A new study of male honeybees shows that two insecticides, banned in some European nations but still used in the United States, can significantly reduce the bees' ability to reproduce. The study ... found that thiamethoxam and clothianidin, two chemicals from the neonicotinoid family of insecticides, reduce living sperm in male honeybees, called drones, by almost 40 percent. The effects of pesticides on honeybee populations are considered one culprit among several factors causing periodic declines. Neonicotinoids have been shown by other studies to harm the health of individual bees and the reproductive ability of female insects. The new study expanded on the dangers of the pesticides for males. The two neonicotinoids used in the study were banned in the European Union in 2013, but are used on an industrial scale in the United States. The Environmental Protection Agency ... will release risk assessments for the two chemicals, as well as another neonicotinoid, dinotefuran, in December. A significant amount of the global food supply is made up of plants that require pollinators like bees to survive. Any widespread threat to bees also constitutes a greater ecological threat. Beekeepers in the United States lost 44 percent of their honeybee colonies from April 2015 to April 2016, according to an annual survey conducted by the Bee Informed Partnership. The loss was 3.5 percent greater than that found from 2014 to 2015, when beekeepers lost 40.6 percent of colonies.