** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** LARGE BARK BEETLE OUTBREAKS HAVE OCCURRED ACROSS THE LANDSCAPE OF WESTERN NORTH AMERICA DURING THE PAST TWO DECADES WITH DRAMATIC ECOLOGICAL AND ECONOMIC IMPACTS FOR PUBLIC AND PRIVATE LANDS. THERE IS GROWING EVIDENCE THAT TREES ARE PREDISPOSED TO BARK BEETLE ATTACK BY ENVIRONMENTAL CONDITIONS, ESPECIALLY WATER STRESS. CONSEQUENTLY, REGIONAL DROUGHTS COULD SET THE STAGE FOR RAPID BEETLE POPULATION GROWTH THAT LEADS TO OUTBREAKS AND LARGE-SCALE FOREST MORTALITY. HOWEVER, IT REMAINS UNCLEAR EXACTLY WHY DROUGHT-STRESSED TREES BECOME MORE SUSCEPTIBLE TO BARK BEETLE ATTACK--ONE POSSIBILITY IS THAT DROUGHT STRESS INHIBITS THE ABILITY OF TREES TO DEFEND THEMSELVES. ALTHOUGH TREES DO NOT HAVE AN ADAPTIVE IMMUNE SYSTEM LIKE ANIMALS, MANY CONIFERS ARE ABLE TO RECOGNIZE AND RESPOND TO CELL DAMAGE FROM INSECTS BY PRODUCING TOXIC CHEMICALS IN THEIR RESIN. PRODUCTION OF THESE TOXINS ARE SIGNALED BY HORMONES THAT MAY BE FUNCTIONALLY IMPAIRED WHEN WATER STRESS OCCURS PRIOR TO BEETLE ATTACK. THE GOAL OF THIS WORK IS TO EXAMINE HOW DROUGHT STRESS INTERFERES WITH HORMONE PRODUCTION AND SENSITIVITY IN CONIFERS AND DETERMINE WHETHER THIS INTERFERENCE UNDERLIES PATTERNS OF FOREST MORTALITY ACROSS LANDSCAPES.