PREVALENCE OF NOSEMA SPEC. IN NORTH, MIDDLE, AND SOUTHERN EUROPE AND INTERACTIONS AMONG MULTIPLE PRESSURES ON HONEY BEE HEALTH
Peter Rosenkranz, Richard Odemer, Tanja Harsch, Anna Larue, Gina Tanner, Cynthia McDonnell, Didier Crauser, Geoffry Williams, Yves Le Conte, Peter Neumann, Eva Forsgren, Ingemar Fries
Apimondia Buenos Aires 2011 1 Part of the EU project „BEEDOC“, focusing on: 1. Nosema Monitoring 2. Effect of Nosema infection on the colony level . Nosema alone . Combination effects: . Nosema + Pesticide . (Nosema + Varroa) . (Nosema + Virus)
Apimondia Buenos Aires 2011 2 Nosema surveillance
1. Northern/ Middle/ Southern Europe 2. 5 European countries 3. 50-60 colonies at 10-15 apiaries in each country
Apimondia Buenos Aires 2011 3 Sampling procedure Monthly samples from April - October Approx. 100 bees from the first populated comb in the honey super
Apimondia Buenos Aires 2011 4 Nosema Spore quantification • Double walled extraction bag 1 2 • 60 bees filled up with 15 ml water • Crushed and checked for Nosema • Spores counted in haemocytometer • Species identification by PCR 3 4
5
Apimondia Buenos Aires 2011 5 Results: Nosema prevalence in Northern Europe
Sweden Norway
100 100 ] ] 80 80 % % [ [ Mixed Inefction
Mixed Inefction s s e e N. apis i i N. apis n n o o l l 60 60 o o c c
e e v v i i t t i i s s o o 40 40 p p
a a m m e e s s o o 20 20 N N
0 0 Apr 11 Mai 11 Jun 11 Jul 11 Aug 11 Sep 11 Okt 11 Apr 11 Mai 11 Jun 11 Jul 11 Aug 11 Sep 11 Okt 11
Apimondia Buenos Aires 2011 6 Results: Nosema prevalence in Mid-Europe Southern Germany Exclusively Nosema ceranae! 100 (one case of mixed infection) ]
% 80 [
s e i n o l 60 o c
e v i t i
s 40 o p
a m
e 20 s o N
0
0 0 1 1 0 0 10 1 10 1 1 1 1 1 1 r 1 1 0 1 1 1 r 1 1 0 0 2 g p / b 0 0 0 p 2 2 u e 0 e 2 p 2 2 A y e ly A S 1 F h A y e a n u 0 c a n M u J 2 r M u J r a J te M in W Apimondia Buenos Aires 2011 7 Results: Nosema prevalence in Mid-Europe Switzerland 100 Species identication not done yet Mainly Nosema ceranae expected 80 ] % [
s e i n o
l 60 o c
e v i t i s
o 40 p
a m e s o
N 20
0 Oct 2010 Winter Winter Apr 11 May 2011 June 2011 2010/11(2) 2010/11(2)
Apimondia Buenos Aires 2011 8 Results: Nosema prevalence in Southern Europe 100 Southern France
Species identication not done yet
] 80
% Mainly Nosema ceranae expected [
s e i n o l 60 o c
e v i t i s
o 40 p
a m e s
o 20 N
0 June 2010 July 2010 Aug 10 Oct 2010 May 2011 June 2011 July 2011
Apimondia Buenos Aires 2011 9 What about infection rates (No. of spores per bee)?
Apimondia Buenos Aires 2011 10 Southern Germany 2011
Apimondia Buenos Aires 2011 11 Infection rates Average no. of spores per bee
Southern Germany
100 Prevalence
Proportion of infested colonies 80 ] % [
s e i n
o 60 l o c
e v i t i s
o 40 p
a m e s o
N 20
0 Winter 2010/11 Feb 11 March 2011 Apr 11 May 2011 June 2011
Apimondia Buenos Aires 2011 12 Preliminary summary of Nosema surveillance
1. No clinical symptoms reported! 2. 75% of the colonies (Germany & Sweden: 100%) were infested at least once during the monitoring period obviously, there hardly exist “Nosema free” colonies within the European honey bee population. 3. The maximum infestation rate within one colony reached appr. 30 Mio spores per bee (Germany) but less than 10% of the so far analyzed colonies had more than 1 Mio spores per bee. 4. There is no clear seasonal pattern visible, however there is a tendency of higher prevalence and higher infection rates in spring. 5. Nosema apis was primarily found in the Northern parts of Europe.
Our survey did not support the hypothesis that Nosemosis is currently a major threat to honey bees in Europe
Apimondia Buenos Aires 2011 13 Effect of Nosema infections at the colony level
Apimondia Buenos Aires 2011 14 Setup of experimental colonies (providing bees for further experiments)
20 colonies were established through artificial swarms and divided into 4 experimental groups
Apimondia Buenos Aires 2011 15 Apistan Control Apistan + Thiacloprid Thiacloprid
Bees infected with Nosema (+ Varroa, + Virus)
Apimondia Buenos Aires 2011 16 Thiacloprid Control • Neonicotinoid Thiacloprid • Low bee toxicity:
Acute 48 hour LD50 17.32 μg per bee • Registered as “non toxic to bees” in several EU countries used in flowering canola contamination of nectar and pollen
Apimondia Buenos Aires 2011 17 Control Thiacloprid Feeding of 60.000 N. ceranae spores to freshly hatched bees Untreated colonies Pesticide treatment for 2 months
1. Untreated control 3. Treated with Thiacloprid 2. Treated with Nosema 4. Treated with Nosema & Thiacloprid
Introduction of 120 bees per group to observation hives (4 replicates)
Apimondia Buenos Aires 2011 18 Parameters analyzed
. Longevity . Behavior (2x per day ~ 30 minutes per hive): - No. of social contacts (trophallaxis, grooming, feeding) - No. of flights (with/without pollen) . Nosema infection (10 bees at day 15 and at ~ day 30)
Apimondia Buenos Aires 2011 19 Results Infection rates of bees at the end of the experiment
Bees from the “Nosema group”: ~ 4.7 Mio. spores per bee Bees from the “Nosema & Thiacloprid” group: ~ 7.3 Mio. Spores per bee [no significant difference between both groups: p= 0.36 (U-test)]
~ 30% of the bees from the “Control group” were infected with Nosema, most of them with < 500.000 spores per bee
Apimondia Buenos Aires 2011 20 Results: Lifespan of bees from the 4 groups
120 N 100 T
s 80 e C ontrol e b
60 f
o T & N
. 40 o N 20 0 06. 07.07. 08. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 1. 2. J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul Aug . Aug . 120 T & N 100 C ontrol
s 80 N e e b
60 T f o
. 40 o N 20 0 07.07. 08. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 1. 2. 3. 4. J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul J ul Aug . Aug . Aug . Aug .
Apimondia Buenos Aires 2011 21 Additional experiment on synergistic effects: Feeding bees with Nosema spores and feed the observation hive continuously with sugar solution containing 1 ppm Thiacloprid
100 Nos ema & T hiacloprid 80 s e
e 60 C ontrol & T hiacloprid b
f o
. 40 o N 20
0 15.8 20.8 25.8 30.8 4.9 9.9 14.9
Apimondia Buenos Aires 2011 22 Combined effect of Nosema ceranae infection & pesticide treatment on honey bees 1. No measurable effect of Nosema ceranae infestation on longevity of worker bees in observation hives 2. No measurable effect of Nosema ceranae infestation on social behavior, i.e. trophallaxis, flight activity, pollen foraging 3. No measurable effect of additional thiacloprid treatment on Nosema infested bees. Our results in observation hives and mini hives (not presented here) are in contrast to some reports from Southern Europe, both in cage experiments and in free flying colonies
Apimondia Buenos Aires 2011 23 Thank you
Apimondia Buenos Aires 2011 24