Required number of location-years for estimating functional lower developmental thresholds and required thermal summations of insects: The first emergence of adult Apthona nigriscutis Foudras as an example

Sampling theory was combined with resampling techniques to determine the number of location-years needed for estimating an insect's required thermal summation and lower developmental threshold from field-based studies. This was done by analysing 19 location-years of field observations on the first emergence of Apthona nigriscutis Foudras, an important biological control agent of the noxious weed, leafy spurge (Euphorbia esula L.). Results indicated that 5 - 7 location-years were needed to estimate that insect's mean required thermal summation and mean lower developmental threshold for predicting first adult emergence. However, if the wish was to estimate the median required thermal summation and median lower developmental threshold for that purpose, then 8 - 11 location-years were needed to obtain acceptable estimates of those parameters. The implications of these and other findings are discussed.