Temperature

Temperature

Temperature

One of most important density independent factors

Thermal death points for insects in general

Lower limits: -15 C (5 F)-- -30 C (-22 F)

Upper limits: 60 C (140 F)

F = 9/5C + 32

C = 5/9(F - 32)

Species Variation

Wide variation between species

Calliphora sp.

minimum activity temp: 4.4--15.6 F

No hatch: 4 C

Hatch: 6-7 C

Effect of Temperature

Calliphora Growth rate

Optimum range 18-30C

All species have upper and lower threshold

And optimum rage

Estimating Insect GrowthTemperature has direct bearing on estimating PMI

Based on “heat budget”

Each stage requires a given amount of heat above lower threshold and below upper threshold

The entire concept of PMI estimation is

based on the fact that insects are

temperature dependent

Degree Days & Degree HoursDegree Days

Total degrees of heat above lower threshold accumulated in one 24 hour period=Total Accumulated Degree Days

Degree Hours

Total degrees of heat above lower threshold accumulated in 60 minutes

(Average Temperature - Minimum Threshold) x Unit of TimeAccumulated Degree Days:

Average Temp. over 24 hours- Min thresholdx # of days

High: 90o FLow: 60o FMin: 55o F

2 DaysHow many accumulated degree days?

(Average Temperature - Minimum Threshold) x Unit of Time

Accumulated Degree Hours:

Average Temp. over 1 hour- Min thresholdx # of hours

High: 90o FLow: 60o FMin: 55o F

2 DaysHow many accumulated degree hours?

Estimating Insect Age

Experimentally figure out how much time each stage of development takes at a given temperature

Use information to calculate degree days

EggHrs

1st Insta

rHrs

2nd Insta

rHrs

3rd Insta

rHrs

PrepupaHrs

Pupa

Days

TotalDays

Sarcophaga cooley --- 24 18 48 96 9 16

Sarcophaga bullata --- 26 18 54 112 12 17

Phormia regina 16 18 11 36 84 6 11

Lucilia sericata 18 20 12 40 90 7 12

Calliphora vomitoria 26 24 48 60 360 14 23

Calliphora vicina 24 24 20 48 128 11 18

27 C

DD=(Max T + Min T/2) - lower threshold

Phormia regina 16 18 11 36 84 6 11

EggHrs

1st Insta

rHrs

2nd Insta

rHrs

3rd Insta

rHrs

PrepupaHrs

Pupa

Days

TotalDays

By convention: Lower threshold = 6 C

How many degree days, total, does Phormia regina require to go from egg to

adult at 27 C?

Evidence found on body

Phormia regina 16 18 11 36 84 6 11

EggHrs

1st Insta

rHrs

2nd Insta

rHrs

3rd Insta

rHrs

PrepupaHrs

Pupa

Days

TotalDays

What is the minimum amount of time this casing has been there?

Evidence found on body

Phormia regina 16 18 11 36 84 6 11

EggHrs

1st Insta

rHrs

2nd Insta

rHrs

3rd Insta

rHrs

PrepupaHrs

Pupa

Days

TotalDays

What is the minimum amount of time these maggots have been there?

Date MinoF MaxoF DD ADDMarch

2145 74

March 22

51 78

March 23

49 70

March 24

43 67

March 25

47 74

March 26

58 78

March 27

64 82

(Average Temperature - Minimum Threshold) x Unit of Time

Minimum Threshold: 45oF

Homework: (Worth 2 quizzes--10 points)

Under “Handouts” on the websiteDue by Friday, April 11th

Any Questions?