Benzoylurea insecticide

Benzoylureas (BPUs) are chemical derivatives of N-benzoyl-N′-phenylurea, which are used as insecticides.^[1] They do not directly kill the insect, but disrupt moulting and egg hatch, and thus act as insect growth regulators. They act by inhibiting chitin synthase,^[2] preventing the formation of chitin in the insect's body.

Chemical structure of diflubenzuron, a commonly used benzoylurea insecticide

The insecticidal activity of the BPUs was discovered serendipitiously at Phillips-Duphar who commercialised diflubenzuron in 1975.^[1] Since then, many BPUs were commercialised by many companies. BPUs accounted for 3% of the $ 18.4 billion world insecticide market in 2018.^[3] Lufenuron, was the largest selling BPU in 2016, selling for $ 112 million.^[4]

BPUs are active against many types of insect pests, (e.g. lepidoptera coleoptera, diptera) in agriculture,^[1][5] as well as being used against termites and animal health pests such as fleas.^[6]

The Insecticide Resistance Action Committee (IRAC) lists the following BPUs, which are classified in IRAC group 15:^[7] bistrifluron, chlorfluazuron, diflubenzuron, flucycloxuron, flufenoxuron, hexaflumuron, lufenuron, novaluron, noviflumuron, teflubenzuron, and triflumuron. Many older BPUs are no longer in use.^[1][5]

Mammalian and environmental toxicity

BPUs have a good mammalian tox profile. Diflubenzuron is considered to be of very low acute toxicity, and is approved by the WHO for treatment of drinking water as a mosquito larvicide.^[8]

BPUs  have low acute toxicity against bees, low to moderate toxicity to fish, but high toxicity to aquatic invertebrates and crustaceans.^[1]

BPUs have various rates of degradation in the environment. Some older BPUs have high persistence and are no longer sold.^[1] Flufenoxuron was shown to bioaccumulate and was banned in the EU in 2011.^[9]