s oldest agricultural research institute ensuring enhanced and environmentally sustainable crop production.

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Exploring the world of honeybees and bumblebees

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  1. Exploring the world ofhoneybees and bumblebees Dr Juliet Osborne Dept of Plant & Invertebrate Ecology Rothamsted Research Harpenden, UK

  2. Rothamsted Research The world’s oldest agricultural research institute ensuring enhanced and environmentally sustainable crop production

  3. Bee & pollination ecology at Rothamsted • Aims: To protect and promote: • Honeybee & wild bee populations • Crop & wild flower pollination Bee ecology & movement Pollination of crops and wild plants How agriculture affects bee populations

  4. Pollination by bees • For humans: 87 of world crop species require bee pollination: representing 35% of global food production (Klein et al 2007) • Wild plant pollination • Birds & other wildlife rely on seed and fruit Tree fruit Soft fruit Salad Oil seeds Protein Insects Birds Mammals

  5. Talk outline Different bee species essential for pollinating different plants Bumblebee on raspberry Honeybee on oilseed rape Commercial bumblebees • Honeybee decline …..and possible explanations • Bumblebee decline …..and possible explanations • The research: why study bee movement? Commercial bumblebees

  6. Global trends: honeybees & insect-pollinated crops Trends from 1961 to 2006 A) change in no. hives B) change in crop production Aizen et al (2009) Current Biology

  7. National trends in domesticated honeybee stocks Declines may be economically or politically driven Current major honey exporters Trends vary in Europe Aizen et al (2009) Current Biology

  8. What are the causes of honeybee declines? • Not necessarily biological: can be economic and political • Different causes in different countries • Expert view is that losses are caused by combinationof factors • Varroamites & associated viruses are very important • Need more evidence of colony level effects of food availability, sublethal effects of pesticides and interactions with disease. Are honeybee colonies reaching a threshold for collapse based on a combination of factors? We are building models to explore and predict the effects of interactions between in-hive & landscape factors on bee colony strength

  9. Bumblebees in decline in the UK No. b’bee species per 50x50km Before 1960 After 1960 In the UK, ranges of many Bombus species have shrunk Williams & Osborne (2009)

  10. About 69 species in the Europe (1 honeybee) Bumblebees have annual colonies - need undisturbed nest sites - only 50-200 bees in colony (h’bees have 60,000) They don’t make honey - need continual succession of flowers - not managed in hives No varroa mite; but have other diseases – not as well studied as honeybees Forage in cooler conditions Much better at pollinating tomatoes, peppers, beans, clover Comparing bumblebees with honeybees

  11. Commercialcolonies? Nest sites Nectar & pollen X Predation? Disease? Farming What is affecting bumblebee populations?

  12. Effects of agri-environment schemes The “Big Bee project Farmers sow wild flower mixtures as part of agri-environment schemes Mixture contains red clover, white clover & birdsfoot trefoil What effect does the area of sown wild flower margin have on bumblebee populations? • Growing on intensive arable farms boosts bumblebee density more • Size doesn’t matter: 0.25 Ha plots were as effective as 1 Ha plots Heard et al 2009; Carvell et al (in press)

  13. Talk outline • Bees and Pollination • Honeybee decline & possible explanations • Bumblebee decline & possible explanations • The research: why studying bee movement is important • Bees must find flowers in a very fragmented landscape …and fly home again • Colony survival affected by energy and time spent searching for flowers, and flying to forage • Predation, pesticide exposure and pollen movement influenced by foraging range Commercial bumblebees

  14. How bees move around the landscape quantity quality distance How do bees find nectar & pollen sources? How far do they travel? What is the impact on the colony?

  15. Tracking bee movement with harmonic radar Harmonic radar Honeybee, with radar transponder (aerial) • Produces geometrically accurate maps of insect flight • Transponder is 16mm long and requires no battery • range: horizontal 1 km, vertical 5 m Riley et al 1996

  16. How do bees explore and find food? • Always see looped patterns • Use to predict which flower patches will be used in different landscapes • Can build into mathematical models Searching – feeder removed Bumblebee searching on first flight Reynolds et al J Exp Biol (2007; 2009)

  17. Where do bumblebees go? flowering crops hedgerows Flights of bumblebees leaving a colony Most bees flew over 250m Mean flight speed = 15.6 mph O 200m = bee flight path = colony position O Osborne et al, (1999); Riley et al (1999)

  18. How bees move around the landscape quantity quality distance How do bees find nectar & pollen sources? How far do they travel? What is the impact on the colony?

  19. Where do honeybees go: de-coding the dance Plotted locations of foraging bees De-coding dances at observation hives

  20. Distribution of honeybees on oilseed rape • Placed 18 colonies on a 1.3 km transect across Rothamsted farm. • Powder dye added to each colony (one colour per site) • Scored number of marked bees on 5 oilseed rape fields

  21. Distribution of honeybees on oilseed rape • 736 marked bees were seen (constituted 67% of foraging bees) • Most bees were on nearest field to their hives • Bees foraged further from colonies as flowers dropped Proportions of bees of each colour observed, by field

  22. X X X X X X X X X X 2km 2km Comparing foraging ranges between bee species 2km earth bumblebee 5km honeybees 500m common carder bumblebee X X X X X 2km • Foraging range affects bee survival via food intake; but also risks of predation and exposure to pesticides • Foraging range will affect pollen movement between crop fields

  23. What next? Honeybees and bumblebees are in decline in Europe Need better records of trends: not just overwinter mortality Pathogens and pests: Target new Varroa control methods Target beekeeping practices….education Poor nutrition & nesting sites: Targeted agri-environment schemes work – grow legumes! Target habitats: Arable, grassland, urban Pesticides: More evidence required on sublethal effects & interactions Encourage farmer / beekeeper interactions Think about domestic horticulture?

  24. Acknowledgements Rothamstedbee team Funders BBSRC Defra CB Dennis Trust Game & Wildlife Conservancy Trust Syngenta Collaborators Prof Lars Chittka Prof Rob Paxton Prof Dave Goulson - Stirling Dr Claire Carvell – CEH Dr Dave Chandler – Warwick http://www.rothamsted.bbsrc.ac.uk/pie/JulietOsborne.html

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