How to overcome the egg-weakness
of sulfuryl floride –
combinations of control methods
Christoph Reichmuth and Dagmar Klementz
Federal Research Institute for Cultivated Plants, Julius Kühn-Institute (JKI)
Institute for Ecological Chemistry, Plantanalysis and Stored Product Protection
Berlin, Germany
MBAO, Postharvest Session V, November 12, 2008, Orlando Fl.
Reichmuth and Klementz
Vision

Consequence of
laboratory and field data:
Necessity to modify the actual
fumigation schedules for SF to ensure
complete control (incl. egg stages) of
some pest insects like especially
the Flour Beetles Tribolium spec.
MBAO, Postharvest Session V, November 12, 2008, Orlando Fl.
Reichmuth and Klementz
Aim
Identify approach(es):
include all egg stages
of tolerant species into
the control program with SF.
 Use available information!

MBAO, Postharvest Session V, November 12, 2008, Orlando Fl.
Reichmuth and Klementz
Today‘s situation



Germany (also elesewhere?) 2006-2008:
nearly 50% of checked SF mill treatments
left considerable numbers of
surviving pest insects behind
(eggs survived within weeks)
(ref. ASSOCIATION of GERMAN MILLERS
Also in the UK (e.g. Dr. Kenneth MILLS)
found surviving pest insects despite
strict dosage schedules.
MBAO, Postharvest Session V, November 12, 2008, Orlando Fl.
Reichmuth and Klementz
Why this problem?
Adoption of theoretical laboratory
mortality data for practical field use:
much higher safety margins required:
- variation of temperature/leakage
- estimation of the real concentration
where the insects hide
 - gas and heat convection
within the object}

MBAO, Postharvest Session V, November 12, 2008, Orlando Fl.
Reichmuth and Klementz
Possible approaches:
- increased dosage of sulfuryl fluoride or
- combination of sulfuryl fluoride with






1: heat
2: phosphine
3: carbon dioxide
4: hydrogen cyanide
5: pulsed fumigation
6 other (e.g. like PPO+CO2)
MBAO, Postharvest Session V, November 12, 2008, Orlando Fl.
Reichmuth and Klementz
Basic considerations
species
stages
eggs
Tribolium
castaneum post
embryonic
full lethal
ct product in
reference
gh/m³ at 25°C
1,669
113
BELL et al.,
2003
Question: Which ct product is appropriate
(LD 99.9%, eggs, larvae, pupae and adults)
for practical field conditions??
{BELL (1988):
5g/m³ MB sufficient in the laboratory; field: 20g/m³ for
structural
}
MBAO, Postharvest Session V, November 12, 2008, Orlando Fl.
Reichmuth and Klementz
Basic considerations
species
stages
eggs
Tribolium
castaneum post
embryonic
Full lethal
ct product in
gh/m³ at 25°C
1,669
113
reference
BELL et al.,
2003
Question: Which ct product is appropriate?
Correction factor of about 3 reasonable:
4,500gh/m³ instead of 1,669gh/m³ for all stages
or 300gh/m³ instead of 113gh/m³ for post embryonic stages.
MBAO, Postharvest Session V, November 12, 2008, Orlando Fl.
Reichmuth and Klementz
Solution 1




SF and heat (>35 C)
Advantage:
within the label
Disadvantage: heat damage, distribution
Costs: increased by about factor 2*
compared to SF alone
_________________________________
* this and the follwing fiures are raw estimates!
MBAO, Postharvest Session V, November 12, 2008, Orlando Fl.
Reichmuth and Klementz
Solution 2




SF and phosphine
Advantage:
within label
Disadvantage: corrosion,
expanded down time
Cost:
Factor 1.5* compared to SF alone
MBAO, Postharvest Session V, November 12, 2008, Orlando Fl.
Reichmuth and Klementz
Solution 3




SF and carbon dioxide
Advantage:
Combination with inert atmospheres,
possibility to combine with heat
Disadvantage: Expected long exposure
Cost: Fairly higher than SF alone
MBAO, Postharvest Session V, November 12, 2008, Orlando Fl.
Reichmuth and Klementz
Solution 4




SF and hydrogen cyanide
Advantage:
little gas of each
Disadvantage: label, two compounds,
worker safety
Cost: not necessarily more since only
small amounts of both fumigants
necessary
MBAO, Postharvest Session V, November 12, 2008, Orlando Fl.
Reichmuth and Klementz
Av. number of survivors of all life stages of
Tribolium castaneum (Tc) and Sitophilus granarius (Sg):
48 h sulfuryl fluoride (SF) alone, hydrogen cyanide (HCN)
alone, or a combination of SF and HCN, 23°C, 65% r.h.#
SF: 20g/m³
SF: 20g/m³ +
no SF
1.5g/m³ HCN
no HCN
1.5g/m³ HCN
average number of survivors,
counted as adults (Tc/Sg) after 12 weeks
4/4
0/0
6/9
Untreated: 40/71
#Patent of K.MBAO,
BÄUMERT
andSession
H.-J. BELT,
2002,12,
DE2008,
10110570A1
Postharvest
V, November
Orlando Fl.
Reichmuth and Klementz
Solution 5




+
SF and repeated treatment in
intervals (Pulsed Fumigation)+
Advantage: no other chemical, within the label
Disadvantage: longer down time,
MRL problem(?)
Cost: nearly factor 2, depending on the sealing
necessities, may be less since the single
fumigation requires less SF to control
susceptible stages
_________________________________
European Patent by Binker company
MBAO, Postharvest Session V, November 12, 2008, Orlando Fl.
Reichmuth and Klementz
Pulsed Fumigation, basic considerations
species
stages
eggs
Tribolium
castaneum post
embryonic
Full lethal
ct product in
gh/m³ at 25°C
reference
1,669
113
BELL et al.,
2003
Question: Which ct product
and time interval (length of pulse, how many days?
between the two fumigations is appropriate
(LD99.9%, larvae, pupae and adults)
for practical
field conditions (safety factor?)?? Reichmuth and Klementz
MBAO, Postharvest Session V, November 12, 2008, Orlando Fl.
Pulsed Fumigation, basic considerations
species
stages
eggs
Tribolium
castaneum post
embryonic
Full lethal
ct product in
gh/m³ at 25°C
reference
1,669
113
BELL et al.,
2003
Question: Which ct product (30g for 10h or 10g for 30h)
and time interval (length of pulse, how many days?
ct=300gh/m³?) between the two fumigations is appropriate
(LD99.9%, larvae, pupae and adults)
for practical
field conditions (safety factor aboutReichmuth
3)?? and Klementz
MBAO, Postharvest Session V, November 12, 2008, Orlando Fl.
Pulsed fumigation, dosage
SF concentration ing/m³
100
300gh/m³
Safety margin ca. 3 for
leakage,
uneven gas distribution,
temperature differences
113gh/m³
field
field
ct = 300gh/m³
10
laboratory
laboratory
ct = 113gh/m³
1
0
10
24
30
48
72
Fumigation time in hours
Model T. cast.
25°C
MBAO,
PostharvestPossible
Session V, November
12, (t
2008,
Orlando
Fl. obtain a ct product
Reichmuth and
dosages
and
c) to
of Klementz
300gh/m³
Pulsed fumigation, dosage
SF concentration ing/m³
100
300gh/m³
Safety margin ca. 3 for
leakage,
uneven gas distribution,
temperature differences
30
113gh/m³
field
field
ct = 300gh/m³
10
laboratory
laboratory
ct = 113gh/m³
1
0
10
24
30
48
72
Fumigation time in hours
Model T. cast.
25°C
MBAO,
PostharvestPossible
Session V, November
12, (t
2008,
Orlando
Fl. obtain a ct product
Reichmuth and
dosages
and
c) to
of Klementz
300gh/m³
Pulsed fumigation, dosage
SF concentration ing/m³
100
300gh/m³
Safety margin ca. 3 for
leakage,
uneven gas distribution,
temperature differences
30
113gh/m³
field
field
ct = 300gh/m³
10
laboratory
laboratory
ct = 113gh/m³
1
0
10
24
30
48
72
Fumigation time in hours
Model T. cast.
25°C
MBAO,
PostharvestPossible
Session V, November
12, (t
2008,
Orlando
Fl. obtain a ct product
Reichmuth and
dosages
and
c) to
of Klementz
300gh/m³
Pulsed fumigation, pulse length
Development of stages, model for Tribolium castaneum
eggs
30°C
larvae
pupae
t30
adults
20°C
t20
0
10
20
30
40
50
60
70
developmental
timeOrlando
in days
MBAO, Postharvest Session
V, November 12, 2008,
Fl.
80
90
100
Reichmuth and Klementz
Pulsed fumigation,
length of time (pulse) between two consecutive
fumigations with 300gh/m³: 14 days
1800
1600
hatch of larvae with lower tolerance
eggs
larvae
pupae
adults
1400
ct in gh/m³
1200
1000
800
ct to control post embryonic stages with safety margin
600
400
300
ct to control post embryonic stages
200
0
0
10
20
30
MBAO, Postharvest Session V, November 12, 2008, Orlando Fl.
Time in days
first fumigation
second fumigation
40
50
Reichmuth and Klementz
60
Pulsed fumigation,
length of time (pulse) between two consecutive
fumigations with 300gh/m³: 14 days
1800
1600
hatch of larvae with lower tolerance
eggs
larvae
pupae
adults
1400
ct in gh/m³
1200
1000
800
ct to control post embryonic stages with safety margin
600
400
300
ct to control post embryonic stages
200
0
0
10
20
30
MBAO, Postharvest Session V, November 12, 2008, Orlando Fl.
Time in days
first fumigation
second fumigation
40
50
Reichmuth and Klementz
60
Conclusions
to overcome the egg-weakness of SF by
- increased SF dosage (limitation label and cost) or
Combination with






1: heat
2: phosphine
3: carbon dioxide
4: hydrogen cyanide
5: pulsed fumigation
6: others?
*but promising
clumsy*
limited
expensive
cheap but clumsy*
time consuming*
MBAO, Postharvest Session V, November 12, 2008, Orlando Fl.
Reichmuth and Klementz
Any problem with SF?
Its the insect egg, stupid!
(free after former US President Bill Clinton)
MBAO, Postharvest Session V, November 12, 2008, Orlando Fl.
Reichmuth and Klementz