Imidacloprid (a neonicotinoid) molecule. Computer artwork showing the molecular structure of imidacloprid. Imidacloprid is a neonicotinoid, a class of neuro-active insecticides chemically similar to nicotine. Imidacloprid is the most widely used insecticide in the world. Neonicotinoids have been linked to adverse ecological effects, including honey-bee colony collapse disorder, and loss of birds, due to a reduction in insect populations. Atoms are represented as spheres: carbon (light-blue), chlorine (green), hydrogen (white), nitrogen (dark-blue), oxygen (red), and bonds between the atoms by cylinders.