8.3. How to measure temperature?Yes, use a thermometer! The only problem is when and where to measure it. The simplest way is to measure minimum and maximum temperatures each day and then take the average. Majority of weather data bases contain minimum and maximum temperatures. More accurate estimates can be obtained if temperature was measured several times a day at regular intervals (e.g. every 3 h). Then, you can average these measures.
The next problem is where to measure. It is obvious, that temperature should be measured where studied organisms are located. For example, if we study development of soil insects [e.g., wireworms (Elateridae)], then temperature should be measured in the soil at ca. 5-10 cm from the surface. Spider mites live on the lower leaf surface where temperature is several degrees lower than the ambient temperature. In this case, temperature should be measured under the leaf. Some times it is possible to build a regression model that predicts the temperature in a specific niche from ambient temperature recorded at weather stations.
Can we average temperature prior to analysis?If development rate is a linear function of temperature, then temperature can be averaged prior to analysis. However, if this function is non-linear (e.g., in the improved degree-day model, see below), then temperature averaging may result in substantial errors.