Insect resistance to a pesticide was first reported in 1947 for the Housefly (Musca domestica) with respect to DDT. Since then resistance to one or more pesticides has been reported in at least 225 species of insects and other arthropods. The genetic variants required for resistance to the most diverse kinds of pesticides were apparently present in every one of the populations exposed to these man-made compounds.
We can now determine, easily and relatively cheaply, the detailed chemical architecture of genes ; and we can trace the products of these genes ( enzymes and proteins ) as they influence the course of embryology . In so doing we have made the astounding discovery that all complex animal phyla - arthropods and vertebrates in particular - have retained, despite their half-billion years of evolutionary independence, an extensive set of common genetic blueprints for building bodies.