This is ten years old, but summarizes the difference between nicotine and neonicotinoids, and the apparent safety of the newer products. I am sure some will be skeptical of this, but it is definitely not a propaganda piece
> Neonicotinoids, the most important new class of synthetic insecticides of the past three decades, are used to control sucking insects both on plants and on companion animals. Imidacloprid (the principal example), nitenpyram, acetamiprid, thiacloprid, thiamethoxam, and others act as agonists at the insect nicotinic acetylcholine receptor (nAChR). The botanical insecticide nicotine acts at the same target without the neonicotinoid level of effectiveness or safety.
>
> Fundamental differences between the nAChRs of insects and mammals confer remarkable selectivity for the neonicotinoids. Whereas ionized nicotine binds at an anionic subsite in the mammalian nAChR, the negatively tipped neonicotinoids interact with a proposed unique subsite consisting of cationic amino acid residue(s) in the insect nAChR. Knowledge reviewed here of the functional architecture and molecular aspects of the insect and mammalian nAChRs and their neonicotinoid-binding site lays the foundation for continued development and use of this new class of safe and effective insecticides.
>
> The long-term future of neonicotinoids will depend on continued evidence for the human and environmental safety of current compounds, including low toxicity to predators, parasites, and pollinators, no adverse environmental distribution, and fate. It will be enhanced by the discovery of new compounds with a broader spectrum of useful properties including control of lepidopterous larvae and pest strains resistant to earlier analogs.
>
> These biological features must be combined with suitable hydrophilicity for transport in plants, hydrophobicity for contact activity, and photostability for residual efficacy. Much has been learned about neonicotinoids in the first decade of their use and about the nicotinic receptor as a target for selective toxicity between insects and mammals. The benefits of neonicotinoids in crop protection and animal health can be enjoyed for many decades ahead with attention to their proper use in pest management systems that delay or circumvent the development of resistance in pest insects.
ACKNOWLEDGMENTS
Neonicotinoid research in the Berkeley laboratory was supported in part by grant R01 ES08424 from the National Institute of Environmental Health Sciences, the National Institutes of Health. The authors received valuable advice and assistance from our former or current colleagues S. Kagabu, N. Zhang, and G.B. Quistad.
Motohiro Tomizawa and John E. Casida
Environmental Chemistry and Toxicology Laboratory, Department of Environmental
Science, Policy and Management, University of California, Berkeley, California
Annu. Rev. Entomol. 2003. 48:339–64
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