According to the Biopesticide, Pollution, Prevention Division (BPPD) at the US Environmental Protection Agency (EPA), which registers biological pesticides for sale, biological pesticides or biopesticides are certain types of pesticides derived from such natural materials as animals, plants, bacteria and certain minerals. Biopesticides fall into three major classes: microbial pesticides, plant-incorporated-protectants (PIPs) or biochemical pesticides.

• Microbial pesticides consist of a microorganism (e.g. a bacterium, fungus, virus or protozoan) as the active ingredient. The most widely used microbial pesticides are subspecies and strains of Bacillus thuringiensis (Bt).

• Plant-incorporated-protectants (PIPs) are pesticidal substances that plants produce from genetic material that has been added to the plant. For example, scientists can take the gene for the Bt pesticidal protein, and introduce the gene into the plant's own genetic material. Then the plant, instead of the Bt bacterium, manufactures the substance that kills the pest.

• Biochemical pesticides are naturally occurring substances that control pests by non-toxic mechanisms. Conventional pesticides, by contrast, are generally synthetic materials that directly kill or inactivate the pest. Biochemical pesticides include substances such as insect sex pheromones that interfere with mating, as well as various scented plant extracts that attract insect pests to traps (Environmental Protection Agency, 2007).

This chapter will focus only on microbial and biochemical pesticides because microbial and biochemical pesticides continue to have challenges with adoption on a large scale, whereas PIPs are widely adopted on millions of hectares in US agriculture.