Conditional lethal release is a variation of the sterile insect technique(SIT)for the biological control of pest insects resulting from the release of transgenic insects carrying dominant conditional lethal genes.We have taken two approaches towards conditional lethal release including use of a dominant temperature-sensitive(DTS)mutation,and a tetracycline(tet)-suppressible embryonic lethality system.For DTS lethality,a heat-sensitive mutation in the proteasome subunit gene,Prosβ2,first described in Drosophila melanogaster as DTS-7,was used.