**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** THE NEW WORLD SCREWWORM, COCHLIOMYIA HOMINIVORAX, IS A MAJOR PEST OF LIVESTOCK. CURRENTLY FOUND ONLY IN SOUTH AMERICA AND A FEW CENTRAL AMERICAN COUNTRIES, THE SCREWWORM COSTS FARMERS IN THESE REGIONS MORE THAN $3 BILLION/YEAR IN DAMAGE.ALTHOUGH IT WASERADICATED FROM THE UNITED STATES, SCREWWORM OUTBREAKS HAVE OCCURRED HERE (AND IN OTHER COUNTRIES), AND THE SCREWWORM REMAINS A THREAT TO US AGRICULTURE AND WILDLIFE. SCREWWORM OUTBREAKS ARE CONTROLLED USING THE STERILE INSECT TECHNIQUE, WHERE LARGE NUMBERS OF MALES ARE PRODUCED, STERILIZED, AND RELEASED INTO THE WILD, CRASHING THE POPULATION. THE STERILE INSECT TECHNIQUE IS ECO-FRIENDLY AND EFFECTIVE, BUT IT COULD BE DRAMATICALLY IMPROVED IF FEMALE SCREWWORMS COULD SOMEHOW BE TURNED INTO MALES; THIS WOULD DOUBLE THE PRODUCTION RATE OF MALE SCREWWORMS, AND WOULD ELIMINATE THE NEED TO SEPARATE MALES AND FEMALES BEFORE RELEASING THE MALES.THE GOAL OF THIS PROJECT IS TO DEVELOP A FEMALE-TO-MALE SEX TRANSFORMATION SYSTEM IN LUCILIA CUPRINA, A MODEL ORGANISM THAT IS CLOSELY RELATED TO THE SCREWWORM. TO BUILD THIS SYSTEM, I WILL DESIGN AN ARTIFICAL DNA SEQUENCE THAT BLOCKS THEFEMALENESS GENE IN LUCILIA CUPRINA.I WILL INJECT THIS DNA SEQUENCE INTO LUCILIA CUPRINA EGGS SO THAT THE DNA CAN BE INSERTED INTO THE GENOME. AFTER CHECKING THAT THE DNA SEQUENCE WAS SUCCESSFULLY INSERTED, I WILL SEE WHETHER FEMALES ARE BEING TRANSFORMED INTO MALES BY EXAMINING THE GENITALIA OF THESE INSECTS. I WILL ALSO TEST WHETHER THESE INDIVIDUALS ARE HEALTHY BASED ON EGG HATCHING RATES AND MORTALITY RATES. I WILL KEEP 3 LINES WITH THE HEALTHIEST INDIVIDUALS AND THE BEST SEX TRANSFORMATION RATES. I WILL THEN PERFORM ADDITIONAL TESTS TO SEE WHETHER FEMALES THAT HAVE BEEN TRANSFORMED INTO MALES WILL ATTEMPT TO MATE WITH NORMAL (UN-TRANSFORMED) FEMALES. IF SO, THIS MEANS THAT THE TRANSFORMED MALES AREBEHAVING LIKE NORMAL MALES, AND COULD BE USED FOR THE STERILE INSECT TECHNIQUE. FINALLY, I WILL TEST WHETHER THE SEX TRANSFORMATION SYSTEM CAN BE TURNED OFF WITH TETRACYCLINE. I EXPECT THAT TETRACYCLINESHOULD TURN THE SYSTEM OFF AND GIVE US BOTH MALES AND FEMALES, WHICH IS USEFUL FOR BREEDING AND LONG-TERM LINE MAINTENANCE.IF THE FEMALE-TO-MALE SEX TRANSFORMATION SYSTEM WORKS IN LUCILIA CUPRINA, THE NEXT STEP WOULD BE TO PORT IT TO THE SCREWWORM AND TEST THE SYSTEM IN THIS SPECIES. IF SEX TRANSFORMATION WORKS IN THE SCREWWORM, SCREWWORM CONTROL WOULD BECOME MUCH MORE EFFICIENT, SINCE THE YIELD OF MALES COULD DOUBLE AND SEX-SORTING WOULD NO LONGER BE NEEDED. THIS IMPROVED EFFICIENCY WOULD TRANSLATE INTO LOWER PRODUCTION COSTS, AN ABILITY TO RAPIDLY SCALE UP PRODUCTION IN RESPONSE TO SCREWWORM OUTBREAKS, AND, ULTIMATELY, IMPROVED ANIMAL AND HUMAN HEALTH AND ECONOMIC SECURITY.