Entomopathogenic Nematodes (EPN)

Technical articles

Principle

EPNs infect pests by entering their bodies through natural openings such as the mouth, spiracles, or anus. Once inside, they release symbiotic bacteria (Xenorhabdus or Photorhabdus), which multiply rapidly and produce toxins that kill the host within 24-48 hours. The nematodes feed on the host’s liquefied tissues, reproduce, and generate new infective juveniles (IJs) that emerge to seek new hosts, continuing the cycle. This efficient mechanism ensures rapid pest mortality while being safe for non-target organisms and the environment.

Benefits

Eco-Friendly Pest Control: EPNs offer a sustainable alternative to chemical pesticides.
Selective Targeting: They specifically target harmful pests without affecting beneficial insects.
Reduction in Chemical Use: Lower reliance on chemical inputs promotes healthier ecosystems.

Description

Depending on the pest and the area of application, different types of nematodes are used to achieve optimal results. For example, Heterorhabditis bacteriophora is suitable for black vine weevils in cooler climates, while Steinernema carpocapsae is effective against red palm weevils in high-temperature environments.
The nematodes specifically attack pests such as larvae and are harmless to humans and pets. This makes EPNs an optimal solution for pest problems across diverse agricultural systems.

Application

Mixing and Applying: Mix with water, apply using a sprayer or irrigation system. Apply early morning or evening when soil is moist and temperatures are cooler (refer to specific product website page for application guidelines and illustrations).
Frequency: Typically applied 2-3 times per year depending on pest pressure, crop type, and environmental conditions (refer to table and the remark).
Crop Categories: Root vegetables (e.g., potatoes, carrots), berries (e.g., strawberries, raspberries), leafy vegetables (e.g., cabbage), ornamentals, fruits and nuts trees, etc.
Pests: Effective against pests with significant soil interface exposure, such as white grubs, root weevils, and fungus gnats.
Winter Survival: EPNs can survive winter in soil under natural conditions, but populations decline significantly. Farmers may need to reapply annually for effective pest control.
Examples for timing for application (see product website page for more)-

Mole crickets: April to September.
Cutworms: June to August.
Meadow crane flies: September to mid-October (soil temperature at least 12°C)

1.Soil and Environmental Conditions:

Optimal temperature range: 5-35°C depending on the species.
Maintain high soil moisture (minimum 98% relative humidity) for effective nematode movement and pest invasion.
EPNs are sensitive to UV light; applications are best performed in the evening or under cloudy conditions.

2.Application Techniques:

Soil Drenching: Suitable for general field applications.
Dipping: Suitable for special cases like for strawberries.
Spraying: For turf and foliage applications, using appropriate nozzles to ensure EPN survival.
Drip Irrigation: Can be used with modifications to ensure even distribution.

3.Handling and Storage:

Store EPNs between 4°C and 10°C.
Avoid freezing or overheating; temperatures above 38°C are fatal to EPNs.
Ensure proper agitation of the solution during application to maintain oxygen levels.

Quality Control

Counting Live Nematodes: Ensure only live, active EPNs are used for application.
Infectivity Tests: Regular tests to confirm the efficacy of EPN batches.

Typical Species of EPN

Heterorhabditis bacteriophora: Known for its effectiveness against black vine weevil larvae in crops like strawberries and rhododendrons.
Steinernema feltiae: Commonly used for controlling sciarid flies in greenhouses and other soil-dwelling pests.
Steinernema carpocapsae: Targets red palm weevil and diamondback moth in cabbage.
Steinernema kraussei: Suitable for black vine weevil control in colder climates.

Examples of EPN Application

Heterorhabditis bacteriophora, Steinernema carpocapsae, and Steinernema feltiae are effective against all larval stages (L1 to L4) of Tuta absoluta(tomato leaf minor). EPNs can be applied via soil drenching or foliar spraying, targeting larvae in leaf tunnels and soil. Trials show over 60-85% larval mortality within 72 hours when EPNs are used during peak infestation periods. This eco-friendly approach reduces reliance on chemicals and provides rapid pest control for tomato crops.
Heterorhabditis bacteriophora is in controlling black vine weevil larvae in strawberry fields. This pest, which causes significant root damage, can be effectively managed by applying EPN during the larvae's active periods (April-May and August-September). Application can be through soil drenching or dipping the roots of plants before planting. Studies show a high efficacy rate, with mortality of vine weevil larvae reaching significant levels, providing a sustainable and effective pest management solution(product Nematop for e-nema).
General guiding table for farmers - Remark - The table provided showcases a few examples of EPN products, pests, and crops where these biological agents are effectively used. It is not a comprehensive list, as EPNs can be applied to many more pests and crops than mentioned here. Farmers can explore similar products for other nematode species, additional pests, and varied crops by referring to company websites like BASF, Koppert, and e-Nema, where detailed options are available. This broader market data enables farmers to make informed choices and calculate specific requirements for their fields.

Crop	Pest	EPN species	Commercial Product	Company	Dosage (per ha)	T°	Moisture	Applicatio ns per year	Cost (€/ha)
Potatoes, Turfs	White grubs	Heterorhabditis bacteriophora	Nemaseek	ARBICO Organics	2.5 billion nematodes	15-30°C	Moist soil (not waterlogged)	2 (sping & summer)	130-150
			HB Plus	e-Nema GmbH	2-3billion nematodes	18-28°C	Moist conditions	2-3 cycles	130-150
Carrots	Root weevils	Steinernema kraussei	NemAttack	ARBICO Organics	1 billion nematodes	14-32°C	High moisture	2 (early infestation period)	100-120
Strawberries	Black vine weevil	Steinernema feltiae	Kraussei	BASF	1-2 billion nematodes	10-30°C	Continuous moisture	2-3 during infestations	150-180
Tomatoes	Fungus gnats, Tuta absoluta	Steinernema feltiae	NemAttack	ARBICO Organics	1 billion nematodes	14-25°C	Consistent soil moisture	2-3 (during pest life cycle)	100
Cabbage	Cabbage maggot, Diamond black moth	Heterorhabditis bacteriophora	NemAttack	ARBICO Organics	1 billion nematodes	10-30°C	High soil moisture	1 (early spring)	100-120
Turf	Scarab larvae		GrubOut	e-Nema GmbH	2.5 billion nematodes	18-28°C	Moist soil	1 (spring)	60-80

Advantages and limits

1.Advantages:

For Farmers:

Reduce chemical pesticide use, lowering costs and residues on crops.
Enhance crop health and yields by effectively controlling soil-dwelling pests.
Provide long-term pest control when used as part of integrated pest management (IPM).

For the Environment:

Protect beneficial insects such as pollinators and predators, promoting ecological balance.
Reduce soil and water contamination caused by chemical pesticides.
Support biodiversity by targeting only specific pest species.
Improve overall soil health by maintaining natural soil organisms.

2.Limits:

For the Farmer: EPNs require precise application (timing and moisture) for optimal results, and the initial cost can be higher. While they can survive in soil for weeks to months, their population declines over time, necessitating annual reapplication to maintain pest control.
For the Environment: EPNs depend on high soil moisture for survival and effectiveness, making them less suitable for areas with frequent droughts unless irrigation is used.

Challenges and considerations

Sedimentation in Systems: Regular checks and agitation during drip irrigation to prevent uneven distribution.
Environmental Factors: Soil moisture and temperature are critical for EPN survival and efficacy.
Product Variability: Differences in nematode size and formulation affect product weight and application rates.
Equipment related: Always check for specific guidelines for spray nozzle dimensions and maintenance, etc.

The cost

The cost of EPNs varies depending on the product, species, dosage, and application method. Generally, it ranges from €90 to €160 per hectare for standard applications. These costs typically align with the information provided by manufacturers like BASF, Koppert, e-Nema and ARBICO Organics. Farmers are encouraged to visit these companies' websites to explore a wider range of products, calculate specific costs, and determine appropriate dosages and application criteria tailored to their needs.

Acknowledgment

We would like to extend our gratitude to Ghent University (IMaNema) and Professor Ralf Ehlers for their contributions to the understanding of EPNs and to e-Nema GmbH for their research and commercial products, which have advanced biological pest control practices. The data, techniques, and examples provided are drawn from their extensive work in this field. Special thanks to University Côte d’Azur (MSc BOOST) for providing us the platform for this work.

Product Websites

Available from agricultural suppliers like

BASF BioSolutions for Beneficial Nematodes(https://www.basf.com)
e-nema product page(https://www.e-nema.de)
Koppert Product Page(https://www.koppert.com)
ARBICO Organics(https://www.arbico-organics.com)
Grow it depot(https://www.growitdepot.com)
DSMZ (German Collection of Microorganisms and Cell Cultures)(https://www.dsmz.de)

Testimonials

In a video discussing the use of EPNs, farmers share their positive experiences. For example, one farmer reported significant reductions in pest populations and improved crop health after using Heterorhabditis bacteriophora to manage white grubs in their potato fields. They highlighted the ease of application and the noticeable difference in pest management compared to chemical methods. Biological Control: Entomopathogenic Nematodes (EPNs)

References

EPN studies from Ghent University, led by Professor Ralph Ehlers
Kumar, D., Kumari, P., Kamboj, R. et al. Entomopathogenic nematodes as potential and effective biocontrol agents against cutworms, Agrotis spp.: present and future scenario. Egypt J Biol Pest Control 32, 42 (2022). https://doi.org/10.1186/s41938-022-00543-5
Labaude, S.; Griffin, C.T. Transmission Success of Entomopathogenic Nematodes Used in Pest Control. Insects 2018, 9, 72. https://doi.org/10.3390/insects9020072
Patrick Fallet, Didace Bazagwira, Livio Ruzzante, Geraldine Ingabire, Sacha Levivier, Carlos Bustos-Segura, Joelle Kajuga, Stefan Toepfer, Ted C J Turlings, Entomopathogenic nematodes as an effective and sustainable alternative to control the fall armyworm in Africa, PNAS Nexus, Volume 3, Issue 4, April 2024, pgae122, https://doi.org/10.1093/pnasnexus/pgae122
Jacas Miret & Llácer Archelós, et al.Spraying EPN + Biorend before and after RPW infestation (2007)
Book Nematodes as biocontrol agents -by Parwinder S. Grewal, Ralf-Udo Ehlers and David I. Shapiro-Ilan August 2004, published by CABI.
OECD-COST Workshop Malente, Germany (1995) published in Biocontrol Science and Technology 6, 1996 (190 pp.)
Barbercheck + Millar (2000): Environmental impacts of EPN used for biological control in soil. In: Follett and Duan: Non-target Effects of Biological Control. Kluwer Academic Publ.
Akhurst + Smith (2002) Regulation + Safety of EPN. In. Gaugler: Entomopathogenic Nematology, CABI Bioscience

Annexes