THE DEVELOPMENT OF LIFE TABLES FOR THE SPRUCE BUDWORM

Abstract

A method for preparing life tables is described and two examples are presented, based on field data from the Green River Watershed in northwestern New Brunswick. Column headings for age interval (x), survivorship (lx), deaths (dx), and death rate (qx) are adopted from human life tables. An additional column, dx factor, should be added to insect life tables so that the different mortality factors can be tabulated. Life tables for the spruce budworm are based on intensive population sampling on permanent plots, complemented by data on fecundity, natural and applied control factors, and dispersion. Techniques for these basic studies will be detailed in subsequent papers. Life tables for consecutive generations of the budworm in different forest types should provide fundamental information on the epidemiology of the species and on the possible reduction of damage through forest management and through direct control measures.