Integrated turf management - pest control using nematodes

Not only humans enjoy lawns and sports pitches. Crane flies (leatherjackets) and chafer grubs, relish them as well! A good reason why insect pathogenic nematodes effectively combat these major turf pests in a safe and natural way.

Nematodes for pest control, often referred to as entomopathogenic nematodes or beneficial nematodes, are microscopic roundworms that serve as natural agents for biological pest control. Beneficial nematodes are highly specific in their choice of hosts and do not harm beneficial insects, humans or animals. Common pests targeted by these nematodes include various larval insects like grubs and weevils (Coleoptera larvae), caterpillars (Lepidoptera), fly larvae (Diptera), Thrips (Thysanoptera) and many other soil-dwelling pests.

Benefits of nematodes

Using beneficial nematodes for pest control offers several key benefits. Nematodes are a perfect fit within Integrated Turf Management programmes due to their compatibility with most pesticides. They reduce the reliance on chemical pesticides and promote sustainable and eco-friendly pest management practices.  Nematodes are alive; they move through the soil profile and hunt their prey instinctively. And unlike chemical pesticides, which trigger an immune response in pests enabling them to adapt, nematodes remain highly effective over time.

Free of concerns about the diminishing performance of conventional pesticides and even pesticide resistance, we can rely on nematodes as a permanent solution for crop protection. In fact, currently only Aceleypryn is approved for use in amenity and sports turf settings against Leatherjackets and Chafer grubs. Unlike synthetic chemicals, nematodes do not leave any harmful residues, which makes them safe for the environment and those who handle them.

Beneficial nematodes use a fascinating strategy for parasitising and killing their host insects. Here’s how they work:

Entomopathogenic nematodes actively search or ambush potential insect hosts. They are attracted to their hosts by detecting clues emitted by the insects, such as carbon dioxide, heat and specific chemicals. Once the nematodes find a suitable host, the nematodes enter the host’s body through natural openings, such as the mouth, spiracles (insect breathing tubes), anus or soft cuticle areas. Some nematodes release enzymes to help digest and soften the host’s cuticle, allowing them to enter. Once inside the insect host, the nematodes release symbiotic bacteria, such as Xenorhabdus or Photorhabdus species, into the insect’s body cavity. These bacteria are essential for the nematode’s parasitic strategy.

The bacteria quickly multiply, causing septicemia (a lethal blood infection) in the host insect. The bacteria secret toxins and antimicrobial compounds that kill the host insect within a few days. The host becomes immobile and eventually dies due to the bacterial infection. The nematodes feed on the multiplying bacteria and absorb the nutrients released by the bacterial activity. This provides nourishment for the nematodes and supports their reproduction.

As the bacterial population within the host insect continues to grow, so do the nematode populations. The nematodes reproduce, developing through multiple juvenile stages into mature adults. Finally, after consuming the host insect’s tissues and the bacteria, thousands of new nematodes emerge from the dead insect’s body. These newly emerged nematodes are now ready to seek out new hosts and continue the cycle. The nematode population will slowly decrease once there are no new hosts present but will be active for up to two weeks if soil moisture levels are maintained.

What species of nematode to use

Steinernema carpocapsae is effective against a number of turf pests, especially the larvae of crane flies (leatherjackets). The crane fly goes through six stages of development: the egg stage, four larval stages and an adult stage. Adult crane flies only live for a few days. Some species have one generation per year, while others produce several generations in a year. This means that larvae can be found and can do damage year-round. Steinernema carpocapsae is an ambush forager, standing on its tail in an upright position (a process known as nictatation) near the soil surface and attaching to passing hosts. As an ambush forager, Steinernema carpocapsae is especially effective when applied against highly mobile surface-adapted insects, and below-ground insects are also controlled by this nematode. This species can sense carbon dioxide production, making the spiracles a key portal of entry into its insect hosts.

The insect pathogenic nematode Heterorhabditis bacteriophora can be used against chafer grubs in turf. These grubs immediately start feeding and are fully grown by autumn, causing extensive primary and secondary damage caused by birds and badgers.  As soil temperatures drop, grubs stop feeding and go deeper into the soil. During spring, they crawl closer to the surface, pupate and emerge as adults in May/June. Heterorhabditis bacteriophora nematodes boast a deep-moving active-hunting, with a cruising characteristic, which make them superior to many other species for grub control.

Nematode formulation

Nematode solutions are sustainably packaged and water soluble. The nematodes are kept dormant until they are ready for use, which extends their shelf life to several months. Recent developments have enabled Koppert to eliminate microplastics from its nematode products. Once mixed with and activated by water, nematodes can be applied by using standard spraying systems.

Enormous potential

The potential of beneficial nematodes to support the transition to integrated turf management is enormous. The opportunities for replacing conventional pesticides with natural, living alternatives will only continue to grow. With beneficial nematodes, turf managers can spray a solution that is full of life! free of residue and ready for a 100% sustainable future in the amenity and sports turf sector. Fundamentally, the use of nematodes in an integrated turf management programme will ensure that the amenity and sportsturf sector is addressing the key issues in land management as well as ensuring that this sector is managing turf in a sustainable manner and with the utmost level of consideration for the environment.

General guideline on how to apply nematodes

Good timing and application of nematodes is crucial. The application of beneficial nematodes is a straightforward process that ensures they come into contact with the target insects.

Nematodes can be applied by foliar or soil application, depending on the target pest.

• Choose the right nematode species tailored to your specific pest problem
• Determine the required nematode quantity based on the infestation severity and treatment area, and as indicated on the product labels
• Store nematodes in a refrigerated environment to maintain their effectiveness until the day of application
• Create a nematode suspension by mixing them with water following provided instructions
• In case of soil application: Ensure the soil is adequately moist (not waterlogged) to facilitate nematode movement. Also take the soil temperature into account
• In case of foliar application, the air relative humidity is another important factor to consider to maximise success (>75%)
• Ideally, apply nematodes during periods of moderate UV light, such as early morning or late afternoon, and avoid high sun intensity
• Spray nematodes evenly using various methods like sprayers, irrigation systems, drones etc. to help nematodes reach pest larvae
• Consider follow-up applications based on pest severity and nematode species
• Monitor and adjust your treatment plan as needed
• To ensure the best results, it is reccomended that nematodes are applied when the relative humidity is high (>75%); applied early morning or evening when solar radiation is low and when temperatures are ideally within 15°C – 25°C
• Nematodes can be mixed safely with water that is at pH values between 3-8 and EC values up to 5
• To ensure that nematodes can penetrate the turf surface an adjuvant such as Agrovista’s NemaFlow can also be used

Koppert have put endless efforts into research and development. The result is an innovative nematode spray solution, which acts as an effective alternative to its chemical counterparts today and addresses the push towards sustainable turf management in the future.

For more information visit www.koppert.co.uk