Tree Fruit Research & Extension Center

Orchard Pest Management

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Mating Disruption PDF format

-- Jay F. Brunner and Alan Knight

Mating disruption involves the use of sex pheromones to prevent male insects finding females and mating. Pheromones are chemicals produced by an insect to communicate in some way with others of the same species.



There are several types of pheromones. For example, ants lay a trail pheromone to direct other ants to a food source. Aphids release an alarm pheromone that warns other aphids of potential danger, usually the presence of a predator or parasite. Sex pheromones are chemicals released by female insects to attract males from long distances to mate. A female releasing a pheromone is said to be ''calling'' the male. The male flies upwind, crisscrossing the pheromone plume, following the increasing concentration until it finds the source. After mating, the female stops calling.



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Pheromones of many different insects have been identified and synthesized. When a small amount of a species' pheromone is put into a rubber or plastic dispenser and placed in a trap, males of that species are attracted to the trap as they would be to a calling female. These pheromone traps are used to monitor the activity or even estimate the density of some Lepidoptera that are pests of fruit crops.



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The pheromone of most moths has from 2 to 6 components. Different components or different ratios of the same components make them specific attractants for a species. For example, several leafroller species have pheromones with the same components. Specificity results from components being present in different ratios in different species.

Other insects, such as campylomma, scales and mealybug, also produce pheromones and may be candidates for mating disruption. After mating, the female stops calling.



Pheromones of many different insects have been identified and synthesized. When a small amount of a species' pheromone is put into a rubber or plastic dispenser and placed in a trap, males of that species are attracted to the trap as they would be to a calling female. These pheromone traps are used to monitor the activity or even estimate the density of some Lepidoptera that are pests of fruit crops.



The pheromone of most moths has from 2 to 6 components. Different components or different ratios of the same components make them specific attractants for a species. For example, several leafroller species have pheromones with the same components. Specificity results from components being present in different ratios in different species.

Other insects, such as campylomma, scales and mealybug, also produce pheromones and may be candidates for mating disruption.

 
How mating disruption works

There are several ways mating disruption may work. Dispensers in the orchard might mimic a calling female, attracting the male to many false sources, or dispensers might release so much pheromone that the background concentration masks normal communication.



It is important to understand how mating disruption works because different mechanisms can influence how pheromones should be used in the orchard. Four different mechanisms have been proposed to explain how mating disruption works. It is possible that for a pest species more than one of these mechanisms could be operating at the same time to achieve control. The mechanisms are:

 
Pheromone dispensers

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The dispensers used to release a pheromone in mating disruption are just as important as using the right chemicals. If the right pheromone is used, but is released too slowly, then the concentration in the atmosphere might be too low to block mate finding. If, on the other hand, the dispenser releases pheromone too fast, control might not last as long as needed.



Several types of dispensers have been used in mating disruption tests. Pheromones have been impregnated in rubber tubing, incorporated in plastic wafers, placed inside hollow fibers and even formulated into sprays.



The most common dispenser systems used in mating disruption on fruit crops incorporate pheromones in plastic tubes, ampules or packets designed to release the product slowly over several weeks. The dispensers are usually placed in the orchard by hand, at a rate of 150 to 400 per acre. Different dispenser systems containing the same pheromone may not provide the same level of pest control. It will take careful research on each type of dispenser system to find out how well they disrupt mating.

 
Benefits of mating disruption

 
Factors influencing mating disruption

 
Mating disruption in the Pacific Northwest

Several characteristics of fruit production in the Northwest make mating disruption appealing and may contribute to its success.

 
Regulation and registration

The U.S. Environmental Protection Agency (EPA) regulates only certain uses of pheromones. The use of pheromones in traps to monitor insects is not regulated. However, if the intent is to prevent, destroy, repel or otherwise mitigate a pest population, the EPA considers pheromone a pesticide and regulates its use through registration.

The EPA has recognized that pheromones are inherently different from conventional pesticides and supports the concept of mating disruption as an environmentally safe pest control tactic. Pheromones have a unique, nontoxic mode of action, are highly specific, occur naturally, and are used in very low volumes.

The EPA has developed a tiered testing scheme to ensure that the minimum amount of data is needed to register them. Pheromones do not need to undergo further testing if they pass all the first tier data requirements. The EPA has waived the requirement for a tolerance on food crops, as the chances of residues are nil. The EPA has registered pheromone products to control oriental fruit moth, peachtree borer and codling moth, as well as pests on some nonfood crops. It has taken much less time to register these products than to register conventional pesticides.

 
Mating disruption successes

One of the most successful examples of mating disruption has been on oriental fruit moth. Control of oriental fruit moth with a pheromone has been reported to be as good as or better than with conventional insecticidal control in several orchards in California. The pheromone was registered in 1986 and in 1990 was used on 10,000 acres of peach orchards in Washington and California.

A pheromone product to control codling moth was registered in 1991. Research has produced mixed results, although under the right conditions the product has given good control.

 
Gallery

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The book, Orchard Pest Management, is copyrighted by the Washington State Fruit Commission. Permission is granted by the Commission to Washington State University to publish the book's content on the World Wide Web. Soft cover copies are available for purchase.

 

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