Public concern over the level of pesticide use in food production has fostered the development of alternative, non-chemical methods of insect control. Microbial pesticides utilize insect pathogens as a means of reducing insect populations. Pathogens include various species of fungi, nematodes, and bacteria. The best known example of a microbial pest control product is the bacterium, Bacillus thuringiensis or Bt. Bt is commercially available and recommended for the control of a number of agricultural and forest pests.
Viruses comprise another important class of insect pathogens.
The potential for biological control by insect viruses, known as baculoviruses, has been studied for several years. The NPVs form large occlusion bodies of protein crystals which encase the virus particles. Occlusion bodies protect the virus from degradation in the open environment. Once ingested by the host insect, the occlusion bodies dissolve and the virus penetrates into the host tissue via the insect gut. The virus begins to replicate utilizing the genetic material of the host, eventually replacing much of the host's body material with new virus.