Beneficial insects, mites and nematodes

Beneficial insects, mites and nematodes are naturally occurring macro-organisms harnessed to control specific plant pests. They are commonly called ‘natural enemies’, biocontrol agents or macrobials.

  • Beneficial insects are a group that includes parasitoids and predatory bugs. Parasitoids lay eggs on, or inside, pests – resulting in host death, while predatory bugs feed directly on one, or more, pests. These insects can exhibit generalistic behaviour, feeding on several different species or pests, others are specialists.
  • Beneficial mites are tiny predatory mites that directly feed on several plant pests.
  • Beneficial nematodes, also called entomopathogenic nematodes, are a group of soil-dwelling microscopic worms that parasitise and control specific insect pests.

Challenges to overcome

Beneficial insects, mites and nematodes need pests to complete their development. As in nature, this acts as a stabilising mechanism which means the biocontrol agent needs the appropriate pest, or feed supplement, to establish in the crop.

For a long-term control strategy, the beneficials needs to keep the pest population in check, ie below the economic damage threshold but not eliminate it from the crop.

Correct timing and appropriate release, considering dose rates, repetitions and place of introduction, of beneficials are crucial to success.


Macrobials are eco-friendly and are not harmful to the environment, animals or humans.

By creating a self-sustaining system, with a low level of pest and an established population of beneficials, chemicals are only used as a last resort – minimising/eliminating chemical residues.

Biocontrols are helping to manage resistance build in the diminishing range of available chemical crop protection products.

When to use macrobials

Used preventively, growers install a ‘standing army’ of natural enemies in the crop. Ready to take on a newly emerging pest threat, this reduces the risk of the pest reaching problematic (crop damaging) densities. These macrobial standing armies can be maintained with re-introductions or by introducing a supplementary food source to build up the beneficial populations.

If pest pressure suddenly increases, macrobials can be used curatively. These IPM strategies generally centre on higher macrobial introduction rates.

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