Field Crop Beneficials

Beneficial Organisms Insects and other organisms are often categorized as being harmful or beneficial. Harmful organisms are often defined as those that damage crops, sting, bite or spread diseases and beneficial organisms include those that pollinate crops, produce useful products or kill harmful organisms. Thus the terms are often very subjective and often may depend on the eye of the beholder. For example honey bees are usually though of as beneficial because they pollinate crops and produce honey which are useful activities, however if a swarm takes up residence in your home and you get stung then your are more likely to define them as harmful. Even plant feeding organisms may be considered beneficial if they are feeding on unwanted plants where as they may be harmful if they begin feeding on desirable plants.

Biological Control AgentsOne way that organisms are said to be beneficial is when they help control pest populations. The action of one living organism controlling the populations of another organism is called biological control and the organisms that feed on pests are called natural enemies. Virtually all insect and mite pests have some natural enemies. Learning to recognize and manage these natural enemies can help reduce pests populations and, thus, reduce crop losses and the need for costly chemical and/or other control measures.

Parasitoids Parasitoids are insects that, in the immature stages of their life cycle, parasitize other insects but have free­living (nonparasitic) adults. Adult parasitoids serve mainly to transport their offspring to new hosts. Two major groups of parasitoids are parasitic wasps and tachinid flies. Pathogens A pathogen is a parasitic organism that causes disease in its host. Typically, pathogens are much smaller than their hosts, and usually numerous pathogens infect a single host. Two categories of pathogens that are common as biological controls of insects are nematodes, which are multicellular; and various microbial pathogens, which consist of single cells or subcellular units.

Predators Predatory insects and mites live by hunting or trapping other insects (prey), and killing them for food. Over 100 families of insects, spiders and mites contain species that are predaceous, either as adults, immatures or both. Some of the more common groups of predators include, lady bird beetles, syrphid flies, lacewings, predaceous stink bugs, nabids, orius, ground beetles and spiders. Weed Control Agents A weed is sometimes described as a plant out of place. Some of our most notorious weeds are plants that have been introduced into new environments and then proceed to displace other plants. One method that has been used to combat some of these introduced weeds is to introduce insects that feed on these weeds.

Related Publications

Pub Number: MF2222 (Pdf )

Description: Well-researched applications of natural enemies can result in effective biological control. This includes use of microbial insecticides & many specific uses of predators & parasitic insects.

Authors: Michaud, J. P. -- Sloderbeck, Phillip E. -- Nechols, James R.

Publication Date: March 2008