The modernization of agriculture and demand for crops to feed the human population has brought about a significant increase in pesticide use. This has an adverse effect on the genus Bombus. The bees are directly exposed to the chemicals in two ways: by consuming nectar that has been directly treated with pesticide, or through physical contact with treated plants and flowers. Pesticides can impact the B. hortorum colonies by reducing brood development and also impairs their memory, preventing them from remembering the locations of their foraging sites and nests. Furthermore, when a single queen is first establishing her colony at the beginning of the season, pesticide risks could pose consequences for colony development and size.
