[en] A laboratory study was carried out in egypt to determine the effect of combining treatments of gamma radiation and methyl bromide fumigation applied to to adults of tribolium confusum (D uv.) An interaction between radiation and insecticidal treatment was obvious, with additive effects noted at most combination treatments. When radiation treatments were applied first and followed by fumigation within 24 hr, very low dosages of radiation (2-6 krad) decreased the susceptibility of the insects to marginally effective dosages of methyl bromide after 14 days. Irradiation pretreatment followed by fumigation after 21 days enhanced the fumigant effectiveness. Irradiation treatments using dosages from 5-50 krad followed by fumigant treatments after 7 days killed more insects than did either treatment applied alone. When sublethal dosages of fumigation preceded irradiation, the insects became more radio-sensitive. In general, the effects of irradiation and fumigation combinations were higher than the effects of either treatment given singly, irrespective which treatment was given first. 3 tab