Predators of pests

Biological and Natural Controls. Parasites and predators are effective in limiting the numbers of pest Insects and plant pathogens both in nature and for crops (35). This basic fact led to the development of biological controls. For example, the vedalia beetle, which was Introduced for control of cottony cushion scale on citrus in California, has provided continuous effective control of this pest for many decades. Worldwide only approximately 1% of the pests have been effectively controlled by Introduced biological control agents (43). 

Some capsids are useful predators of small pests, particularly on fruit. 

Several species of mites (order Acarina) are effectively controlled by oil sprays. The European red mite, a major pest of fruit in the northeastern United Stat, is a member of this group. This pest appears to have become more severe as a result of the general use of DDT. Such a situation is explained by the fact that mites are not controlled by DDT, while certain parasites and predators of mites are killed by it. The continued use of DDT under these circumstances favors the build-up of mites. 

Ladybugs are natural predators of aphids, mealy bugs, and leaf hoppers and may be introduced into a garden environment as a nonchemical pest-control method. 

Organic systems seek to have a more measured pace of crop growth which encourages a more robust plant to resist pests and diseases. The greater balance of biodiversity achieves a more natural level of pest predators and a non-stressed crop is more likely to resist disease. Unless specifically targeted, some pesticides will kill beneficial as well as pest insects. 

Organic growers also use biological control. They are allowed to import natural enemies of pests. This works either through predation or parasitism. This has proven effective for the control of red spider mite and specific caterpillars, and does not affect other insects. And a third technique is to use insect traps ranging from sticky yellow strips to pheromone or sexual lures. The pheromone traps use synthetic extracts of the chemical scents that... 

On a small scale, there is possibly no less expensive way of protecting stored agricultural produce like grain against predation by pests than using a thin coating of vegetable oil. It must be... 

Using low doses of insecticides—In doing so, plenty of susceptible phenotypes will be spared. The use of reduced application rates is also in line with current IPM programs. In the past, most spray schedules and label directions for insecticide use were found to be overprescribed because of the philosophy of pest eradication (Metcalf, 1980). It is now believed that an insecticide which kills 50% of the insect pest and none of its predators is more valuable than one which kills 95% of insect pests but at the same time eliminates their natural enemies. 

Predators and Parasites—Organisms known to attack insert (and insect-like) pests in their native environment can be imported or reared in labomto-ries and released in infested areas. This is done only after the parasites or predators are determined to be harmless to man, animals, plants, and other beneficial organisms. For example, several kinds of parasites and predators of the alfalfa weevil have been imported from Europe and Asia and released in the infested areas in this country. Several species have become established and are helping to reduce pest numbers. However, they do not always prevent serious outbreaks and the resultant damage. 

Millipedes are slow-moving, deliberate animals which usually live in damp and dark places, often under some sort of cover. Some species of millipedes feed on living plants, and when these animals are abundant they can cause significant damage. For example, Oxidus gracilus, a common millipede found in greenhouses, is sometimes considered to be a pest. A few species of millipedes are predators of other invertebrates. 

The pest insects that eat our treasured ornamentals and rob a share of the vegetable harvest are only a tiny fraction of the total insect population around us. The overwhelming majority of insects are harmless members of the natural community. Many are directly beneficial in their role as crop pollinators, predators on pests, and decomposers of plant material, d hey can be as common as houseflies, distributed globally, or as rare as the flea that lives on the skin of certain sea mammals or the midge that lives in the tiny pool of water in a pitcher plant. 

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