Final answer:
The ADD for the 2nd instar of Calliphora stygia is 3437.5 degree days, using the 275-hour development rate and a temperature difference of 12.5°C. The ADH is the same value in degree hours, 3437.5, as it is calculated without converting the hours into days.
Step-by-step explanation:
To determine the Accumulated Degree Days (ADD) for the 2nd instar of Calliphora stygia, you need to use the average temperature at which the species develops, subtract the base temperature threshold, and then multiply by the number of hours to pass through that instar.
Given that the development rate from the 2nd instar to the 3rd instar is 275 hours at an average temperature of 14.5°C, and the base temperature threshold is 2°C, we first calculate the temperature difference (14.5°C - 2°C = 12.5°C), and then multiply this by the number of development hours (12.5 x 275 hours) to get the ADD.
The Accumulated Degree Hours (ADH) can be calculated similarly but is measured in hours rather than days. Using the same temperature difference and development hours, we simply don't convert the hours into days for ADH. Thus, ADH equals the temperature difference multiplied by the hours taken for the development of the 2nd instar to the 3rd instar.
The ADD would be 3437.5 degree days (12.5°C x 275 hours), and the ADH would be 3437.5 degree hours, as the calculation does not involve a conversion into days.