Effects of chronic gamma radiation on populations of Ips (Coleoptera: Scolytidae) in trap logs

Abstract. 1. Population dynamics of Ips calligraphus and I. grandicollis (Coleoptera: Scolytidae) were studied in a forest exposed to high doses of gamma radiation.
2. Populations were replicated at eleven dose rates by using 'trap logs'.
3. Adult beetles did not avoid high radiation intensities and attacked all sites equally.
4. Utilization of the cambium-inner bark area varied from c. 2% at a dose rate of 2520 R/20 h day to 90% at dose rates of 63 and 105 R/20 h day.
5. Developmental success of the new brood was directly dependent on the dose rate, and developing progeny were often killed by accumulated exposure.
6. Larger, slower developing species of subcortical beetles were eliminated at dose levels that allowed successful development of the two species of Ips bark beetles.