Secondary plant metabolites can be small lipophilic molecules (SLMs) with similar physicochemical properties and toxicities to pesticides
and many have provided the lead structure or inspiration for synthetic
insecticides for example, pyrethrum for the pyrethroids nicotine and other nicotinic acetyl-choline receptor agonists for the neonicotinoids and stemofoline for the very recently introduced butenolides.
Some insecticides are natural products, for example spinosad, which comprises the natural spinosyns A and D.
Thus genes for the biosynthesis of the natural insecticidal SLMs are available in nature for exploitation by genetic engineering