Biopesticides are anything that kills a pest and is biological in origin as opposed to being synthesized in a laboratory. In the potato industry, the best known biopesticide is referred to as Bt, Bacillus thuringiensis. This is an example of a microbial biopesticide. B. thuringiensis is a soil bacterium, toxic to many insect larvae. There are several Bt-products registered on potatoes for foliar applications such as DiPel, Du-Ter and Javelin. Insect-killing genes of B. thuringiensis have also been introduced into the genome of several crops including potato, for example the New Leaf clones of several cultivars. As such, Bt has shown to be most effective.

There are also biochemical biopesticides. These are structurally related to natural substances and function identically to them. Their actions are non-toxic, so in a literal sense they are not pesticides. Examples are pheromones used to attract (trick) insects into thinking that they are with a mate thereby confusing their mating cycle or to attract them into traps.

Generally, all biopesticides exhibit the following characteristics:

• narrow target range
• highly specific mode of action
• suppress pests, not eliminate
• critical timing of application
• limited field persistence
• short residual effect
• safer to environment
• safer to people

Their use is best as part of an Integrated Management Program (IPM).