@natgeo This is what corn seed looks like when it is treated with the neonicotinoid pesticide Chlothianidin. Each color indicates a different concentration of the pesticide. Neonicotinoids have been getting a lot of scrutiny lately because they have been found to be very harmful to honeybees. For example, one of the purple corn seeds shown here has enough pesticide to kill 100,000 bees if they came in direct contact with it. The tricky part is, bees typically don’t come in direct contact with treated seed since they are planted directly underground. Instead, the pesticide penetrates the seed and becomes incorporated into all of the plant’s tissue. So bees come into contact with low doses over longer periods of time as they collect contaminated pollen. In the lab, low doses have been shown to kill honeybee larvae and affect their navigation abilities. However, it is harder to prove what is going on out in the field. On top of that, neonicotinoids were designed to replace older pesticides that were more harmful to humans and other vertebrates. So it turns into a complicated trade-off when it comes to regulating these chemicals. Photographed by Anand Varma (@anandavarma) for the honeybee story in the May 2015 issue of @natgeo. A lot of Australian farmers and Gardeners use this stuff. Please don't use Confidor. Imidacloprid is a nicotine-derived systemic insecticide, belonging to a group of pesticides called neonicotinoids. Although it is off patent, the primary producer of imidacloprid is the German chemical firm Bayer CropScience. The trade names for imidacloprid include Gaucho, Admire, Merit, Advantage, Confidor, Provado, and Winner. Imidacloprid is a neurotoxin that is selectively toxic to insects relative to vertebrates and most non-insect invertebrates. It acts as an agonist on the postsynaptic nicotinic acetylcholine receptors of motor neurones in insects. This interaction results in convulsions, paralysis, and eventually death of the poisoned insect. It is effective on contact and via stomach action. Because imidacloprid binds much more strongly to insect neuron receptors than to mammal neuron receptors, this insecticide is selectively more toxic to insects than mammals. As a systemic pesticide, imidacloprid translocates or moves readily in the xylem of plants from the soil into the leaves, fruit, flowers, pollen, nectar, and guttation fluid of plants. Bees may be exposed to imidacloprid when they feed on the nectar, pollen, and guttation fluid of imidacloprid-treated plants. Experts believe that imidacloprid is one of many possible causes of bee decline and the recent bee malady termed colony collapse disorder (CCD). In 2011, according to the United States Department of Agriculture, no single factor alone is responsible for the malady, however honey bees are thought to possibly be affected by neonicotinoid chemicals existing as residues in the nectar and pollen which bees forage on. The scientists studying CCD have tested samples of pollen and have indicated findings of a broad range of substances, including insecticides, fungicides, and herbicides. They note that while the doses taken up by bees are not lethal, they are concerned about possible chronic problems caused by long-term exposure. In January 2013, the European Food Safety Authority stated that neonicotinoids pose an unacceptably high risk to bees, and that the industry-sponsored science upon which regulatory agencies' claims of safety have relied may be flawed, concluding that, "A high acute risk to honey bees was identified from exposure via dust drift for the seed treatment uses in maize, oilseed rape and cereals. A high acute risk was also identified from exposure via residues in nectar and/or pollen."An author of a Science study prompting the EESA review suggested that industry science pertaining to neonicotinoids may have been deliberately deceptive, and the UK Parliament has asked manufacturer Bayer Cropscience to explain discrepancies in evidence they have submitted to an investigation. April 2013 the EU decided to restrict thiamethoxam and clothianidin along with imidacloprid