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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.

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Presentation on theme: "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."— Presentation transcript:

1 Temperature

2 One of most important density independent factors Thermal death points for insects in general Lower limits: -15 C (5 F) C (-22 F) Upper limits: 60 C (140 F) F = 9/5C + 32 C = 5/9(F - 32)

3 Species Variation Wide variation between species Calliphora sp. minimum activity temp: F No hatch: 4 C Hatch: 6-7 C

4 Effect of Temperature Calliphora Growth rate Optimum range 18-30C All species have upper and lower threshold And optimum rage

5 Estimating Insect Growth Temperature 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

6 The entire concept of PMI estimation is based on the fact that insects are temperature dependent

7 Degree Days & Degree Hours Degree 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

8 (Average Temperature - Minimum Threshold) x Unit of Time Accumulated Degree Days: Average Temp. over 24 hours- Min thresholdx # of days High: 90 o F Low: 60 o F Min: 55 o F 2 Days How many accumulated degree days?

9 (Average Temperature - Minimum Threshold) x Unit of Time Accumulated Degree Hours: Average Temp. over 1 hour- Min thresholdx # of hours High: 90 o F Low: 60 o F Min: 55 o F 2 Days How many accumulated degree hours?

10 Estimating Insect Age Experimentally figure out how much time each stage of development takes at a given temperature Use information to calculate degree days

11 Egg Hrs 1st Instar Hrs 2nd Instar Hrs 3rd Instar Hrs Prepu pa Hrs Pup a Day s Total Days Sarcophaga cooley Sarcophaga bullata Phormia regina Lucilia sericata Calliphora vomitoria Calliphora vicina C

12 DD=(Max T + Min T/2) - lower threshold Phormia regina Egg Hrs 1st Instar Hrs 2nd Instar Hrs 3rd Instar Hrs Prepu pa Hrs Pup a Day s Total Days By convention: Lower threshold = 6 C How many degree days, total, does Phormia regina require to go from egg to adult at 27 C?

13 Evidence found on body Phormia regina Egg Hrs 1st Instar Hrs 2nd Instar Hrs 3rd Instar Hrs Prepu pa Hrs Pup a Day s Total Days What is the minimum amount of time this casing has been there?

14 Evidence found on body Phormia regina Egg Hrs 1st Instar Hrs 2nd Instar Hrs 3rd Instar Hrs Prepu pa Hrs Pup a Day s Total Days What is the minimum amount of time these maggots have been there?

15 DateMin o FMax o FDDADD March March March March March March March (Average Temperature - Minimum Threshold) x Unit of Time Minimum Threshold: 45 o F

16 Homework: (Worth 2 quizzes--10 points) Under “Handouts” on the website Due by Friday, April 11th

17 Any Questions?


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