 This is the VOA Special English Agriculture Report. Bees add an estimated $18 billion a year to the value of American crops. They pollinate flowers that become fruits, nuts, and vegetables. But in recent years, honeybee colonies in the United States and Europe have been shrinking. Scientists have proposed different theories to explain what is known as Colony Collapse Disorder. New research suggests that a commonly used group of insecticides could cause bees to have a hard time finding their way back to their hive. The new research looks at the use of pesticides called neonicotinoids. They were first used in the 1990s. They are now put on the seeds of many major crops around the world. The seedlings absorb the chemical as they grow. That means farmers do not need to spray a whole field. Instead, there is a little bit of insecticide inside each plant, including the pollen and nectar that the bees want. There is not enough pesticide to kill them. But the new research in the Journal of Science says it may harm them anyway. Researchers stuck microchips to the backs of the bees. These chips recorded the bees' movements as they came and went from their hive. The scientists fed some bees sugar water with the low dose of a neonicotinoid. The study found that these bees were about twice as likely not to return as other bees. Miquel Henri from INRA, the French National Agriculture Research Institute, says the bees basically get drunk. He says, intoxicated honeybees with those small doses may just get lost and are not able to find their way back home. For some crops around the world, wild pollinators like bumblebees are more important than honeybees. Dave Gulson at the University of Stirling in Britain worked on another study in science. He says the pesticides could help explain why bumblebee populations are also decreasing. He says there were 85% fewer queens produced than when they had been exposed to what he called realistic field levels. Bear crop science makes neonicotinoid pesticides. Company spokesman Jack Boyne disputed the findings. He says the authors dozed the bees at levels far greater than what would commonly be experienced in the field. He also notes that researchers are studying other factors that could affect bee populations. Some European countries have banned the pesticides and there are growing calls to ban them in the United States as well. For VOA Special English, I'm Carolyn Presuti.