Transcript Sunflower

Bee Safety of Imidacloprid
Seed Treatment
to Sunflower
J. Keppler, Ch. Maus, R. Schmuck,
A. Nikolakis, T. Schneider
1. Exposure of honey bees to
Imidacloprid (seed treatment)
 Plant metabolism
 Residues in bee-relevant matrices
Imidacloprid Seed-Dressing Sunflower: Bee Safety 02.07.2008
Uptake and translocation rate
The metabolism studies resulted as follows:
The overall uptake of seed dressed
imidacloprid (incl. other soil applications)
into plants is between 1.6 and 4.9 %
Imidacloprid Seed-Dressing Sunflower: Bee Safety 02.07.2008
Systemicity Principle
As the mobility of imidacloprid in the xylem
is high, the acropetal translocation to shoots
and leaves is good (systemicity). The highest
imidacloprid concentrations in plants are
found in the oldest leaves.
The translocation of imidacloprid and its
metabolites via the phloem (basipetal
translocation) to e. g. storage organs, roots,
and fruits is low.
Imidacloprid Seed-Dressing Sunflower: Bee Safety 02.07.2008
Discussion of bee-relevant metabolites
Bee relevant metabolites were not detected in bee-relevant matrices
(pollen and/or nectar) after seed-dressing applications of relevant
crop cultures.
Nevertheless, the bee relevant metabolites were included in the
analytical method for residue studies precautionary.
Imidacloprid Seed-Dressing Sunflower: Bee Safety 02.07.2008
Residue levels in bee-relevant plant matrices
Maximum residue levels of imidacloprid detected in respective plant
matrices in the field
Imidacloprid
Sunflower Nectar
Sunflower Pollen
> 4 studies
> 4studies
n.d.
n.d.
LOQ Imidacloprid: 5 ppb
LOD Imidacloprid: 1.5 ppb
n.d.: not detectable; < LOD
Conclusion: residues in bee-relevant
matrices of sunflowers never found
Imidacloprid Seed-Dressing Sunflower: Bee Safety 02.07.2008
Residue levels in nectar and pollen
Field residue levels of bee-relevant imidacloprid metabolites
Hydroxy –Imidacloprid
Olefine-Imidacloprid
Sunflower Nectar
Sunflower Pollen
n.d.
n.d.
n.d.
n.d.
Hydroxy-Imidacloprid: LOQ 5 ppb; LOD 1.5 ppb
Olefine-Imidacloprid: LOQ 10 ppb; LOD 3.0 ppb
n.d.: not detectable;
< LOD
Conclusion: bee-relevant metabolites not
detectable
Imidacloprid Seed-Dressing Sunflower: Bee Safety 02.07.2008
Succeeding crops – soil residues
 Imidacloprid should protect seeds and plants during the growth
phase, rendering the repeated use of plant protectants superfluous.
 A certain degree of stability (persistence) for the a. i. in the soil is
therefore necessary.
 Residual amounts of imidacloprid in soil become more and more
firmly attached to the soil matrix through natural binding
processes.
 Aged soil residues of imidacloprid are therefore less biologically
available and do not pose a risk to the environment.
 Numerous studies by independent experts and BCS reveal that
imidacloprid is continuously degraded by microbes and is
ineffective in the following agricultural cultivation period.
Bayer CropScience AG (2002): Environmental fate of imidacloprid, Pflanzenschutznachrichten Bayer,
Vol. 55, Special edition)
Imidacloprid Seed-Dressing Sunflower: Bee Safety 02.07.2008
Accumulation
Trials over several years – long term dissipation studies with
repetitive applications – confirmed that imidacloprid does not
accumulate in soil.
Bayer CropScience AG (2002): Environmental fate of imidacloprid, Pflanzenschutznachrichten Bayer,
Vol. 55, Special edition)
Imidacloprid Seed-Dressing Sunflower: Bee Safety 02.07.2008
2. Effects of Imidacloprid (seed
treatment) on honey-bees
 Acute effects (laboratory)
 Chronic effects (laboratory)
 Tunnel & field studies
Imidacloprid Seed-Dressing Sunflower: Bee Safety 02.07.2008
Intrinsic acute bee toxicity
Imidacloprid
 Regulatory LD50 (oral): 3.7 ng/bee
 NOEC: 42 ppb
 LD50 (contact): 42.9 ng/bee or greater
Imidacloprid Seed-Dressing Sunflower: Bee Safety 02.07.2008
Acute sublethal effects
 Lowest NOEC in reliable olfactory
conditioning test: 50 ppb.
 No or less pronounced effects for
metabolites.
BCS conclusion:
 No acute sublethal effects e. g. on
learning behaviour of bees at acute
dietary NOEC of 42 ppb.
Imidacloprid Seed-Dressing Sunflower: Bee Safety 02.07.2008
Chronic lethal effects
 Reliable laboratory studies showed no increased mortality after
chronic exposure to dietary concentrations of 10 ppb or lower.
However, no increased mortality was found for > 20 ppb under
more realistic exposure conditions (tunnel or field studies).
Imidacloprid Seed-Dressing Sunflower: Bee Safety 02.07.2008
Chronic sublethal effects
 No chronic mortality and no anti-feedant effects < 20 ppb
 Hive development not adversely affected
at concentrations < 20 ppb
 No loss of foraging bees at < 100 ppb
BCS conclusion:
 NOAEC under field conditions > 20 ppb
Imidacloprid Seed-Dressing Sunflower: Bee Safety 02.07.2008
Effect threshold under field conditions
Under field conditions no adverse effects (NOAEC) at 20 ppb
 No acute or chronic mortality
 No adverse effects on colony strength and brood development
 No losses of foraging bees due to impacts on orientation
Imidacloprid Seed-Dressing Sunflower: Bee Safety 02.07.2008
Field-relevant NOAEC value
20 ppb is considered a field-relevant NOAEC since
 No chronic mortality occurred at < 20 ppb
 No anti-feedant responses occurred at < 20 ppb
 Hive performance was not impaired at < 20 ppb
 No loss of foraging bees was observed at < 100 ppb
Imidacloprid Seed-Dressing Sunflower: Bee Safety 02.07.2008
Conclusion on higher tier studies
 The field relevant NOAEC is > 20 ppb.
Imidacloprid Seed-Dressing Sunflower: Bee Safety 02.07.2008
Risk assessment
Comparison of maximum exposure and NOAEC
Imidacloprid residue level detected
in the field in relevant matrices of sunflower:
< LOD (= 1.5 ppb)
NOAEC under field conditions: > 20 ppb
 Negligible Risk to Honeybees
* 1 ppb = 1 part per billion
= 1 µg / kg
= 0.000 000 1 %
Imidacloprid Seed-Dressing Sunflower: Bee Safety 02.07.2008
18 International tunnel studies
Various
- Countries
- Climates
- Soils
- Bee colonies
- Colony sizes
Cultures
- Sunflower
- Summer rape
- Winter rape
- Phacelia
- Maize
BCS-France
Sunflower
1995
Bayer CropScience studies
3x
external studies
2x
BCS-GB/Sweden BCS-Germany
Summer rape
Summer rape
3x
3x
BCS-GB/Sweden BCS-Germany
Sunflower
Sunflower
Hohenheim- AgView, Canada
Germany,Phacelia
Rape
BCS-France ACTA, France BBA, Germany
Sunflower
Sunflower
Rape
1996
1997
1998
1999
BCS-Germany
Mais
2000
No effect on bees in 18 tunnel studies
Imidacloprid Seed-Dressing Sunflower: Bee Safety 02.07.2008
2001
14 International field studies
Various
- Countries
- Climates
- Soils
- Bee colonies
- Colony sizes
Cultures
- Sunflower
- Summer rape
- Winter rape
- Phacelia
- Maize
BCS-France
Sunflower
1995
Bayer CropScience studies
external studies
CNEVA, France
Sunflower
Facanc., Hung Uni Minnes., USA
Sunflower
Rape
ACTA, France
Sunflower
ACTA, France BCS-Germany Celle, Ger Uni Guelph, CAN
Sunflower
Sunflower
Rape
Rape
BCS-France ACTA, France Mayen, Ger Mayen, Ger
Sunflower
Sunflower
Sunflower
Sunflower
1996
1997
1998/1
1998/2
1999
No effect on bees in 14 field studies
Imidacloprid Seed-Dressing Sunflower: Bee Safety 02.07.2008
CONICET, ARG
Sunflower
2000
Thank you very much for
your kind attention!
Imidacloprid Seed-Dressing Sunflower: Bee Safety 02.07.2008