**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** THIS PROJECT SEEKS TO UNDERSTAND MECHANISMS BY WHICH THE LAUREL WILT PATHOGEN HARRINGTONIA LAURICOLA, FORMS ASSOCIATIONS WITH ITS BEETLE HOST. LAUREL WILT IS A DEVASTATING PLANT DISEASE AFFECTING MEMBERS OF THE LAURACEAE FAMILY THAT INCLUDES THE ECONOMICALLY IMPORTANT AGRICULTURAL CROP, AVOCADO. THE FUNGUS IS BROUGHT TO HOST TRESS BY ITS BEETLE PARTNER, WHICH CULTIVATES THE FUNGUS WITHIN GALLERIES INSIDE THE TREE AS THEIR FOOD SOURCE. WHILE MOST SUCH BEETLE-FUNGAL PARTNERS DO NOT CAUSE DISEASE, H. LAURICOLA, IS AN INVASIVE SPECIES, AND HAS PROVEN TO BE LETHAL EVEN TO HEALTHY TREES. THE FUNGUS IS CARRIED BY THE BEETLE TO HOST TREES IN SMALL STRUCTURES TERMED MYCANGIA, THAT HOUSE LIVING FUNGAL CELLS THAT THE BEETLE USES TO INOCULATED AND GROW THEIR FUNGAL FOOD. THIS PROJECT SEEKS TO BEGIN TO ADDRESS HOW THE FUNGUS COLONIZES THE MYCANGIA, AND THE EXTENT TO WHICH IT IS PRESERVED AND/OR TURNED OVER IN THE MYCANGIA. RESULTS FROM THE PROJECT WILL HELP DEFINE THE PHYSIOLOGY AND GENETICS OF FUNGI THAT ARE MUTUALISTS OF INSECTS, AND HOW THIS ASSOCIATION OCCURS.