THE STERILE INSECT TECHNIQUE (SIT) IS A BIOLOGICALLY-BASED STRATEGY THAT PROVIDES THE MOST ECOLOGICALLY SOUND MEANS FOR SUPPRESSION OF INSECT PEST POPULATIONS. MANY CURRENT PROGRAMS, HOWEVER, ARE INEFFICIENT DUE TO THE INABILITY TO ELIMINATE FEMALES BEFORE MALE RELEASE, AND THE DEBILITATING EFFECTS OF RADIATION USED TO STERILIZE MALES. GENETIC MANIPULATION OF SPECIES SUBJECT TO SIT NOW ALLOWS THE USE OF TRANSGENIC AND GENE-EDITING STRATEGIES TO OVERCOME BOTH LIMITATIONS. OUR GOAL IS TO DEVELOP NEW TRANSGENIC STRAINS FOR THE FRUIT FLY PESTS, ANASTREPHA LUDENS AND DROSOPHILA SUZUKII, FOR TETRACYCLINE-SUPPRESSIBLE (TET-OFF) FEMALE-SPECIFIC EMBRYONIC LETHALITY FOR SEXING, AND SPERMATOCYTE-SPECIFIC LETHALITY FOR MALE GONADAL STERILITY. IN COMBINATION, EMBRYOS REARED ON A TET-FREE DIET SHOULD RESULT IN MALE-ONLY STERILE SURVIVORS FOR RELEASE. A SECOND STRATEGY IS THE USE OF CRISPR/CAS9 GENE-EDITING TO REPLACE WILD TYPE ALLELES OF THE TRANSFORMER-2 (TRA-2) SEX-DETERMINATION GENE, NECESSARY FOR FEMALE SEX-SPECIFIC DIFFERENTIATION, WITH TEMPERATURE-SENSITIVE MUTANT ALLELES (TRA-2TS). BASED ON D. MELANOGASTER STUDIES, TRA-2TS INDIVIDUALS FROM D. SUZUKII AND A. SUSPENSA SHOULD DEVELOP AS NORMAL FERTILE ADULTS AT 18C, BUT AT 29C, BOTH CHROMOSOMAL XY MALES AND XX FEMALES SHOULD DEVELOP AS PHENOTYPIC MALES, THAT ARE ALSO STERILE IN D. SUZUKII. IN A. SUSPENSA, ONLY XX; TRA-2TS MALES SHOULD BE STERILE SINCE TRA-2 DOES NOT HAVE AN APPARENT GERM-LINE FUNCTION IN XY MALES, THOUGH STERILITY MAY BE ACHIEVED BY INTEGRATING TET-OFF SPERMATOCYTE-LETHALITY. THESE STUDIES SHOULD RESULT IN HIGHLY EFFICIENT, COST EFFECTIVE AND ENVIRONMENTALLY SAFE METHODS FOR IMPROVED SIT, THAT ADDRESSES THE PRIORITY AREA OF FUNDAMENTAL RESEARCH THAT LEADS TO BIOLOGICALLY-BASED APPROACHES TO MANAGING INSECT PEST POPULATIONS.