Side effects of pesticides on Amblyseius swirskii

When introducing a new natural enemy, knowledge about the additional effects of natural enemies is initially very limited. It is important to build up this knowledge quickly and carefully. This takes places in various ways: through dedicated (laboratory) research, observations in field trials and the evaluation of experiences in practice. Naturally, for the grower, the side effects in practice are the most important thing to know about. These effects are described by means of an estimate of the effect that occurs when the natural enemy comes into contact with the agent concerned.

A category classification has been agreed within the IOBC (International Organisation for Biological and Integrated Control) regarding mortality (and/or the reduction in capacity, i.e. the effect on the control capacity) as a consequence of the use of chemical agents (see table 1).

Table 1: Categories



reduction in control capacity


< 25%

Slightly harmful

25 - 50%

Moderately harmful

50 - 75%

Very harmful

> 75%

Alongside this effect, the persistance is also of importance: an estimate of the length of time that the agent still impacts on the natural enemy after application. For natural enemies, this period is generally expressed in weeks after the most recent application of the agent.

It is important to see the information on side effects as a guideline and not as an absolute value that is identical in every situation. The season, the crop, the growth, the climate, the dosage used and the application technique all play a role in the end effect.
Furthermore, a chemical application just after the introduction of natural enemies generally has more of a negative effect than when used on an established population of natural enemies. If no alternative food (such as pollen) is available, the application of agents that destroy the predatory mites’ prey will lead to the considerable reduction of the population of predatory mites.


New data from research and practice becomes available on a regular basis. The current information on the side effects of chemical agents on A. swirskii can be found at

If in doubt about any of the information, it is advisable to contact your crop advisor or a Koppert Consultant before applying the product in question. Only use chemicals registered for application. Always read the label before use.

For more information read our Explanation of the Side effects