Mortality and Abnormalities Caused by Gamma Irradiation of Alfalfa Weevil Larvae1

The effects of gamma radiation on 3rd- and 4th-stage larvae of the alfalfa weevil, Hypera postica (Gyllenhal) (Coleoptera: Curculionidae), were studied. The 3rd-stage larvae were irradiated at 2–10 kiloröntgens (kR). Mortality was almost 100% at all radiation levels. The few specimens that pupated died in the pupal stage. Fourthstage larvae were irradiated at 0.5–10 kR. The 4th-stage larvae were not as adversely affected as the 3rd-stage larvae. However, when the surviving 4th-stage larvae became pupae, mortality increased to 100% (at the 4-kR and higher rates). Specimens that emerged after radiation at lower levels had abnormal antennae, legs, and elytra.