A new study has found that climate change may drive local extinction of mason bees in Arizona and other naturally warm climates. In a two-year field experiment that altered the temperature of the bees' nests to simulate a warmer, future climate, 35 percent of bees died in the first year and 70 percent died in the second year. This is compared to a 1 to 2 percent mortality rate in the control group. This species of mason bee (pictured) often called the "blueberry mason bee," is native to the western United States and northern Mexico. This particular type of solitary bee builds nests inside of holes and cracks in dead tree stumps. As a primary pollinator of manzanita shrubs in the wild, this little-studied bee may have a big effect on its ecosystem. To study how climate change affects mason bees, the research team set up three types of nesting environments in Arizona's Santa Catalina Mountains (above), where the bees thrive. The team manipulated the temperatures of the nests by painting them to simulate past, present and future climates. The team painted a third of the nests black to absorb more radiant heat, thus simulating a future climate predicted for the years 2040 to 2099. By painting another third with a white, reflective, cooling treatment, the team sent that third of the nests back in time to a climate similar to that of the 1950s. As a control, the team painted the final nests with a transparent paint, leaving their natural wood color. The experiment included 90 nests total, each housing anywhere from 2 to 15 bees.
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