Some of the above confusion stems from confusion over the word "hive",. A hive is a human-made container that houses a colony of bees-- honey bees, stingless bees in the tropics, or in this case bumblebees. Growers do purchase hives of bumblebees for pollination of tomatoes, peppers, and other crops in greenhouses, and less frequently outdoors.
The commercial hive contained colonies of Bombus impatiens, the most common bumblebee species in eastern N. America. All but one of the invading queens that were killed inside the hives were of the same species- B. impatiens. This is NORMAL behavior in nature. Good nesting sites (like abandoned mouse nests) are in short supply and queens in spring fight and kill each other to obtain a good nest. There was only one other dead queen in a hive. It was Bombus perplexus, also a free-living (not a parasitic) bumblebee species.
Most confusing for me was the photo of a honey bee hive labelled "worker bees entering a commercial hive". Terrible choice of photo, LiveScience! Totally unrelated to the article, about bumblebees.