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Comparativa en virulencia y temperatura nosema
Citation preview
Comparative virulence and temperature preferences in
Nosema apis and Nosema ceranae
Ingemar Fries, Eva Forsgren, Department of Ecology
Swedish Univdersity of Agricultural Sciences75007 Uppsala, Sweden
Apimondia, Buenos Aires, September 2011
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Background
Two microsporidia infections are described from the European honey bee:
Nosema apis, isolated from bees in Europe (Zander, 1907)
Nosema ceranae isolated from Apis cerana in China (Fries et al., 1996)
In 2005 Nosema ceranae wasfound as natural infections inhoney bees in Europe (Higes et al,2005) And from Taiwan (Huan et al.,2005)
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Nosema ceranae resembles Nosema apis
Similar life cycles. Only the epithelial cells of the ventriculus become infected
From Fries et al., 2007
Both belong to the Nosematidae family- no sexual reproduction and disporoblasticdevelopment
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Although similar, certain features are different
Spores are smaller and less uniform in LM
From
Frie
s et
al.,
200
7
Number of filament coils are always lower in N. ceranae compared to N.apis
www.bee-doc.eu
One characteristic of N. ceranae in A. cerana is the lack of emptiedspores in the host epithelium
In A. mellifera, however, emptied spores of N. ceranae is found(Higes et al., 2006)
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Ventricular epithelium five days p.i.
Gut lumen
Merozoites
In N. apis you alwaysfind emptied spores when mature spores are present
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There seems to be a correlation between the incidenceof Microsporidia infections in Spain and the detection ofN. ceranae in Spanish bees (Highes et al., 2006). In Italy beelosses are also linked to Microsporidia lately (Nanetti, 2008, pers. info)
Data from Spain (Higes et al., 2008) suggest a close relationship betweencolony collapse and N. ceranae. However, this is not evident from the US (Cox-Foster et al., 2007), nor from northern Europe (Gisder et al., 2010).
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From Klee et al., 2007
Pre-2003
Nosema apis own dataNosema ceranae own data
literatureliterature
From Klee et al., 2007
2003 onwards
literatureNosema apis own data
Nosema ceranae own dataliterature
From
Pax
ton
et a
l., 2
007
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There seems to be a tendency for Nosema ceranae replacing Nosema apis
Is Nosema apis an endangered species weneed to protect !!??
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KOD LN Antal provAB Stockholm 54C Uppsala 36D Sdermanland 22E stergtland 63F Jnkping 62G Kronoberg 14H Kalmar 41I Gotland 0K Blekinge 10M Skne 82N Halland 64O Vstra Gtaland 346S Vrmland 54T rebro 49U Vstmanland 21W Dalarna 39X Gvleborg 10Y Vsternorrland 0Z Jmtland 0AC Vsterbotten 0BD Norrbotten 0
967 samples, 319 positive for MicrosporidiaOf these, 46 samples were mixed Nosema apis/Nosema ceranaeand 273 pure Nosema apis
2007
Table1.Numberofbeekeeperssampled(Beekeepers),numberofsamples(N)numberofsamplespositiveforNosemaspp.infection(+),proportionofsampleswithmixedinfectionsofN.apisandN.ceranae(Mixed)andproportionofN.ceranaeDNAinmixedinfections(Prop)forthreeyears(2007,2009and2011)inallsamplesanalysed. 2007 2009 2011Beekeepers 29 18 41N 46 110 81+ 30 29 18Mixed 0,77 0,63 0,56PropceranaeDNA 0,29 0,12 pending
Fors
gren
& F
ries,
201
1, u
npub
lishe
d
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What is driving this replacement process ?- differences in within host virulence ?- differences in infectivity ? - different rates of transmission efficacy ?
Available data from Sweden does not supporta continous replacement process
Nevertheless, N. ceranae has replaced N. apisin large parts of the world
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The mean relative amount of N. ceranae DNA 14 days post infection. Group 1 was infected with 10% N. ceranae and 90% N. apis, group 2 was infected with equal amounts of both species and group 3 was infected with 90% N. ceranae and 10% N. apis. The triangles indicate the proportion N. ceranae at the time of infection whereas the squares show the proportion 14 days post infection. Error bars show standard deviation.
From
For
sgre
n&
Frie
s, 2
010,
Vet
erin
ary
Para
sito
logy
170,
212
-217
.
170, 212-217
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The proportion infected bees 14 days post infection. Bees fed 10, 102, 103 and 104 spores of N. apis and N. ceranae respectively. Results presented as a mean based on three cages with 30 bees (n=90) for each treatment.
From Forsgren & Fries, 2010, Veterinary Parasitology, 170, 212-217 .
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4 6 8 10 12
The course of infection for N. apis and N. ceranae. Bees were individually infected with 10 000 spores of the respective parasite. At day 12 post infection, the infection is fully developed with a similar number of spores produced for both species.
From
For
sgre
n&
Frie
s, 2
010,
Vet
erin
ary
Para
sito
logy
, 170
, 212
-217
.
www.bee-doc.eu
What is driving this replacement process ?
- No competetive advantage within host- Slightly lower infective dose- Probably no difference in spore production
The dominance of N. ceranae in southern Europe, in the US and in South America remains an enigma
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Could disease impact be different in different climates?
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01
2
3
4
5
6
7
8
9
2 4 86 10 12
Days post infection
14
Log1
0 Sp
ore
coun
ts 20 C
25 C
30 C
35 C
Nosema apis
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2 4 86 10 12
Days post infection
14
Log1
0 Sp
ore
coun
ts 20 C
25 C
30 C
35 C
0
1
2
3
4
5
6
7
8
9
Nosema ceranae
www.bee-doc.eu
2 4 86 10 12
Days post infection
14
Log1
0 Sp
ore
coun
ts
20 C
0
1
2
3
4
5
6
Nosema apis
Nosema ceranae
www.bee-doc.eu
2 4 86 10 12
Days post infection
14
Log1
0 Sp
ore
coun
ts
25 C
0
1
2
3
4
5
6
7
8
9Nosema apis
Nosema ceranae
www.bee-doc.eu
2 4 86 10 12
Days post infection
14
Log1
0 Sp
ore
coun
ts
30 C
0
1
2
3
4
5
6
7
8
9Nosema apis
Nosema ceranae
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2 4 86 10 12
Days post infection
14
Log1
0 Sp
ore
coun
ts
35 C
0
1
2
3
4
5
6
7
8Nosema apis
Nosema ceranae
www.bee-doc.eu
2 4 86 10 12
Days post infection
14
Log1
0 Sp
ore
coun
ts
25 C
0
1
2
3
4
5
6
7
8
9Nosema apis
Nosema ceranae
Extracted from Raquel Martn-Hernndez et al., 2009
Spore dose: 10 000 100 000
Tissue examined: Ventriculus only Whole abdomen
There is a tendency for N. ceranae to growslower than N. apis at 20 and perhaps 25 C
There appears to be little difference in growth rate between parasite species at 30 and 35 C
Our data are not congruent with temperatureeffects reported by Martn-Hernndez et al., 2009
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0 0,2 0,4 0,6 0,8 1
Nosema apis
Nosema ceranae
N. apis, 1 week chilled
N. ceranae 1 week chilled
N. apis 1 week frozen
N. ceranae 1 week frozen Ten thousand spores
One thousand spores
Proprtion infected bees (N=25)
From Fries, I. 2010. Nosema ceranae in European honey bees (Apis mellifera). Journal of Invertebrate Pathology, 103, 573-579.
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There is a dramatic reduction on N. ceranaespore viability from freezing
This could possibly drive different rates oftransmission in different climates
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Thank you for your attention!And good luck with your bees!!