Simple Estimation of Intrinsic Increase Rates for Aphids and Tetranychid Mites

Abstract

A simplified method for the estimation of the intrinsic rate of natural increase (rm) of aphids is proposed. Having determined the prereproductive time, d (birth to first reproduction), the number of progeny (Md) produced in an equal time is observed and the rm is calculated from the equation: rm = 0 74 (logeMd)/d. The accuracy of the method is tested by reference to the life table data for four aphids under eight sets of environmental conditions (Wyatt & Brown 1977) and by comparison with other published data. The method has been shown to be equally applicable to tetranychid mites, by reference to published data. It is suggested that a reasonably accurate estimate of generation time is provided by the value 4d/3.