The most important part of the capsule system are the attractants. The identification of the right attractant substances and their mixture is done through electrophysiological and olfactometry methods.
The olfactometry methods help us to determine an applicable mixture that then will be classified in physical and chemical parameters.
Afterwards, a high quantity of attractants can be integrated into the outer shell and released over a long period of time. The liquid core inside is composed of an active substance and another substance which promotes feeding.
Usually attractants are divided in three categories according to their volatility (high, normal and low). Therefore, depending on the volatility, we use different methods to incorporate these mixtures in the outer shell of the capsule.
In nature the pest orientate itself through fragrance detected by its antennas. Thereby, we classified the attractants in two categories, near - and far orientation. Combinations of both classes can give the desired effect. Beside plant fragrance, sexual pheromones can be used to attract the pest. If required, we can add additional a toxin to kill the pest, when getting in contact with the capsule or when taking the nutrition out of the capsule. To finally complete the capsule system, we have to find the best concentration for all fragrances/compounds, to be more attractive than the plant, but not too high to be repellent.