on natural, biological processes. Supplemental inputs will undoubtedly be required, however, to achieve EBPM. These will include biological-control organisms and products, narrow-spectrum synthetic pesticides, and resistant plants.

Biological-Control Organisms

Biological-control organisms are living organisms that can be used to manage arthropod (mites and insects), weed, and plant (bacteria, fungi, viruses, and nematodes) pests and pathogens. Generally, control organisms do not immediately alleviate disease or prevent or curtail attack; they also do not immediately reduce the pest population. Rather, control is generally achieved over a period of several generations. Biological control organisms commonly interacting with their hosts at low population densities, preventing pests from reproducing to economically important population levels. Control organisms are themselves arthropods, plants, and pathogens and are as diverse as the pests (Ferris, 1992; Flint, 1992; Schroth et al., 1992; Turner, 1992):

  • arthropods that prey on or parasitize other arthropods,

  • arthropods that prey on or parasitize plants,

  • pathogens of plant pests,

  • bacterial or fungal antagonists of plant pathogens,

  • beneficial nematodes that parasitize arthropods,

  • mild strains of plant pathogens, and

  • other beneficial organisms that parasitize or prey on plant pathogens or nematodes.

Predatory arthropods can be very host specific, depending on their ability to locate, consume, and utilize a particular prey species for growth and reproduction; however, environmental factors and habitat may modify prey specificity. A predator invariably consumes more than one individual during its life span and, if conditions are favorable, some arthropod organisms kill hundreds of host individuals during their development. Arthropod parasitoids attack and disarm the arthropod host species and subsequently deposit one or more eggs within or on the host organism. Parasitoid larvae then feed on and complete development on a host individual, and in the process, kill the host. Parasitic organisms are usually highly host and habitat specific. Arthropod herbivores that prefer feeding on weed plants can be used as controls, feeding on foliage, roots, stems, flowers, fruit, or seeds of weeds.

Viruses, bacteria, fungi, protozoa, and other microbes that cause disease in arthropods, plant pathogens, or weeds are also used as biological-control organisms. Under favorable conditions, they infect their hosts and can cause epidemics that can lead to a marked decline in the pest population. Certain of these persist on the plant, in the pest, or in the environment, causing recurring infections in their hosts.

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