Effects of gamma radiation on mortality and sterility of some storedproduct beetles

M. A. Rahim and Y. Norimah

Abstract

The effects of gamma radiation on mortality and sterility of five species of beetles in a stored product were studied. The dosages used ranged from 0.05 kGy to 1.0 kGy. Complete sterilization was achieved at 1.0 kGy for Lasioderma serricone and Oryzaephilus surinamemensis and at 0.05 kGy for Tribolium castaneum. For Sitophilus zeamais and Rhizopertha dominica, more than 93% reduction of F_t progenics was observed with random variations among all the tested dosage levels. Irradiation of male S. zeamais adults showed that insect control by male sterility technique is not effective. Developing S. zeamais larvae in rice kernels were completely killed either within the kernel or after emergence as adults at all the tested dosages. However. 0.6% to 1% of the treated larvae within the kernels managed to complete their development into adults with the number of emergent inversely proportional to the dosage levels. Complete mortality of the treated adults of all storage beetle species tested was obtained after 4 - 7 weeks below 0.2 kGy and 1-3 weeks above 0.2 kGy.

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