Integrated Pest Management

A very beneficial aspect of integrated pest management is the use of control methods that are highly specific to the pest, whenever this is biologically or ecologically possible. This is important because it allows nontarget damages to be avoided or greatly reduced.

Often, the most useful pest-specific control methods involve the utilization of some sort of biological-control agents, such as a disease, predator, or herbivore that specifically attacks the pest species. The use of biological agents has been most successful in the case of invasive pests that have been introduced from another continent, and that are thriving in the absence of their natural control agents. The utility of biological control is best appreciated by considering some examples.

In the late nineteenth century the cottony-cushion scale insect (Icyera purchasi) was accidentally introduced from Australia to the United States, where it became a serious threat to the developing citrus industry of California. In one of the first triumphs of biological control, this pest was successfully managed by the introductions of an Australian lady beetle (Vedalia cardinalis) and parasitic fly (Cryptochetum iceryae).

Because it is toxic to cattle, the klamath weed (Hypericum perforatum) became a serious problem in pastures in southwestern North America after it was introduced from Europe. However, this weed was controlled by the introduction of two European beetles that eat its foliage. A similar success is the control of European ragwort (Senecio jacobea) in pastures in western North America through the introduction of three of its insect herbivores.

The common vampire bat (Desmodus rotundus) of subtropical parts of the Americas bites cattle and other animals in order to obtain a meal of blood, which may weaken the victims or cause them to develop diseases. This serious pest of livestock can now be controlled by capturing individual bats, treating them with petroleum jelly containing a pesticide, and then setting the animals free to return to their communal roosts in caves, where the poison is transferred to other bats during social grooming. This treatment is specific, and other bat species are not affected.

Another serious pest of cattle is the screw-worm fly (Callitroga ominivorax), whose larvae feed on open wounds and can prevent them from healing. This pest has been controlled in some areas by releasing large numbers of male flies that have been sterilized by exposure to gamma radiation. Because females of this species will only mate once, any copulation with a sterile male prevents them from reproducing. The sterile-male technique works by overwhelming wild populations with infertile males, resulting in few successful matings, and a decline of the pest to an economically acceptable abundance.