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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. - PowerPoint PPT Presentation
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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?
