Prediction of Variation in Development Period of Insects and Mites Reared at Constant Temperatures1

Abstract

The relationship of standard deviation (SD) of developmental period at constant temperatures to mean developmental period ($\bar x$) was examined based on data for 113 species of insects and mites. The regression equation SD = 0.209 $\bar x$0.730 explained 65% of the variance of SD; this relationship differed little between insects and mites, and varied little among the orders of insects. This relationship is useful for designing constant-temperature rearing experiments for insects and mites. A standard protocol for presenting results of these experiments is suggested. The regression equation is also useful in developing stochastic models of insect development at varying temperatures. Transformations are presented for converting statistics based on developmental period to statistics for developmental rate. Statistics on rate of development computed from these transformations were used to test the prediction that coefficient of variation of developmental rate should be constant. This prediction did not hold for about 20% of the 194 cases for which it was tested, so the underlying hypothesis, that variation in concentration of rate-controlling enzymes among individuals explains variation in developmental rate, must be rejected.