The recent advances in the integrated control of varroosis

Transcription

XI Jornadas Técnicas de Apicultura
Cordoba, 17 de Noviembre 2007
The recent advances in the
integrated control of varroosis
Antonio Nanetti
[email protected]
UR Apicoltura e Bachicoltura, Bologna, Italia
Population dynamics
10000 mites in mid-summer
COLONY DEATH
Starting point: 100 mites
The brood is over here
The brood starts again here
Mite reinvasion
Milani, 2001
Calendar: winter treatment
AUTUMN-WINTER
TREATMENT
Late winter
LESS THAN 50 MITES
Infestations double in one month
FEB
MAR
APR
MAY
JUN
JUL
AUG
10
20
40
80
160
320
640
50
100
200
400
800
1600
3200
100
200
400
800
1600
3200
6400
Calendar: summer treatment
AUTUMN-WINTER
TREATMENT
SUMMER TREATMENT
A critical period of the year!
Bees
Bees
Brood
Brood
Varroa
Varroamites
mites
40000
40000
1000
1000
900900
800800
700700
600600
N. of m ites
N. of m ites
N.
N.of
of adult
adult bees
bees // brood
brood cells
30000
30000
20000
500500
400400
300300
10000
200200
100100
0
31/3
0 0
30/4
30/4
30/5
30/5
29/6
29/6
29/7
29/7
28/8
28/8
27/9
27/9
27/10
27/10
26/11
26/11
26/12
26/12
Natural active ingredients
Compounds of essential oils
Thymol
Organic acids
Oxalic
Formic
Lactic (obsolete)
The thymol
Sublimates at room temperature
Melts at 50°C
Generally Recognized As Safe
Treatment with ground thymol crystals:
0,25 g per comb with bees on top bars
Uncontrolled release
Commercial formulations for a
controlled release
Api Life Var (Chemicals Laif)
Spongy tabs with
Thymol (8g)
Eucalyptus extract
Menthol
Camphor
Break and put the tab on the combs
Repeat 3 times at one-week interval
Apiguard (Vita Europe)
Gel (50g) with 12,5 g of thymol
crystals
One container on the combs
Top cover upside-down
Repeat twice at fortnight interval
Thymovar (Andermatt-Biocontrol)
Spongy tabs with 15-day of melted thymol
Put on the combs
Repeat twice at 14/21-day interval
Field comparison
Four Italian Institutes
Different environmental
conditions
Same protocol
Treatment: Aug/Sept
Climatic conditions
Apiary
VICENZA
MODENA
ROMA
PALERMO
Temp °C
RH%
20
(16-26)
19
(13-26)
25
(19-31)
27
(17-32)
75
(57-91)
70
(27-96)
-
Rain
mm
148
Bee
activity
Low
302
Low
22
High
41
High
Efficacy in hot conditions
100
80
60
40
20
0
RM
PA
Api Life Var
Apiguard
Thymovar
94,5
96,7
94,3
96,5
97,1
97,5
Efficacy in cold conditions
APIGUARD
Dehydrated surface
prevents further
release
100
80
60
THYMOVAR
Huge brood
removal
40
20
0
VI
MO
Api Life Var
Apiguard
Thymovar
95,1
92,4
66,9
68,3
93,6
Tolerability problems
Effect of environmental conditions
August 2005, North Italy, thymol treatments:
Low efficacy (30-50%)
Varroa uncontrolled
Huge damage (late summer-end winter)
Conjectures about poor efficacy
Product standardization
Varroa resistance to thymol
Normal weight and concentration
NO previous recordings
UNSUPPORTED by lab bioassays
Environmental factors
Unusual cold and rain period
Summer temperatures in 2005
Raffronto andamento
temperatura
dell'aria estate 2005
Monthly
avg. temperatures
28
MODENA
2003
27
26
°C
25
2004
- 6,2°C
24
23
- 2,5°C
22
2005
21
20
June
Giu
July
Lug
August
Ago
(treatment age)
Mesi
Anno 2005
Anno 2004
Anno 2003
Summer rainfall in 2005
Raffronto andamento
estate 2005
Monthlypiovosità
avg. rainfall
100
90
MODENA
80
2005
70
+ 79 mm
mm
60
50
+ 97 mm
2003
40
30
2004
20
10
0
June
Giu
July
Lug
August
Ago
(treatment age)
Mesi
Anno 2005
Anno 2004
Anno 2003
Summer daylight in 2005
Raffronto
andamento
ore di sole
estate
2005
Monthly
avg. sunlight
(hours
per
day)
12.00
MODENA
2003
11.00
10.00
- 2h 54m
ore
2004
9.00
- 1h 48m
2005
8.00
7.00
June
Giu
July
Lug
Mesi
Anno 2005
Anno 2004
August
Ago
(treatment age)
Anno 2003
Overall rainfall in summer 2005
VENETO REGION
The oxalic acid
Highly effective in broodless colonies
Tolerated by the bees
Easy to use and cheap
Natural: non-problematic for honey and
environment
OA is very popular in EU for varroa treatment
Metcalfa honeydew
350
300
250
Broken column:
761.4 mg/kg
Heather
Why is oxalic acid natural?
11
Very common in living beings and in foodstuffs
0
Natural content
of honey
(mg/kg)
Natural
oa content
acacia
3,3
agrum tarass giraso
eucali
castag metcal
asfod rodod lavan corbez rosma medic
tiglio
cardo
colza
timo
i
aco
le
pto
no
fa
elo endro da
zolo rino
a
19,5
29,6
31,5
36,5
49,0
55,6
91,1
270,8
15,8
22,5
22,6
25,0
25,2
38,4
45,7
54,5
Fir honeydew
Thymus
Alfalfa
Rosemary
Strawberry tree
Thistle
Eucalyptus
Lime tree
6
N<3
Lavender
6
4
Rhododendron
3
9
10
Rape
11
Sunflower
10
50
Dandelion
Citrus
100
False acacia
150
Asphodel
Chestnut
mg/kg
200
abete
erica
101,1 761,4
Administration: spraying…
Weak oxalic acid solution (2.1%)
Spray onto the bees (5 ml per comb)
Labour intensive (OBSOLETE!)
Germany
97.3% (Radetzki et al., 1994)
Italy
98.3% (Nanetti et al., 1995)
… trickling …
CONCENTRATIONS
sugar: 60%
oa:
4.2%
1:10
5 ml per comb
1:10:10
… sublimation
Heat up 2g OA and fumigate
Labour intensive
Needs a heat supplier
The oxalic acid as a chemical
Bi-carboxylic acid (IUPAC:
ethanedioic acid)
Bi-hydrate crystals
Solubility up to 10% (water)
Sublimates:
Dehydration (102°C)
Phase change (190°C)
Thermal cycle of oxalic acid
Oxalic acid
t=102°C
Water
(vapor)
(liquid)
(from air)
Co
o
lin
g
Water
Water
(bi-hydrate crystals)
Oxalic acid
Oxalic acid
(vapor)
t=190°C
Thermal degradation
H2O,UR
CO,
CO2, HCOOH
Apicoltura
e Bachicoltura, Bologna, Italia
Oxalic acid
(anhydrous crystals)
(amorphous solid)
1996: birth of a new method
Trickling an OA/sugar solution
Sugar concentration: 60%
Oxalic
acid concentration: 4.2% and 2.1%
100%
OA 4.2%
90%
(DB)
80% Dose: 5ml/comb with bees OA
2.1%
75%
Mite mortality
70%
60%
50%
50%
40%
30%
25%
20%
10%
0%
0
2
4
6
8
10
UR Apicoltura e Bachicoltura, Bologna,Days
Italiaafter treatment
12
14
16
Efficacy of OA trickling
100
90
80
Efficacy%
70
60
4.2% OA
96.8%
50
40
30
20
10
0
2.1% OA
89.5%
A minimum thermal threshold?
Seven (1/18)
groups
8,4
3,2
(-3/5)
100%
Average (min-max) weekly temperature
3,7
(-4/10)
-
-1,5
(-9/9)
-0,7
(-5/10)
-0,4
(-7/10)
18/12
24/12
90%
Trickling
(OA 4.2%, sugar 60%)
80%
Avg efficacy: 98.1%
Average efficacy
70%
broodless
wintered colonies
60%
50%
Single
administrations, different ages
40%
30%
Temperature
recordings
20%
10%
0%
06/11
13/11
20/11
27/11
Date of treatment
11/12
Comparative trial
Climatic areas:
Two 50-colony apiaries:
Continental (MODENA)
Mediterranean (SIENA)
Trickling:
3 groups
Sublimation: 1 group
Untreated:
1 group
Treated groups
TRICKLING
Group
OA% sugar%
Original
4.2
60
Low OA
3.2
60
Low sugar
4.2
30
SUBLIMATION
Standard dose
2g b-OA
(1.4g OA)
Daily mite fall
160
Number of varroa mites
140
Sublimation
Original
Low OA
Low sugar
Untreated
120
100
80
60
40
20
0
17.12
24.12
31.12
7.1
14.1
21.1
28.1
Efficacy
100%
80%
87,7%
60%
87,1%
90,9%
70,3%
40%
20%
Low sugar => low efficacy
0%
Original
Low sugar
Low OA
Sublimation
Expected acaricidal activity >90%
Mode of action
What do they say?
E
T
R
A
!
T
C
A
F
“Varroa proboscis!”
“What? This is a LEG!!”
“The OA burns skin and hairs!”
Mode of action: hypothesis 1
CALCIUM
Tenaza [Español] = Chela [Latin]
Metabolic Ca chelation (toxic effect in mammals)
Ca is bound => Ca (COO)2
unavailable to the metabolism
oxalate stones in the kidneys
OXALIC ACID
Non-chelation dependent mortality
100
90
% mite mortality
80
70
60
50
40
30
20
10
0
Oxalic acid
Chelating agent
Mode of action: hypothesis 2
+
-
Solution acidity
Two carboxyls
Short chain
Highly dissociated
+
pH/concentration relationship
Propionic
Acetic
Citric
Formic
Tartaric
Lactic
Oxalic
4
pH
3
2
1
0
0
5
10
Concentration (%)
15
Acidity dependent mortality
100
90
% mite mortality
80
70
Oxalic acid
pH 1
60
50
40
30
20
10
0
Spraying
Trickling
Same oxalate concentration in each comparison
Potassium oxalate
pH 7
Saturated OA solution
RH > 86%
Water from the air Evaporation
RH < 86%
Evaporation
BUT
if we add sucrose the
equilibrium
lowers to 69%
Water from the air
Oxalic acid
crystals
Effect of humidity on mortality
A synergic action of sucrose
Varroa mortality (%)
42% RH
22.3
25.2
OA alone
OA + sucrose
75% RH
30.0
53.7a
From Milani, 2001
a
In this case the OA absorbs water from the air (RH>69%)
Treatment in coated capsules
Relative humidity in the colony
100
EXTERNAL
90
80
70
RH%
60
50
40
30
CLUSTER
20
10
0
17.12
24.12
31.12
7.01
14.01
21.01
Relative humidity in the colony
100
EXTERNAL
90
80
70
RH%
60
50
40
30
CLUSTER
20
10
0
17.12
24.12
31.12
7.01
14.01
21.01
Weak sugar sols may crystallise
Previous trial. Higher RH% …
100
90
80
70
60
%
50
40
30
External
20
Centre of cluster
10
0
23/12
30/12
6/1
13/1
… and better efficacy also
100%
94,3%
93,8%
92,9%
Trickling (60%)
Trickling (30%)
Trickling (15%)
80%
60%
40%
20%
0%
[OA]=4,2%
Action by contact
False colours
Yellow: light impression on film
Pink: heavy impression on film
Adult bee population
PRE-TREATMENT
CONTINENTAL
MEDITERRANEAN
8840
10530
N. of bees
POST-TREATMENT
ORIGINAL
LOW SUGAR
LOW OA
SUBLIMATION
UNTREATED
Decrease during winter
-26.7%
-32.1%
-25.6%
-34.7%
-20.0%
-12.5%
-18.9%
-15.4%
-7.8%
-26.6%
Brood amount
PRE-TREATMENT
N. of cells
CONTINENTAL
MEDITERRANEAN
broodless
broodless
1511
1275
1487
1360
1615
11097
10370
10157
9520
10880
POST-TREATMENT
ORIGINAL
LOW SUGAR
LOW OA
SUBLIMATION
UNTREATED
Sublimation: OA microcrystals
Micro-particle inhalation
PENETRATION
SIZE
(micrometer)
Nose
7.0
-
11.0
Pharynx
4.7
-
7.0
Trachea – Bronchi
3.3
-
4.7
Bronchi
2.1
-
3.3
Bronchioles
1.1
-
2.1
Primary alveoli
0.65
-
1.1
Secondary alveoli
0.43
-
0.65
From G.C.Ceschel
“Multivarrox”
Sublimation: unexpected risk
Contamination is possible while:
- TREATING
- COUNTING THE FALLEN MITES
- CHECKING THE OUTWINTERED COLONIES
Thanks for your attention
Acaricides allowed in EU25
(Reg. 2377/90)
Allegato I (limiti *)
Amitraz
Cimiazolo
Cumafos
200
1000
100
*(microg/kg miele)
Allegato II (NO
limiti)
Consentiti in apicoltura
biologica
(UE Reg. 1804/99)
Fluvalinate
Flumetrina
Timolo
Eucaliptolo
Canfora
Acido lattico
Acido formico
Acido ossalico

The recent advances in the integrated control of varroosis

Transcription

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