Beneficial nematodes, including entomopathogenic nematodes (EPN), are micropscopic unsegmented roundworms that parasitise and control specific plant pests. These naturally occurring organisms work in symbiosis with bacteria to target and eliminate hosts. Through this specific mode of action, they are safe to use as they will naturally die off when no pests are present anymore.des will leave the dead host and move on to penetrate new hosts.
Working mechanism beneficial nematodes
- Host detection
Nematodes locate pests by detecting chemical signals in the soil or on plant surfaces - Host penetration
Once they found a host, they enter through the natural openings, such as:
• Mouth
• Anus
• Spiracles (respiratory openings) -
Infecting the host through symbiotic bacteria
After penetration, nematode release symbiotic bacteria (Photorhabdus or Xenorhabdus species) inside the pest. These bacteria multiply rapidly and deteriorate the host from within. The nematodes feed on the released nutrients and continue their cycle, while the host becomes immobile and dies. -
Reproduction and new cycle
The nematodes start with the next juvenile stadia to complete the cycle. A new generation of nematodes will leave the dead host and move on to penetrate new hosts.
Challenges to overcome
Beneficial nematodes need the right environmental conditions to thrive during soil or foliar applications. Specifically for soil applications, it is important to wet the ground before and after the application, while relative humidity is a key parameter for foliar applications. In both cases, it is advised to apply nematodes early in the morning or late afternoon to avoid direct sunlight that dries them out.
The efficacy of the nematode species also depends on the right temperature range for maximum efficacy:
- Steinernema feltiae: 10 – 30°C
- Steinernema carpocapsae: 12-30°C
- Heterorhabditis bacteriophora: 12-30°C
- Steinernema kraussei: 5-30°C
- Phasmarhabditis californica: 5-30°C
They 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.
Correct timing and appropriate release, considering dose rates, repetitions and place of introduction, of beneficials are crucial to success.
Benefits
Beneficial nematodes are eco-friendly and not harmful to the environment, animals or humans. They are also very easy to use through standard spraying devices.
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.
Beneficial nematodes are helping to manage resistance build in the diminishing range of available chemical crop protection products. They are also compatible with other beneficials and most (bio)pesticides.
When to use beneficial nematodes
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.
EPNs are used to eliminate pest larvae and pupae in the soil before they emerge as adults, breaking the pest lifecycle before infestation occurs. By targeting the most vulnerable life stages, maximum efficacy can be ensured.
If pest pressure suddenly increases, they can be used curatively in higher concentrations to quickly suppress the population.
Want to know more about beneficial nematodes?
Curious about how beneficial nematodes can support your pest management strategy? Or do you have specific questions about their application? Feel free to reach out to our experts. They’ll be happy to provide you with more information and tailored advice.