The sensitivity of scale insects to 14 C -particles and to 60 CO gamma rays.

Abstract

SummaryThe concentrations of 14C which can be tolerated by the scale insect Aonidiella aurantii (Mask) throughout its development have been investigated.Dose-survival curves show the activity of 14C in insects in relation to the survival of first instar larvae, the emergence of winged males and the reproduction of females. The 50 per cent survival values, in terms of the concentrations of 14C in the insects at these stages, were about 680 µCi gm−1, 360 µCi gm−1 and 24 µCi gm−1, respectively. Calculations of the equivalent dose-rates from β-particles are attempted.The sensitivity to 60Co γ-rays of insects of various ages was studied. Dose-survival curves show that irradiation prior to moulting is about three times as effective as irradiation during moulting, and that irradiation at an early age has an effect on later development. These findings were used in calculating the cumulative doses from 14C.At the 50 per cent survival level, the cumulative dose from 14C, adjusted for changes in sensitivity with time, was estimated to be about 7600 rads for first instar larvae, 9800 rads for emerging males and 4200 rads for reproduction in females. These values are about three times the minimum γ-ray doses which produced similar effects.