This violent death of the queen seems to be the natural end of the colony. The temperature drops under the needed temperature of 32 degree Celsius and the workers die. The young, mated queens survive wintertime hidden in earth or under straw. Bumblebees are doing Honey like Honeybees. They gather nectar which got thickened and fermented, which means, the sugars got changed by enzymes.
Honey is long-term storable and contains mainly carbonhydrates as sugars.
Only adult Bumlblebees feed from Honey, the larvae get proteinic pollen. They shatter the flowers by using their wing musceles so they got covered with pollen. Bumblebees are the most important fertilizers of fruit trees and clover and they are not replacable by other bees. Honeybees 'dance' to attract other bees. They show the direction and distance of the found flowers.