**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** TEPHRITID FRUIT FLIES REPRESENT SOME OF THE MOST DESTRUCTIVE PESTS OF SOFT FRUITS AND VEGETABLES WORLDWIDE. THE HAWAIIAN ISLANDS, IN PARTICULAR, HAVE SUFFERED FROM INVASIVE FLY DAMAGES TO COMMERCIAL FRUIT PRODUCTION FOR OVER A CENTURY, AND BIOLOGICAL CONTROL EFFORTS ARE A LARGE PRIORITY FOR THE CONTROL OF THESE AGRICULTURAL PESTS. ONE OF THE MOST SUCCESSFUL CASES OF BIOLOGICAL CONTROL ON HAWAII HAS BEEN THE RELEASE OF THE PARASITOID WASP FOPIUS ARISANUS TO SUPPRESS DESTRUCTIVE FRUIT FLY POPULATIONS. F. ARISANUS IS ONE OF FEW FRUIT FLY PARASITOID SPECIES THAT HAS BECOME ESTABLISHED ON THE ISLANDS AND IS THE DOMINANT WASP SPECIES FOUND TO PARASITIZE SEVERAL MAJOR FRUIT FLY PESTS. WHILE THE GENERAL BIOLOGY, ECOLOGY, AND BEHAVIOR OF F. ARISANUS HAS BEEN WELL STUDIED, THERE IS A FUNDAMENTAL GAP IN KNOWLEDGE PERTAINING TO THE MOLECULAR DYNAMICS BETWEEN F. ARISANUS AND ITS FRUIT FLY HOSTS THAT LEAD TO PROLIFIC PARASITISM RATES BY THIS WASP AT THE EXPENSE OF FLY SURVIVAL. RECENT SEQUENCING OF THE F. ARISANUS GENOME REVEALED SEVERAL CLUSTERS OF VIRAL GENES DISPERSED THROUGHOUT THAT WERE LATER DEMONSTRATED TO PRODUCE HIGH DENSITIES OF VIRUS-LIKE PARTICLES (VLPS) WITHIN THE OVARIES OF FEMALE WASPS. THIS DISCOVERY IS THE MOST RECENT OF SEVERAL KNOWN VIRAL ELEMENTS PRODUCED BY AGRICULTURALLY IMPORTANT PARASITOID WASP LINEAGES. OTHER HERITABLE PARASITOID VIRUSES PROVIDE A HIGHLY BENEFICIAL FUNCTION FOR THE WASPS THAT PRODUCE THEM BY MANIPULATING THE PHYSIOLOGY OF THE HOST INSECT. IN THIS PROJECT, I WILL USE A COMBINATION OF MOLECULAR BIOLOGY, MANIPULATIVE GENETICS, AND GENOMIC SEQUENCING TECHNIQUES TO CHARACTERIZE THE FUNCTION OF F. ARISANUS VLPS AND INVESTIGATE THE GENETIC UNDERPINNINGS THAT FACILITATE VLP FUNCTION WITHIN FRUIT FLY HOSTS. UNDERSTANDING MOLECULAR FACTORS, SUCH AS VLPS, THAT LIKELY CONTRIBUTE TO FRUIT FLY IMPAIRMENT DURING PARASITISM WILL PROVIDE NOVEL AVENUES FOR FUTURE BIOLOGICAL CONTROL INITIATIVES AGAINST FRUIT FLY PESTS.