Population Response of Twelve Species of Insects following Exposure to Ionizing Radiation1,2

Abstract

Samples of insects representing 10 genera in 2 orders, Lepidoptera and Orthoptera, were exposed to 15,000 rad of gamma radiation from a Cobalt-60 source. The population response of these species was then studied using life tables as an evaluative aid. Mean life expectancy of the 0–1 age class of specimens of 6 species of irradiated Lepidoptera decreased 7–33% from that of the control, depending on the species. However, life expectancies of 6 Orthoptera were reduced by about 90%, in most cases, following radiation exposure. Treated moth populations of all age groups had lowered life expectancies as well as a reduction in the number of age classes. Periplaneta americana (L.) was the most radiosensitive orthopteran studied and Cadra cautella (Walker) the most sensitive lepidopteran. Supella longipalpa (F.) was the most resistant orthopteran species studied and Plodia interpunctella (Hubner) the most resistant lepidopteran. Agespecific mortality rates of treated populations increased with age at a faster rate than did mortality rates of control groups in the species studied.