Sulfoxaflor is a systemic insecticide which acts as an insect neurotoxin and is a member a class of chemicals called sulfoximines which act on the central nervous system of insects.
Sulfoxaflor is classified for use against sap-feeding insects as a sulfoximine, which is a sub-group of insecticides that act as nicotinic acetylcholine receptor (nAChR) competitive modulators. Sulfoxaflor binds to nAChRs in place of acetylcholine. Sulfoxaflor binding causes uncontrolled nerve impulses resulting in muscle tremors followed by paralysis and death.
Other nAChR competitive modulator sub-groups that bind differently on the receptor than sulfoximines include neonicotinoids, nicotine, and butenolides.
Because sulfoxaflor binds much more strongly to insect neuron receptors than to mammal neuron receptors, this insecticide is selectively more toxic to insects than mammals.
Application is only recommended when pollinators are not likely to be present in an area as sulfoxaflor is highly toxic to bees if they come into contact with spray droplets shortly after application; toxicity is reduced after the spray has dried.
On May 6, 2013, the United States Environmental Protection Agency (EPA) approved the first two commercial pesticide products that contain sulfoxaflor, marketed under the brand names "Transform" and "Closer", to the Dow Chemical Corporation. This pesticide has been registered in South Korea, Panama, Vietnam, Indonesia and Guatemala.
On September 10, 2015 the U.S. 9th Circuit Court of Appeals overturned the EPA's approval of sulfoxaflor, citing insufficient evidence from studies regarding bee health to justify how sulfoxaflor was approved. Beekeepers and environmental groups supported the decision, saying that the EPA must assess the health of entire hives, not just individual bees.