Gamma Irradiation of the European Chafer. 1. Irradiation of Third-Stadial Larvae, with Observations on Spermatogenesis

Gamma irradiation levels for LD50 values on 3rd-stadial larvae of Amphimallon majalis (Razoumowsky) were 3300 rad (3.3 krad) for fall-collected individuals and 7.1 krad for spring-collected individuals when exposed as mature 3rd-stadial grubs approaching the prepupal stage. Serial sections of grubs exposed to doses of 0.5 to 50 krad all showed visible cytological injury to the germinal cells with pyenotic nuclei present in the treated testicular follicle. Male 3rd-stadial grubs were consistently more susceptible to gamma irradiation than females; exposure to 1 krad in the former produced comparable effects in emergence as 2.5 krad in the latter. Both male and female adults emerging from grubs treated at 2.5 had had deformed wings. Grubs exposed to lower doses produced beetles with slightly shorter elytra than adults from nonirradiated grubs. Dose requirement for completely sterilizing larvae was higher than that for completely inhibiting metamorphosis.