2nd TSB project meeting
Bio-control of grain storage
insect pests
Bryony Taylor, Dave Moore, Emma Thompson, Steve Edgington
Aims of work
• Create a formulation that:
• is compatible with existing spray
equipment
• produces a droplet range
appropriate for a contact
biopesticide
• has an even coverage.
• The undiluted formulation will:
• need to be stored without affecting
the viability of the conidia
• have minimal separation or
sedimentation
Aims of work
• If the formulation is to be used with a
knapsack sprayer:
• it will need to suspend readily in
a water based tank mix
• produce no clogging of the
nozzle.
•
If a ULV sprayer is considered the
formulation will need to be:
• oil based
• compatible with ULV sprayer
technology.
Considerations-Current application
technology used in grain stores
• 61% of farms use fabric treatments only to treat their
grain stores and a further 34% use both fabric and
grain treatments
• 56% of fabric treatments were applied using spray
technology which included knapsack and hand held
sprayers
• Other methodologies include fogging, dusting
(Pirimiphos methyl and silica), mist and smoke
Formulation issues
• Conidia are hydrophobic therefore
need co-formulants to disperse in
water
• Bb conidia lose viability quickly
when stored in a water based
formulation
• Emulsifiers need to be added to
break the surface tension
• Some have been shown to affect
conidial viability
• Careful screening needs to be
carried out
Co-formulants
• Co-formulants to be tested were
carefully considered and chosen
on the basis of:
• suitability
• previous research
• listing in the adjuvant
section of the UK pesticide
guide 2010
• availability (some have
been withdrawn)
Q: Are these co-formulants toxic to Bb?
Dispersents:
Sample
Bentone SD 1
Bentone SD 2
Contains
Action
Organically modified clay mineral (<2% Dispersant/Anti compaction
Quartz)
Organically modified clay mineral (<2% Dispersant/Anti compaction
Quartz)
Q: Are these co-formulants toxic to Bb?
Sample
Description
Purpose
Codacide
Addit
95% Rapeseed oil, plus 5%
emulsifiers
Emulsifiable vegetable oil
NuFarm
Cropoil
99% highly refined mineral
oil
Emulsifiable oil,
medium surfactant
Mixture of vegetable
oil, emulsifier and
wetting agent
Mineral oil, low
surfactant content
NuFarm
Output
60% mineral/40% w/w
surfactants
Mineral oil/ high
surfactant content
Newman
An emulsifiable concentrate
Cropspray formulation containing 99%
11E
highly refined paraffinic oil
Emulsifiable oil, low
surfactant content?
Label
recommended
amount
Min 2.5L/ha
(250ml in 100L
H2O)
3.125% max,
recommend
2L/200L/ha or
amenity land
Max 3.75L per
1000L of total
spray liquid
Max 2.5%
spray
Q: Are these co-formulants toxic to Bb?
Sample
Libsorb
Silwet L77
BreakThru
240
Purpose
Contains
Wetter
Alkyl alcohol ethoxylate
80% polyalkylene oxide modified Wetter
heptamethyltrisiloxane, max 20%
alloxypolyethylene gylcol methyl
esther.
Non-ionic spreading
Polyether-modified polysiloxane
S (Oxirane, methyl-, polymer with
and a penetration aid
oxirane, mono[3-[1,3,3,3tetramethyl-1[(trimethylsilyl)oxy]disiloxanyl]propyl]
ether
Amount in 100ml
Not available
Not above 5%.
Recommended
0.025-0.25%
Pesticides with
contact action: 125
ml/ha to
improve wetting and
spreading
200-300ml/ha arable
crops
Concentration
AIM: to deliver a dose of both 5 x 109
conidia per m2 and 2.5 x 1010 conidia
per m2
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For contact biopesticides it is recommended
that 50-70 drops per cm2
Normal amount of spray to apply to a
grainstore is 5l/100m2 which is also the
recommended amount on the Actellic 900
label
The FAO recommend this may be increased
on more porous surfaces to 10-20l/100m2 or
reduced when applied to metalwork.
We aimed to test formulations at these
concentrations
Concentration
• If the target application rate is 10L per 100m2 for
a porous surface, then we will need to apply:
1L for 10m2
100ml for 1m2.
• AIM: 5 x 109 and 2.5 x 1010 per m2
• Need to suspend these amounts of conidia in
co-formulant and then make up to 100ml using
H2O
Concentration
• Spores per gram were calculated
from a previously mass produced lot of
IMI 389521 (received July 2008).
• The average spores per gram were
calculated to be 6.7 x 1010
• Recent trials have shown that 75%
entostat:25% conidia has been
effective in trials using the dust
formulation, thus we will test at these
levels initially.
Experiment 1
Amount of
Weight of conidia for Entostat weight
co-formulant to mix 5 x 109 per m2
in the balance of
100ml water
1ml (1%)
0.075g
0.225g
• Codacide
• Addit
• Cropoil
• Output
• Cropspray 11E
• Silwet L77
Results
All adjuvants mixed
well after 1 minute
on the whirlimixer
Results
1 ml paste was mixed with 99ml
water to see if a stable emulsion
could be formed
Results
Codacide suspended easily forming
a consistent emulsion
Addit was slightly more difficult to
suspend and had ~10ml foam
Codacide
Addit
Results
Cropoil suspended well, but residue
left on glass
Cropoil
Output
Output adhered to the original tube
but with vigorous shaking
suspended. It dispersed well, but
had ~8ml of foam
Results
Cropspray 11E did not suspend in
water
Silwet L77 suspended easily.
Roughly 10ml foaming
Cropspray 11E
Silwet L77
After 16h
Codacide:
Yellow scum on top, large
particles settled at the bottom
of the tube
After 16h
Addit:
Foam reduced however
layer of white scum at top
and settling powder at the
bottom
After 16h
Cropoil:
Little sedimentation at bottom,
however layer at top observed
After 16h
Output:
Settling observed, little
floating matter
After 16h
Silwet L77:
Foam subsided, settling of
powder at the bottom
Experiment 2: Viability study
• 0.1 g conidia and 0.3g entostat
mixed with 8 co-formulants
• Conidia only and conidia+entostat
controls
• Kept at 5˚C and 25 ˚C
• Viability regularly checked
Viability Tests 5˚C
Viability Tests 25˚C
Conclusion
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Viability lower than previous batches (problem in
transport?)
Output co-formulant can be discounted
Variability may be due to large amount on
entostat/particles on plates
Continue and replicate studies
Observations
Settling
• During viability study, at both 5˚C and 25˚C ; all
liquid formulations re-suspended easily, even
after 28 days of storage
• All formulations showed settling of a fine
powder at the bottom of tube; apart from Silwet
L77
• However, there was a gelatinous ‘blob’ in the
middle of the 5˚C tube
Experiment 3
2.5 x 1010 formulations
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Codacide
Addit
Cropoil
Silwet L77
*Break-thru S 240* (new co-formulant)
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0.373g conidia + 1.193g of entostat (1:3)
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1ml of adjuvant added initially, then a further
1ml
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Water added to tube and inverted 10,20,30
times and 10sec, 20sec and 1min on the
whirlimixer
Those emulsifying were added to 98ml water
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Results
• 1 ml of liquid was not enough to
form a paste
• 2ml enough to form paste
• All paste were very viscous
• Codacide:
• Was not able to mix into water
• Waxy floating particles present
• Addit:
• Was difficult to form an emulsion
after inversions/using whirlimixer
• Eventual emulsion formed,
however large particles present
• In 98ml water, 10-20ml foam
• Cropoil
• Was not able to mix into water
• A waxy mat formed on top of the
water
• Silwet L77:
• Formed emulsion easily, although
some paste stuck to side of tube
• Dispersed well in water with 2030ml foam
• Break thru S 240:
• Mixed easily with water, with a little
sticking to sides of tube
• In 98ml water, after 10 inversions
30-40ml foam
Future
experiments
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Reduce settling with addition of varying
levels of clay
Repeat viability experiments and include
Breakthru
Look at particle sizing of promising
formulations
Investigate how well formulations spray
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AOB:
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Project student started this week
Molecular characterisation of isolate
underway
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Thank You