A relatively small number of known insects are considered pests of humans and their environment. In fact, the majority of insects perform functions that allow them to be beneficial to humans. They break down organic matter, pollinate plants, and even attack insects known to be pests. The latter example makes these insects truly "beneficial" because they serve as natural enemies of pest species in the environment. A natural enemy can be a predator, a parasitoid, or a competitor.

Predators

Predators are insects and other non-insect arthropods that consume several to many prey items over the course of their development. Predators are free living (i.e., mobile), and usually bigger than their prey. Some arthropods are predaceous only as immatures (larvae, nymphs), while others are predaceous both as adults and immatures. Predator species may feed on a wide variety of prey species, making them generalist predators, or they may be very selective and feed on a specific prey, making them specialist predators. Lacewings, mantids and numerous species of flies, beetles, spiders, and mites are a just a few examples of some beneficial arthropods.

Parasitoids

Parasitoids are beneficial arthropods that, during their development, live in or on the bodies of their host organisms, eventually killing them. (A parasite is different in that it usually does not kill its host.) Parasitoids usually deposit one or many eggs into or on the body of their host or in their hosts' habitat. The larvae from these eggs then will feed on the tissues and body fluids of the host. This process slowly consumes the host. During the early stages of parasitoid development, the host stays alive, but later in the development the host species dies, and the parasitoid, depending on the species, pupates either inside or outside of the host body. Finally, the adult parasitoid emerges from within the body of the host, or from a cocoon located nearby. Most parasitoids are small to minute in size, and are usually one of numerous species of wasps, certain flies, and some beetles.

Pathogens

Pathogens are microorganisms such as nematodes, bacteria, viruses, fungi and protozoa. Pathogens used as biological control agents cause a disease that weakens or kills the host and usually are host specific.

Herbivores

Herbivores are host specific weed biological agents that feed and reproduce on invasive plants. The damage caused by herbivores weakens or kills the host plant. Examples of weed biological control agents include arthropods (insects and mites), plant pathogens (fungi, bacteria, viruses, and nematodes), and fish (grass carp).

Competitors

Competitors are organisms that compete with others for the same resources. Certain genera of dung beetles and non-pest flies have been used for this type of pest management, but the use of competitors for pest management is not very common.

Biological Control

Living natural enemies (predators and parasitoids, pathogens and herbivores) can be used to control pests. This process is referred to as biological control. During biological control, natural enemies are released and manipulated by humans in order to eliminate or keep pest species under control.

There are three basic methods of biological control: classical biological control, conservation, and augmentation.

Classical Biological Control

Classical biological control involves importing and establishing the natural enemy of a pest species into a new area. This type of control is very important to pest management because many pest species found in an area often were imported from other countries through immigration and trade. In their native habitat, these pest species cause little damage because they have natural enemies that aid in keeping their populations under control. However, once these pests arrive into a new environment, the natural enemies that once kept them in check often are not present.

In order to successfully apply this type of control, the pest's native habitat must be explored, and one or more species of its natural enemies must be collected. The natural enemies are then quarantined and tested to ensure that they themselves will not become pests. Once this is determined, the natural enemies are then reared in laboratories and released in areas were the pest is located until one or more species becomes established. If the establishment of one or more introduced beneficial organisms is successful, the result is a reduction in or suppression of the pest population, often on a permanent basis.

Conservation

Conservation of natural enemies is important because it can increase the impact of natural biological control on pest populations. Conserving natural enemies helps to regulate pest densities. Listed below are several practices that help to conserve and increase natural enemy populations.

• Recognizing beneficial insects enables us to tell which insects are "good" and which are "bad," and then determining whether control is necessary.

• Minimizing pesticide applications benefits natural enemies as they are usually more susceptible to pesticides than their prey, so only treating plants when the damage is severe will reduce the losses in natural enemy populations.

• Using selective pesticides so as to target only specific organisms, while avoiding harm to beneficial arthropod populations. This allows growers to maintain their natural enemy levels and, as an additional benefit, decrease the amount of sprays needed each year on their crops.

• Maintaining ground cover, standing crops, and residues as they are often major sources for harboring natural enemies. Ground cover gives natural enemies a place to reside, while standing crops and residues offer an alternative food source (nectar, pollen, other prey species) for the natural enemies once the pest population gets too low. This in turn keeps the natural enemies from leaving that area.

• Providing additional pollen and nectar sources or other supplemental foods for beneficial organisms.

These practices may or may not affect the number of pest organisms in a particular area. The ultimate goal of conservation is to limit the damage that pests do by manipulating key elements in the environment to increase the number of natural enemies.

Augmentation

Augmentation involves the release of natural enemies into areas where they exist at levels too low to provide effective biocontrol. The insects or non-insect arthropods (usually mites) used in this type of control are usually obtained from commercial insect rearing facilities and shipped in their inactive stage (egg, chilled adult, or pupae). These stages are then placed into the habitat where the pest is located. Augmentation is most often used in conjunction with conservation in order to maximize the benefits of both types of biological control.

Augmentation is divided into two categories: seasonal inoculative releases and inundative releases.

• Seasonal inoculative releases involve introducing natural enemies into an area in which they can survive indefinitely due to favorable conditions. Once their population increases in number, they will begin to suppress the pest population for an extended period of time (usually less than one year). One or two inoculative releases are generally made in a single season.
• Inundative releases usually involve a large number of natural enemies intended to quickly overwhelm and reduce the pest population. These releases may or may not result in a season-long establishment of the natural enemies in that particular area. This type of release is ideal for pests that undergo only one to two generations per year.

The purpose of this CD-ROM, which is the first in a series, is to familiarize county Cooperative Extension Service faculty, Master Gardeners, Master Naturalists, the media, growers and other interested individuals and organizations with information about selected predatory beneficial insects, spiders, and mites found in Florida and often present elsewhere.

The CD-ROM provides basic information on the description, location, life cycle (in some cases), and habitat of these arthropods, as well high quality images of these organisms for use in fact sheets and bulletins; non-commercial Web sites; trade industry magazines, newspapers and other media; and audience presentations, subject to the restrictions described on the main page.