Study also finds that crop yields are often limited by a lack of pollinators. A new study finds that the yields of major crops in the United States are frequentlylimited by a lack of pollinators. The study also highlighted the value of America’s wild bees, estimating they boost yields for six of the country’s seven major cropsexamined in … More Wild Bees Are Worth $1.5 Billion for Six U.S. Crops.