Effects of heat and modified atmospheres on insects. Lisa G. Neven ARS Yakima Agricultural Research Laboratory Wapato, WA

Transcription

1 Effects of heat and modified atmospheres on insects Lisa G. Neven USDA-ARS ARS Yakima Agricultural Research Laboratory Wapato, WA

2 Heat Treatments For Fresh Commodities Types of Treatments Hot Water (Dips, drenches, or sprays) Vapor Heat Hot Forced Air (non-condensing) Microwaves Radio Frequency Types of Responses Metabolism Respiration Nervous System Endocrine Heat Shock Proteins

3 Hot Water Dips

4 Hot Forced Air

5 Factory Hot Forced Air

6 Temperature at and 2mm below fruit surface Heating Media at 48 C Surface: Vapor-pressure-deficit, forced-air Below surface Surface: Vapor-saturated, forced-air Below surface Surface: Hot water Below surface Time (min) K. Shellie, USDA-ARS

7 Electromagnetic Energy Is it heat? Is it radiation? Is it something else? (dielectric effect) 915 MHz 2450 MHz Microwaves MHz Radio waves Infrared Utra violet

8 Comparison of Thermal and Radio Frequency Treatments Heat Diffusion Radio Frequency Conduction Object Heat Source Object Source James Hansen, USDA-ARS, ARS, USA

9 Radio Frequency Treatments See a higher level of mortality over that which can be explained by thermal mortality. It appears to be part thermal and part dielectric effects on mortality.

10 James Hansen, USDA-ARS, USA

11 (S. Wang and J. Tang, WSU) Temperature profiles of walnut kernels and codling moth slurry when subjected to 27 MHz RF system

12 Microwave Treatments Appears to be very effective in treatment of insects in dry commodities. Insects heat faster due to water content. Some limited success in fresh produce. Mortality still an effect of heating.

13 Terminology of Temperature Change Step Function: : refers to a change from one temperature to another as rapidly as possible Step-function transfers reveal how rapidly an insect can respond to a thermal challenge. Example: : water bath studies in which insects are immersed directly into heated water (or other aqueous medium) (Sharp and Chew 1987, Jang 1991) (Clarke 1967)

14 Terminology of Temperature Change Ramp Function: : is when a slower rate of change in temperature occurs Ramp-function heat treatments can reveal, through examination of the response curve, what mechanisms may be involved in thermal tolerance and indicate whether the tolerance limits of the insect is wider in response to a ramp than to a step function. Example: : In-fruit heat treatments or controlled water bath treatments (Shellie 1997, Neven 1998a,b) (Clarke 1967)

15 Important Factors Affecting Heat Treatments Temperature of treatment Insect thermal limits Rate of heating Acclimation vs. acclimatization Duration of heat treatment Range from sub-lethal to lethal responses Insect Milieu Location in commodity Physical state of commodity surrounding insect

16 Q10 Effects Q10 Velocity (T + 10 ) = Velocity (T ) Q10 = OR )10/ (T ( k 2 ) 2 T 1 ) k 1

17 Arrhenius plots of PK activity from muscle and fat body of Acheta domesticus after periods at various acclimation temperatures. (After Hoffman and Marstatt 1977) AT 10 C AT 20 C AT 30 C / T K ET C

18 Temperature Effects on Metabolism Heat Rate uw/mg Temperature C

19 Time at Final Temperature versus Heating Rate ln(lt 95 ) = b 0 + b 1 ln(heat rate) + b 2 (treatment temperature) Time at Final Temp. (Hr) 40 Where... Where b0 b0 = SE SE b1 b1 = SE SE 20 b2 b2 = SE SE R 2 2 = Heat Rate

20 Respiratory Response to Heat Treatment Fifth instar codling moth CO 2 production during a simulated heat treatment of apple Note characteristic peak followed by rapid decline in CO 2 production. ul CO2/mg/min ul CO2/mg/min TIME (min) VAPOR 48 C MOIST 48 C TIME (min) TEMPERATURE C TEMPERATURE C

21 ul CO2/mg/min Codling Moth Pupal Respiration Whole Range ul O2/mg/min = X Temp R2 = C C Range ul O2/mg/min = X Temp R2 = Temperature C

22 Respiration of fifth instar codling moth at constant temperature ulco2/mg/min TEMPERATURE C Linear Fit RESP

23 Omnivorous Leafroller Pupal Respiration 0.09 ul CO2/mg/min Temperature C

24 Effect of temperature cycling on the metabolic heat rate at 20 C of green peach aphids (M. persicae), expressed as a percentage of the original value, as a function of the stress temperature and number of cycles to the stress temperature. From: Downes et al

25 Apple Temperatures During a Typical Summers Day August C 41.5 C 3:05 4:35 6:05 7:35 9:09 10:39 12:09 1:39 3:09 4:39 6:09 7:39 9:09 10:39 12:09 Time air deep shallow deep 12:05 1:35 Temperature C

26 Peach Fruit Temperatures Peach Fruit Temperatures on the tree 12:00:00 12:00:00 AM AM 12:00:00 12:00:00 AM AM 12:00:00 12:00:00 AM AM Time C1 C2 C3 C4 12:00:00 12:00:00 AM AM 12:00:00 12:00:00 AM AM Temperature F Temperature F

27 MODELS OF THERMAL DAMAGE Roti Roti (1982) suggests that the effects of heat on macromolecules is the critical element of thermal damage. Bowler (1987) points to damage of the cell membrane as the critical event.

28 THERMAL DAMAGE: It s a matter of Degrees Macromolecules Cells Tissues Whole Organism (most sensitive) Increasing Resistance to Heat Damage

29 HEAT SHOCK PROTEINS Heat shock proteins are classified as to the molecular weight on SDS-PAGE. General classes: low molecular weight kda HSP70 s Most common in insects HSP90 s HSP >100 kda

30 HEAT SHOCK PROTEINS Denatured Spontaneous Renatured Facilitated + DnaK DnaJ GrpE Folding Complex + GroEL GroES <Association/Dissociation>

31 Heat Rate and HSP s Thomas & Shellie 2000 described a reduction in the percent of Mexfly larvae expressing a HSP28 in relation to the rate of heating. The more rapid the rate of heating, the lower the percentage of the larvae expressing this HSP.

32 Heat Shock Proteins and Anoxia The production of heat shock proteins in insects is inhibited under anoxic conditions. (Yocum( & Denlinger 1994).

33 Types of CA Treatments Time Temperature Atmosphere Low Temperature CA: 0-15 C, 0-5% 0 O 2, 0-10% 0 CO 2. Long duration. High Temperature CA: C, 0-5% 0 O 2, 0-60% 0 CO 2. Short duration. MAP (Modified Atmosphere Packaging): 0-20 C, 1-18% 1 18% O 2, 0-10% 0 CO 2. Long Duration Film Wraps: C, 27 C, variable ATM, long duration. Coatings: 0-50 C, variable ATM, short or long duration.?!? Hot Water Dips: C, 1-10% 1 10% O 2, 0-10% CO 2. Short Duration.

34 Temperature Time Atmosphere Coating or Film?

35 Concentration inside fruit (kpa) Isothermal Heat Doses Carbon Dioxide Time (h) Hot air Hot 1 kpa O kpa CO 2 Hot water Oxygen K. Shellie, USDA-ARS

36 CA Mode of Action on Insects Time Temperature Atmosphere >10% CO 2 stops production of NADPH which aids in detoxification Energy charge is reduced, slowing processes requiring ATP. Production of glutathione (used in MeBr detoxification) is reduced. High CO 2 inhibit regeneration of choline to acetylcholine. Friedlander 1983.

37 Temperature Time CA and Metabolic Heat Rate Atmosphere Decrease in heat rate with decreasing O 2. Critical O 2 levels (P c ) increased with temp. Metabolic heat rate decreased rapidly at 20% CO 2, but little change up to 79%. Additive effects realized at <5% CO 2 and >4% O 2. High susceptibility to CO 2 at high temps. related to high metabolic heat rates. Low O 2 response correlated to metabolic arrest and anaerobic metabolism. Zhou et al. 2000

38 Temperature Time CA and Metabolic Response Atmosphere Decrease in MHR with increasing CO 2 and decreasing O 2. Recovery by pupae when MHR reduced by 30%. MHR decrease by 50% resulted in death. Mortality equivalent between 5% CO 2 and 6% O 2, and 10% CO 2 and 2% O 2. Effects of low O 2 and elevated CO 2 on membrane permeability. Zhou et al. 2001

39 % Decrease in Metabolic Heat Rate Platyona stultana pupae Time Temperature Atmosphere 100 % Decrease in MHR %CO2 %O2 Zhou et al. 2001

40 % Decrease of Metabolic Rate of Codling Moth Pupae Under Varying Temperatures and Concentrations of Carbon Dioxide 100 % Decrease C 20C 30C Temperature % Carbon Dioxide Time Atmosphere

41 % Decrease of Metabolic Rate of Codling Moth Pupae Under Varying Concentrations of Oxygen 100 Time Temperature Atmosphere % decrease %O2

42 Metabolic heat rate at 20 C of a codling moth (C. pomonella) pupa, fresh mass g, in air and in a controlled atmosphere of 60% CO2 + N2. From: Downes et al

43 Response of green peach aphids ( (M. persicae) ) to anoxic atmospheres at 20 C, plotted as percent recovery of the initial metabolic heat rate in air, versus the time in the anoxic atmosphere. Downes et al

44 CATTS tu ra re Time e mp Te Controlled Atmosphere Temperature Treatment System sphere Atmo Controls & Monitors: O2, CO2, Air Speed, Humidity, Dew Point, Air Temperatures, Heat Rate, Fruit Temperatures (surface & core)

45 Combined Effects of Oxygen and Carbon Dioxide Levels To determine the critical levels of O2O and CO2 needed to make a heat treatment most effective. Used optimized CATTS treatment times of 45 min for 45 C and 25 min for 47 C (at 1%O2 and 15%CO2) as end points. 5 Levels of CO2 and 6 levels of O2. O 50 larvae per time point per rep. (4 reps).

46 3 rd 45 C, 20 min rd instar codling moth in sweet cherries % Corr. Mort % CO2 % O2

47 3 rd 45 C, 30 min rd instar codling moth in sweet cherries % Corr. Mort % O % CO2

48 3 rd 45 C, 40 min rd instar codling moth in sweet cherries % Corr. Mort % CO2 % O2

49 3 rd 47 C, 10 min rd instar codling moth in sweet cherries % Corr. Mort % CO2 % O2

50 3 rd 47 C, 15 min rd instar codling moth in sweet cherries % Corr. Mort % CO2 % O2

51 3 rd 47 C, 20 min rd instar codling moth in sweet cherries % Corr. Mort % CO2 % O2

52 Summary O /CO 2 Study 2 Low oxygen, between 0.5 and 1.0% proved to be most critical in providing efficacy. High levels of carbon dioxide, were less effective in causing mortality, but still necessary for treatment efficacy.

53 Making CA More Effective Time Temperature Atmosphere Heat shock before cold CA may protect commodity from chilling injury. Short heat treatment with CA can be very effective for disinfestations. Raising temperature a couple of C with low O 2 and elevated CO 2 can help. Lengthen duration of CA storage. Time Temperature Atmosphere

54 Summary Effects of physical treatments on insects is as varied as the treatments themselves. For many treatments, the affected systems are variable, and may depend on how scientists chose to look at the effects. The key to developing physical quarantine treatments is to pinpoint the physiological weakness of the insect or the physiological differences between the horticultural commodity and the infesting insect.

55 Goal for Development of Physical Postharvest Quarantine Treatments Zone of Opportunity Commodity Tolerance Insect Intolerance

56 Special Thanks! James Hansen Elizabeth Mitcham Krista Shellie Stan Ignatowicz Guy Hallman Jumming Tang Shaojin Wang Jim Mattheis

57 Positive proof that coatings do cause the formation of modified atmospheres in humans!