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Published byAndrew Sennett Modified over 2 years ago

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Temperature

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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)

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Species Variation Wide variation between species Calliphora sp. minimum activity temp: 4.4--15.6 F No hatch: 4 C Hatch: 6-7 C

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

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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

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

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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

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(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?

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(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?

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

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Egg Hrs 1st Instar Hrs 2nd Instar Hrs 3rd Instar Hrs Prepu pa Hrs Pup a Day s Total Days Sarcophaga cooley ---24184896916 Sarcophaga bullata ---2618541121217 Phormia regina 1618113684611 Lucilia sericata 1820124090712 Calliphora vomitoria 262448603601423 Calliphora vicina 24 20481281118 27 C

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DD=(Max T + Min T/2) - lower threshold Phormia regina 1618113684611 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?

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Evidence found on body Phormia regina 1618113684611 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?

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Evidence found on body Phormia regina 1618113684611 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?

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DateMin o FMax o FDDADD March 214574 March 225178 March 234970 March 244367 March 254774 March 265878 March 276482 (Average Temperature - Minimum Threshold) x Unit of Time Minimum Threshold: 45 o F

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

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Any Questions?

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