Neonicotinoids and bees: an overview on concentrations, side effects and risk assessment

Transcription

1 Neonicotinoids and bees: an overview on concentrations, side effects and risk assessment Tjeerd Blacquière, Guy Smagghe, Kees van Gestel & Veerle Mommaerts

2 Neonicotinoids and bees Introduction: bee mortalities Neonicotinoids + bees: since 1992 > 100 PR papers chemicals & mode of application exposure routes bees residues in plants residues in bee hives and products toxicity to bees (lab & field) acute toxicity (contact & oral) chronic toxicity sub-lethal toxicity

3 Neonicotinoids and bees Neonicotinoids (ctnd) calculated oral exposure comparison with tox data lab & field testing & monitor studies comparison Risk assessment scheme Perspectives

4 Colony losses and bee decline: causes & public concern Many causes: all pollinators: habitat loss (nesting, forage) globalization & invasive species (incl. diseases) climate change pollution & pesticides honey bees: parasitic mite (varroa destructor); invasive, host shifted diseases (many, incl. invasives), some vectored by Varroa beekeeping practices (& a lack of incentives) lack of forage (diversity) synergisms (pesticides/diseases/food/...)

5 Neonicotinoids act systemic Systemic nature determines application spraying soil drench + irrigation (greenhouses) seed coating soaking of flower bulbs pre planting/ prestorage Application implies possible exposure acute topical spray, dust, plant surface oral: water puddles, surface water, guttation oral: food: nectar + honey dew pollen (propolis, resins)

6 Residues Parent chemicals: imidacloprid clothianidin thiametoxam dinotefuran nitenpyram acetamiprid thiacloprid flonicamid Toxicity: LD 50 (contact ; oral) 4-80 ng/bee 44; 3.8 ng/bee 24; 5 ng/bee 75; 23 ng/bee 138; / ng/bee 8090; ng/bee ; ng/bee 51.1; 53.3 mg/bee + metabolites Nitro Cyano

7 Residues found in environment guttation fluid high conc. (mg/l range) Nectar 0-10 µg/l range Pollen 0-10 µg/l range? resins (propolis) surface water no PR data (Visser) Too few species pollen & nectar extrapolation possible? application! near LOD ample data in registration studies? make available!

8 Residues 2 In bee hive? pollen trapped at entrance stored pollen bee bread nectar honey wax on bees Residues found few samples 0-10 µg/kg (some higher mg/kg) many other chemicals insecticides fungicides (many) acaricides (bee keeper) antibiotics (bee keeper) conc s on bees low conc s in wax low

9 Toxicity testing Mortality: acute contact LD 50 acute oral LD 50 chronic (oral) sub-lethal contact oral both acute & chronic sub-lethal effects: Behaviour: PER assay mobility/locomotor activity return flights feeder Reproduction Disease resistance Over wintering individual colony laboratory field

10 Estimating Oral exposure (nectar & pollen) Exposure depends on: concentration residues amount food consumed variable with age and function nectar: high in nectar foragers pollen: high in nurses TER: tox/exp ratio LD 50 / expected dose TER < 10: risk field test needed imidacloprid, nectar sunflower: TER > 6 clothianidin, nectar canola: TER > 5.6 all other cases (chemicals, source) TER > 10 Rortais et al 2005

11 Laboratory & Field testing Laboratory tests: sub-lethal effects from 1.25 ng/bee avoidance repellency overestimation / underestimation artifacts? feed back mechanisms Field tests: no effects at 5 µg/kg field realistic conc s realistic durations time lags slow chronic effects

12 Monitoring studies France, USA+Ca; Germany; Spain Residues Bee health issues Food Colony mortality Correlations no correlations mortality / neonicotinoids found many other residues often < LOD correlations other factors: yes

13 Risk Assessment scheme OEPP/EPPO TER < 10: field testing lack of data residues few plant species near LOD extrapolation? dosage + application soaking flower bulbs more data needed: generate make available (publish registration studies) Field testing scale & power (Creswell 2010) field realistic conc s standardize: mini colonies Bumble bees(mommaerts) mini colonies honey bees

14 Conclusion neonicotinoids: useful tool risks can be assessed well no strong evidence for role in colony losses Nevertheless: data gaps need for good field studies

15 Perspectives & future research aims safer neonicotinoids less persistant selective different nachreceptors sub-lethal effects: better ways to tackle & validate behaviour, foraging mini colonies individual bees followed in hive task succession of bees topics: mixture toxicities fungicides synergisms (f.i. diseases) lab / field lab + field

16 Thank you! Wageningen UR