Having several species of pollen- and nectar-producing plants in an area will provide resources more continuously than only having one species. For example, many adult predators and parasitoids feed on nectar and pollen, so it is essential to have these resources nearby. Farmscaping is a term sometimes used to describe the creation of habitat to enhance the chances for survival and reproduction of beneficial organisms. Natural enemies are common and a grower can design production systems to attract and keep the natural enemies in the system by providing environmental conditions conducive to the enemies' survival. In many cases, purchasing natural enemies to provide biological control agents is not necessary. Approaches to Biological Controlīiological control can be natural: conservation of natural enemies or applied: inoculation or inundation. Uninfected Beet armyworm (bottom), and beet armyworm killed by a nuclear polyhedrosis virus (NPV). As with all biological control agents, it is especially important to match the correct microbial control agent with the correct pest in order for them to be effective.įigure 4. The insect-parasitic (entomopathogenic or insecticidal) nematodes, Steinernema and Heterorhabditis, infect soil-dwelling insects and occur naturally or can be purchased. Nuclear polyhedrosis viruses (NPV) and granulosis viruses (GV) viruses are available to control some caterpillar pests. These are most often used against foliar insect pests in greenhouses or other locations where humidity is relatively high. Several insect-pathogenic fungi are used as microbial control agents, including Beauveria, Metarhizium, and Paecilomyces. Because not all formulations of Bt are approved for use in organic systems, it is important to check with your certifier before using this. One very well-known microbial control agent that is available commercially is the bacterium Bacillus thuringiensis (Bt). Biological control using pathogens is often called microbial control. The main groups of insect disease-causing organisms are insect-parasitic bacteria, fungi, protozoa, viruses, and nematodes. Just as many other organisms get sick, so do insects. Photo credit: Merle Shepard, Clemson University,. Parasitoids often require a source of food in addition to their host insect, such as nectar or pollen.įigure 3. The eggs hatch, enter the host, and kill it. They look like large houseflies and deposit their white, oval eggs on the backs of caterpillars and other pests. Tachinid flies are another group of parasitoids. Many parasitoids are very small wasps and are not easily noticed. When the eggs hatch, the immature parasitoids use the host as food. Adult parasitoids lay their eggs in, on, or near their host insect. Parasitoids (sometimes called parasites) do not usually eat their hosts directly. Some common predatory arthropods include ladybird beetles, carabid (ground) beetles, staphylinid (rove) beetles, syrphid (hover) flies, lacewings, minute pirate bugs, nabid bugs, big-eyed bugs, and spiders.įigure 2: Preying mantid consuming insect prey. Natural enemies of arthropods fall into three major categories: predators, parasitoids, and pathogens (Altieri et al., 2005 Mahr et al., 2008). Barbercheck, Penn State University Introductionīiological control is the use of living organisms to maintain pest populations below damaging levels.
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