A new study by Purdue University reveals that rising levels of CO₂ are impacting North American bees , by reducing protein in goldenrod pollen , their primary late - season food source : " A poor diet sets bees up for extinction , " says Jeffery Pettis of the US Department of Agriculture 's Research Service , adding that " previous research shows bees have shorter lifespans when fed lower quality pollen . Pollen is essential for the development of bee larvae and helps maintain bees' immunity to pathogens and parasites. " As we have highlighted , bees gain over $ 1 in added crop value in the US each year through pollination , however the US Agriculture Department said that 42 % of US honeybee colonies died in the 12 months ending April 2015 . Recent studies already show that higher CO2 reduce the nutritional value of plants including global food staples such as rice and wheat .
A new study by Purdue University reveals that rising levels of CO₂ are impacting North American bees , by reducing protein in goldenrod pollen , their primary late - season food source : " A poor diet sets bees up for extinction , " says Jeffery Pettis of the US Department of Agriculture 's Research Service , adding that " previous research shows bees have shorter lifespans when fed lower quality pollen . " As we have highlighted , bees gain over $ 1 in added crop value in the US each year through pollination , however the US Agriculture Department said that 42 % of US honeybee colonies died in the 12 months ending April 2015 . Recent studies already show that higher CO2 reduce the nutritional value of plants including global food staples such as rice and wheat .