Published online by Cambridge University Press: 31 May 2012
Regression coefficients derived from the Nicholson–Bailey parasite mode) by Hassell and Huffaker (1969) are interpreted, and their conclusions about the biological significance of changes in slope are shown to be invalid. It is demonstrated that the term "delayed density-dependence" has no functional significance because it includes density responses that range from inverse to direct, depending upon the particular theoretical model that is selected for simulation exercises. In natural populations of a number of forest insects, the net response of parasitism to host density is direct, not inverse.