CATTS Quarantine Treatments
for Tree Fruits
Lisa G. Neven
USDA-ARS
Yakima Agricultural Research
Laboratory
CATTS
Controlled
Atmosphere
Temperature
Treatment
System
Controls & Monitors:
O2, CO2, Air Speed,
Humidity, Dew Point, Air
Temperatures, Heat Rate,
Fruit Temperatures
(surface & core)
What CATTS Does




Oxygen is reduced to a level which will
not support active metabolism in the
insects.
High carbon dioxide levels prevents the
insect from ‘down regulating’
metabolism and respiration.
High temperatures cause metabolic
stress in the insect, and large scale
systems break down occurs.
Combination CA & Heat causes
mortality about 2X as fast as heat alone.
Zone of
Opportunity
Host
Tolerances
Pest
Intolerances
Illustration of the ‘zone of opportunity’ for optimization of
insect mortality and commodity quality using a heat treatment.
Host
Tolerances
Zone of
Opportunity
Pest
Intolerances
Illustration of the ‘zone of opportunity’ for optimization of
insect mortality and commodity quality using a CATTS treatment.
Considerations for CATTS
Treatments
Fruit Physiology
 Insect Physiology
 CATTS Treatments
 Engineering of Commercial Units

Fruit on the Tree



While fruit are on the tree, they
experience fluctuating temperatures.
In response to these fluctuating
temperatures, the fruit produce a
number of ‘stress response’ proteins.
The fruit will produce these proteins
even if the daily temperatures are not
in the ‘stress’ range every day.
Apple Temperatures During a
Typical Summers’ Day in Washington State
Temperature °C
August 12
41.3°C
41.5°C
42.0
37.0
32.0
27.0
22.0
17.0
12.0
Time
air
deep
shallow
deep
Peach Fruit Temperatures
on the tree
120
Temperature °F
110
C1
100
C2
90
80
C3
70
C4
60
Time
Cherries on the Tree in
Tasmania
45
40
35
Degrees C
1
30
2
25
3
4
20
5
15
6
7
10
8
5
0
22-Dec
23-Dec
24-Dec
25-Dec
26-Dec
27-Dec
28-Dec
29-Dec
30-Dec
31-Dec
Cherry core temperatures in Tasmania,
Australia where daily high air temperatures are
below 30°C.
1-Jan
Fruit after Harvest


After harvest, the fruit will continue to
make the ‘stress response’ proteins for
a number of days.
These proteins will help the fruit
tolerate heat treatments.
Fruit and CATTS




There is no evidence that the high
carbon dioxide and low oxygen levels
during CATTS causes any additional
phytotoxicity.
This may be due to the high capacity
for anaerobic metabolism in the fruit.
We do know that heating rate is very
important for preventing damage.
We also know that heat disrupts many
of the enzymes involved in ripening.
Insects in the Fruit



Insects in the fruit will also produce ‘stress
response’ proteins when fruit temperatures
reach ‘stressful’ levels.
Insects will only produce these proteins
when they experience stressful
temperatures.
When the fruit is harvested, and the insects
are no longer exposed to stressful
temperatures, they do not produce stress
proteins.
Stress Proteins and CA
Insects cannot produce ‘stress
response’ proteins if there is not
enough oxygen to support
metabolism.
 We are not EXACTLY sure about
the fruit, but we do fruit have a
high capacity for anaerobic
metabolism.

Scanning Metabolic Heat Rate
Heat Rate µW/mg FW
Heat Rate uW/mg
15
15
11
11
9
7
7
3
3
-1-1
-5-5
25
30
Air
1% O2
35
Temperature °C
15% CO2
40
45
1% O2/15% CO2
Isothermal Heat Rates
Heat Rate µW/mg FW
8
7
6
5
4
3
2
1
0
0
5
10
15
20
25
30
35
Temperature °C
40
45
50
Codling Moth Pupal Respiration
0.06
ul CO2/mg/min
0.05
Whole Range
uL CO2/mg/min = 0.001533 X Temp -0.00809
R2 = 0.977207
0.04
0.03
0.02
10-30°C Range
uL CO2/mg/min = 0.001942 X Temp -0.01618
R2 = 0.998422
0.01
0
5
10
15
20
25
30
Temperature °C
35
40
2
1
0
0
50
MOIST 48°C
4
50
45
3
40
2
35
30
1
25
0
0
50
100
150
200
TIME (min)
250
20
300
TEMPERATURE °C
3
50
45
40
35
30
25
20
100 150 200 250 300
TIME (min)
TEMPERATURE °C
4
ul CO2/mg/min
ul CO2/mg/min
VAPOR 48°C
Importance of Heating Rate


We know that the faster the rate of
heating, the shorter the time the
insects have to be held at the final
treatment temperature to kill them.
For example, CATTS at 12°C/h to
final temperature of 46°C the core
average temps have to be at 45°C
for 30 min, while CATTS at 24°C/h to
the same temperatures, cores only
have to be at 45°C for 15 min.
Time at Final Temperature
versus Heating Rate
Time at Final Temp. (Hr)
ln(LT95) = b0 + b1ln(heat rate) + b2 (treatment temperature)
40
Where...
b0 = 22.4462 + 1.0486 SE
30
b1 = -1.5745 + 0.09844 SE
b2 = -0.2970 + 0.02339 SE
20
R2 = 0.972
10
0
0.06
0.08
0.1
0.12
0.14
0.16
Heat Rate
42
44
46
0.18
0.2
DSC
ATP Levels
180
= Air
160
= 1% O2
ATP nM/mg
140
= 15% CO2
120
= 1% O2/15% CO2
100
80
60
40
20
0
A
B*
C*
D*
E*
Treatment Type
F
G
H
Diapause CM Oxycaloric Ratio
Treatments against…..

Codling moth

Oriental fruit moth

Western Cherry fruit fly
Treatments developed for..
 Sweet
Cherries
 Apples
 Peaches
 Nectarines
Sweet Cherry CATTS

Two treatments have been developed
and efficacy tests (5,000 killed, 0
survivors) against both CM and WCFF
have been performed.
25 min at 47°C with 1% O2, 15% CO2.
 45 min at 45°C with 1% O2, 15% CO2.



Fruit quality better than Methyl Bromide
fumigated.
No commercial application has meet
with specifications.
Efficacy & Confirmation
Tests
Western Cherry Fruit Fly
 45°C—6315 treated
with 100% Mortality.
 47°C—5800 treated
with 100% Mortality


Codling Moth
45°C—5076 treated
with 100% mortality.
47°C: 5759 treated
with 100% Mortality.
Apples





Two treatments developed.
12°C/h, 3h, chamber at 46°C with 1%
O2, 15% CO2
12°C/h, 4h, chamber at 44°C with 1%
O2, 15% CO2
Efficacy tests on CM and OFM using
#1.
Confirmatory tests on CM completed
using #1.
CATTS Conditions for an Apple
Quarantine Treatment
50
25
45
20
40
15
35
10
30
25
5
20
0
0
50
100
150
200
Time (min)
Supply
Core
Sur
O2
CO2
% Atmosphere
Temperature °C
12°C/hr
Fruit quality
 CATTS
before storage helps
maintain quality by…
 Maintaining
firmness
 Preventing storage scald
 Delaying ripening
 Delaying decay
 Increases SS/TA ratio (sweeter)
CATTS treatment of apples using 12°C/h,
46°C final chamber temperature, 1% O2, 15%
CO2, -2°C dew point, and 2 m/s air speed.


Efficacy Tests
CM: 5728
treated. 100%
Mortality.
OFM: 5497
treated. 100%
mortality
Confirmation Tests
 CM: 31, 271
treated. 100%
mortality
Stone Fruits
Treatments developed:
 12°C/h, 3h, chamber at 46°C with
1% O2, 15% CO2
 24°C/h, 2.5h, chamber at 46°C
with 1% O2, 15% CO2
 Efficacy tests on both CM and
OFM.
 Confirmatory tests on CM.
Stone Fruit CATTS
Efficacy Tests

Oriental Fruit Moth
24°C/hr—5453
treated. 100%
mortality.
 12°C/hr—5674
treated. 100%
mortality

Confirmation Test

Codling Moth
24°C/hr—31,154
treated. 100%
mortality.
 12°C/hr—30,884
treated. 100%
mortality

Fruit quality
 Helps
maintain quality by…
 Delaying
ripening
 Increasing extractable juices
 Increasing shelf life
 Barely perceptible changes in
quality as compared to
untreated controls.
Status of Commercialization




There is a 2 ton CATTS unit in WA.
The two pallet unit in Parlier, CA.
Thermo Tech Inc. in CA is making a
‘CATTS ready’ unit that is a forced air
cooling system.
ECO2 in the Netherlands is making
commercial units for sale, lease, and
treatment contract.
Lab-Scale CATTS





Air flow from bottom
of unit to top.
Maintains 1-2 m/s
air flow.
CA established
within 15 min.
No water on fruit
surface.
Heating rates up to
100°C/hr.
Bin Configured
Commercial
CATTS
Chamber
Placing temperature probes
in apples.
Technicians after placing a mixed
load into the 2 ton CATTS unit.
Bin Unit






Horizontal air flow.
Flow of ~1 m/s
CA established in 20-30 min using
nitrogen flush.
Humidification with micromisters.
Different bin/container configurations
possible.
Heating rates up to 50°C/hr.
Pallet Configured CATTS Unit in
Parlier, CA
Pallet Configured CATTS





Horizontal air flow less than 1 m/s.
Humidification with micromisters.
CA established in 30 to 60 min.
Heating rates up to 100°C/hr.
Does not work well with packed boxes.
Critical Factors for
Commercial Units






Air flow maintained throughout load.
No water on fruit surfaces.
Oxygen levels 1.0% or lower.
Carbon dioxide levels between 10 to
15%.
Treat freshly harvested fruit within 5
days of harvest.
Do not treat fruit with pulp
temperatures below 15°C.
Thank You!