Working group ICPBR Assessment of risks posed by guttation

Transcription

1 INTERNATIONAL COMMISSION FOR PLANT-BEE RELATIONSHIPS Bee Protection Group 11 TH INTERNATIONAL SYMPOSIUM HAZARDS OF PESTICIDES TO BEES WAGENINGEN, THE NETHERLANDS November 2-4, 2011 Working group ICPBR Assessment of risks posed by guttation

2 Assessment of risks posed by guttation Members of the working group Jose Anne LORSCH [ joseanne78@yahoo.fr ] Hiroyuki SUZUKI [ suzukih12@sc.sumitomo-chem.co.jp ] Franck MAROLLEAU [franck.marolleau@anses.fr] Christian MAUS [christian.maus@bayer.com ] Jens PISTORIUS [jens.pistorius@jki.bund.de] Johannes LÜCKMANN [johannes.lueckmann@rifcon.de] Rolf FORSTER [rolf.forster@bvl.bund.de] Tricia BROBYN, (CRD) [tricia.brobyn@hse.gsi.gov.uk] Peter CAMPBELL [peter.campbell@syngenta.com] Klaus WALLNER [Klaus.Wallner@uni-hohenheim.de]

3 Problem formulation Photo: Wallner, 2009

4 Problem adressed. Progress achieved. Frequency and Intensity of Guttation of different plants Residue levels Information on the effects on bees Laboratory semi-field field studies Achieved from numerous studies from public research institutes and industry Conclusions on the risk for bees

5 INTERNATIONAL COMMISSION FOR PLANT-BEE RELATIONSHIPS Bee Protection Group 11 TH INTERNATIONAL SYMPOSIUM HAZARDS OF PESTICIDES TO BEES WAGENINGEN, THE NETHERLANDS November 2-4, 2011 Assessment of risks posed by guttation

6 Occurrence of Guttation: Who (which plants). When (time of day, month, year). How much (different plants) Data available for wheat, maize, barley, oilseed rape, oat, carrot, cucumber, aubergine, capsicum, onion, pea, potato, sugar beet, tomato > Occurence, frequency, intensity varies between crops

7 Honey bees need water. Is guttation a relevant water source for honey bees? Water use of honey bees Regulation of air humidity and temperature (cooling) in the hive Need for minerals Dilution of honey from 20 % water to 80 % before feeding, larval food: high water content Water for own use Water sources in surrounding: Rivers, Puddles, ponds.. Dew Condensed water in hive Nectar with high water content water supply for colonies Guttation untreated plants Guttation treated plants

8 uptakte: µl Water Maize. Seed treatment vs Granules. From hazard to risk Uptake of guttation fluids in µl necessary to reach LD 50 0,005 0,01 0,05 0,1 0,5 1 1,5 2 3 a.s. in ng/µl Concentration [ng/µl] Analyses: D. Schenke, JKI-ÖPV Seed treatment Granules Days after emergence >3.7 µl Water consumption at 1 ng a.s/µl: LD ng/bee exceeded.

9 Winter oilseed rape overwintering The amount of residues in guttation droplets depends on: Concentration [ng/µl] Analyses: D. Schenke, JKI-ÖPV the properties of the active substance the amount of active per seed Crop, growth stage and other factors Days after emergence

10 Laboratory feeding studies Laboratory: impossible to create realistic exposure of bees to water with sugar enriched guttation droplets Guttation liquid artificially spiked with sucrose is used as a carbohydrate source and does not represent a realistic exposure scenario of bees to water Fast screening for residues in droplets at different growth stages with feeding tests in cages outcome comparable to OECD 213/214 laboratory toxicity data indicates hazard only > Investigation of risk for bees under semi-field and field conditions

11 Semi field, field studies monitorings Worst case scenarios Potentially risk high Risk factors A.i. Crop, age of crop a.i./seed Alternative water sources Distance of colonies to treated crop Highest water needs Potentially risk low Most Studies conducted are worst case scenarios in Maize Distance: Colonies directly at field edge Maize was identified as the crop most strongly associated with potential risk factors: showing frequently Guttation with high residues at time of highest water needs of bee colonies

12 Semi- field and field trials, maize. from forced to realistic exposure. See poster Frommberger et al. Bees (Treatment without water) suffering thirst in first trial No effects when water was supplied in tents No effects observed in realistic field conditions at the same time and location

13 Outcome of Semi-field studies Semi-field studies are useable to simulate water collection from guttation droplets Bees are forced to use available water sources, e.g. guttation water due to lack of alternative water supply. As conditions can be controlled, e.g. alternative water sources can be excluded, ensuring a maximum of exposure. Semi-field designs are suitable for mechanistic studies Limited potential for extrapolation to field conditions.

14 Field monitoring maize Granules, a.i. Clothianidin LAVES, 2010 LAVES, 2011 LWG Veitshöchstheim, 2010 LWG Veitshöchstheim, 2011 Impact on Mortality Single days with mortality peaks and residues in dead bees no clear mortality peaks Chemical analyses ongoing no clear mortality peaks but residues in dead bees on some days. no clear mortality peaks Chemical analyses ongoing Impact on colony and brood development No effect on colony and brood development. No effect on colony and brood development. No effect on colony and brood development. No effect on colony and brood development.

15 Dead bee/colony/day Monitoring: Granules [a.i.clothianidin] Guttation Dead bees µg/kg Cl. Field monitoring (2010, Bee institute Laves, Celle) with worst case exposure: set-up at field border. Several occasions with guttation of maize but no effects. Single days with clear mortality peaks. No long term effect on colony and brood development. Same set up at Bee institute Veitshöchheim- no clear mortality peaks but residues in dead bees. No long term effect on colony and brood development.

16 Outcome of Monitoring wide range of possible designs to determine potential effects on bee colonies. The significance of the results depends on the design of the study. As the colonies show an individually variable water foraging behavior and the environmental conditions of the study sites may be variable, the intrinsic variability of the systems can be compensated by appropriate replicate (e.g. colony and field) numbers.

17 Are risk mitigation options possible? Who is responsible for risk mitigation? Distance of crop to bees Distance of bees to crop possibility to locate colonies in areas with untreated plants/(un)managed field margins? Provision of water for bees Is mutual information a possible way forward? Which probability of colonies being located near treated fields?

18 Which circumstances/settings may potentially pose a risk in field conditions? Most important: position of the bee hive in relation to the treated crop and alternative water sources in the surrounding occurrence of guttation occurrence of guttation droplets with considerable residue levels Intrinsic properties of product time of bee activity, seasonal activity and seasonal water needs of colonies

19 Summary A large number of studies was conducted by both public research labs and industry crops vary in the intensity and frequency of guttation events residues depend on the properties of the active substance, a.s. per seed and other factors Peak residues in young growth stages guttation droplets are one out of several possible water sources in the surrounding of a colony and only available at a limited time collection of guttation liquid is not an exposure scenario comparable with exposure to nectar and pollen risk is likely to decrease rapidly with distance of the colonies to treated crops and the availability of alternative water sources nearby- mitigation measures possible?

20 Results and conclusions in majority of realistic worst case exposure trials from both research institutes and industry no treatment related mortality peaks were seen Only in certain circumstances some increased mortality observed on single events in some monitorings with maize, when colonies were placed directly next to the crop data indicate damage to colonies in realistic worst case scenarios are on a low level, effects on colony strength, brood development and overwintering have not been observed. in incident reporting schemes of different countries no apparent poisoning incidents linked with guttation were reported and ascertained in the investigation of incidents.

21 Regulatory implications Some crops may need more consideration (e.g. maize), than others (eg. sugar beet) Usually data for toxicity available standard regulatory requirement is not for all actives necessary Data from experiments with intrinsically highly toxic, systemic insecticides indicate that further studies exceeding standard laboratory toxicity data might only be needed for a very limited number of actives. Regulatory decisions by risk assessors on a case by case basis considering systemic properties of a.i. (xylem mobility), persistence, intrinsic toxicity for bees and mode of action

22 Recommendations: Guttation study set-up Available study designs can be used for adressing risk. Some Modifications for semi field-trials and field trials recommended Modifications depending on study aim: Consider location e.g. directly at field edge Time of set-up of colonies at the field Crop stage with highest residues, emergence Prolonged assessment periods (mortality etc.) Consider using extra water sources

23 Many thanks to Thank you! Members of the working group Jose Anne LORSCH, Hiroyuki SUZUKI, Franck MAROLLEAU, Christian MAUS, Jens PISTORIUS, Johannes LÜCKMANN, Rolf FORSTER, Tricia BROBYN, Peter CAMPBELL, Klaus WALLNER Contributors Problem adressed. Progress achieved. Ina Joachimsmeier, D. Schenke, Malte Frommberger, Ingrid Illies, Werner von der Ohe, Stefan Berg A lot of dedicated and patient field staff!

24 Water and the risk for bees in field trials