- General Information

Pheromones

What is it? Pheromones are chemical substances used in the animal world to transmit information from one individual to another. Mainly insects, first of all moths but also beetles like bark beetles, use this transmission to communicate. Amongst the different types of pheromones, like aggregation, alarm and tracing pheromones, the sex pheromones plays the most important role in the field of plant protection. They are released by female insects signaling their readiness for mating and allowing the males to track them down.

The pheromones, which are carried by the motion of air over great distances, are detected by the antennae of the males. These antennae are very sensitive instruments able to recognize single molecules. Pheromones are species specific attractants, each species has its own pheromone or pheromone blend.

What is it good for? Pheromones can be synthesized and used in pheromone traps as bait. The most important part of the trap is the so called dispenser which contains a small amount of the attractant. It mimics a female insect and thus lures the males into the trap. Pheromones are basically species specific and the males are attracted by the substances that are released by their own species only. This allows us to build traps for each pest individually.

Several types of use: There are several possibilities to take an advantage of pheromones.

  • The most common use of pheromone traps is for monitoring: A few traps are placed in the area of interest and by counting the number of insects caught in a certain period, information about the flight activity and the pest population density is easily available. Based on this information appropriate measures can be taken.
  • For several pests like bark beetles for example, the application of a larger amount of traps can be used as a means to reduce the number of insects and thus to reduce the damage they or their offspring (a female can deposit several hundreds of eggs) may cause. This method is called mass trapping.
  • An additional and in its effect different way of using pheromones as a plant protection method is the mating disruption or disorientation method. Many dispensers releasing a large amount of pheromone are placed all over the area that has to be protected. This generates a high and permanent concentration of pheromone which leaves the male insects blind. They are not able to locate the females who remain not impregnated and cannot reproduce themselves.

    • The advantages of the two latter methods are self explanatory. They help us to protect our plants against certain pests without the need of a pesticide and thus without polluting our environment. Due to the specificity of pheromones no other harmless or useful insects are killed.

    Advantage of monitoring: The advantage of monitoring is the easy availability of information about the flight activity of a particular pest. Simple observation of the traps in regular intervals is all that has to be done. No time consuming examination of the plants is necessary and no expert knowledge is needed. Appropriate proceeding is possible according to the outcome of the count. There are two main possibilities:

  • No catches of the target pest are observed: Provided that the traps are operated in the correct way and no insects are caught, it is most likely that no damage from this pest has to be expected. As a consequence no pesticide treatment is necessary. This saves work and money and keeps your plantation free of nature burdening pesticides.
  • Target insects are caught in the traps: This means some damage has to be considered. Fertilized females may lay eggs and hatched larvae

    • Trap types: 

  • Delta traps: .Changes in the population of the pest insects can be monitored by the use of TripheronTM traps. The transparent delta trap is optimized for this purpose, since an easy visual assessment is assured and the exchange of full sticky inserts is fast, clean and simple. The dispensers (carrier of the pheromone) have to be located in the center of the sticky insert.
  • Funnel traps: Monitoring of large insects or mass trapping
  • Panel or slot traps: .Mass trapping of bark beetles
  • Bucket or water traps: .Monitoring or mass trapping of several types of insects
  • and various others

    • Application: The pheromone trap should be ready for operation at the start of the flight activity of the pest insects. It is advisable to place the traps already one or two weeks before the expected flight period which is usually well known. Monitoring of stored product pests may be necessary throughout the whole year.

    Please control the traps regularly (usually every 3 days but at least once a week) and plot the results of the assessment into the table at the back side of this sheet. Indicate the date and the number of caught insects. It is advisable to remove the insects from the sticky insert or replace the insert after each assessment.

    Field application: For the monitoring of pest incidents usually one trap per hectare is sufficient. Place the trap approx. 50 m from the edge of the field and take care that traps are at least 100 m apart from each other. If you want to monitor different pest insects in the same plot, the traps for the different species should have a distance of at least 10 m.

     

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