Heterorhabditis bacteriophora, Beneficial Hb Nematode
Biocontrol Agent Factsheet
H. bacteriophora is a nematode (tiny worm) that attacks caterpillars and immature beetles (larvae), among other insects. It can also be used against white grubs in lawns. It actively searches out its prey in the soil, and does best in warmer soils (above 68 °F; 20 °C). This article focuses primarily on the use of Sf nematodes outside, and Sf strains that do not persist long-term after application.
Overview
Pests Targeted: Various beetles
Pest Stage: immature stages of pests (i.e., nymphs and larvae) are most susceptible
Commercially Available? Yes
Scientific Name: Heterorhabditis bacteriophora
Biocontrol Agent Type: Insect-killing nematodes
Common Names
Beneficial Hb Nematode
Relative effectiveness
Under the correct circumstances beneficial Hb nematodes can be extremely effective. Most pests included in the Pests Targeted table have been shown in field trials to be reduced by at least 70% when Hb nematodes are applied correctly.
Where to use
Use on a variety of ornamental or edible crops (including turf grass, berries, ornamental plants, vegetables, iris, citrus, cranberries), inside or outside. Apply directly to the soil around the root zone of the plant.
About Heterorhabditis bacteriophora
Beneficial nematodes, including Heterorhabditis bacteriophora (abbreviated here as Hb), live in the soil and are lethal parasites of many species of insects including important pests [8]. These nematodes are living organisms and thus require specific conditions and handling to be effective. The main considerations are matching nematodes with target pests, storage and application temperature, avoidance of exposure to ultraviolet light (sunlight), and avoidance of nematode application drying out too quickly [8]. Beneficial nematodes do not harm plants or animals [9].
- Native/Non-native: Native
- Preferred climate: humid, wet, temperate, Mediterranean, subtropical
- Region: So long as the nematode species being used is matched to the appropriate host and temperatures are within the effective range for use, nematodes can be used in a wide variety of regions. Soil conditions can influence beneficial nematode success. Nematodes may have a more difficult time establishing in heavy clay soils and may need more irrigation in sandy soils [10].
- Established: This article focuses on strains of Hb that do not establish long-term in the soil and require re-application.
- Where established: Beneficial nematodes occur throughout North America, but only certain strains are commercially available, and these generally do not persist or establish in the environment.
Heterorhabditis bacteriophora Appearance
Beneficial nematodes are very small and can be hard to see without a loupe/hand lens or microscope. Under magnification nematodes look like very small whitish to worms about 0.4-1.5mm in length [9]. Living Hb nematodes should be moving and have a bend [10]. If nematodes appear to be not moving and are perfectly straight, they are likely dead [10].
Beneficial nematode life cycle
Basic overview of beneficial nematode life cycle. Nematodes are applied as infective juveniles and seek out hosts in order to reproduce.
How to Use Heterorhabditis bacteriophora
Biocontrol category: Augmentative - must be released/applied repeatedly
When to use: To reduce the nematodes’ exposure to sunlight, beneficial nematodes should be applied in the early morning or evening. Typically Hb nematodes can be effective at soil temperatures above 68°F but be sure to follow directions provided by the supplier [10].
Rate: Follow instructions provided by the supplier. Research indicates a minimum of 25 nematodes per treated cm2, or 250,000 per meter2 (about 24,000 per square foot) should be used [11]. Use a sprayer nozzle with openings larger than 50 μm and an operating pressure less than 2000 kPa (290 psi) [12]. When nematodes are in suspension be sure to frequently (about every 5 minutes) agitate the container to keep the nematodes distributed equally in suspension and to supply them with oxygen [10].
Maximizing effectiveness: The most important considerations are to choose the beneficial nematode species most suited to control the target pest and conditions, and to ensure the correct application rate [8]. Ensure nematodes are living with a hand lens or microscope upon arrival and before use. Completely straight nematodes that do not move when prodded are likely dead. Taking a small droplet of the well mixed nematode solution, dilute if need be and evaluate if the mortality rate is over 20%. If you do find a mortality rate of over 20%, nematodes should not be used and the supplier should be contacted [10]. Store according to manufacturer specifications and be mindful of shelf-life. Sunlight (ultraviolet radiation) is extremely detrimental to nematode survival, thus try to apply in the early morning or evening to minimize exposure [13]. Beneficial nematodes are also sensitive to drying out, so timing application with rain or irrigation pre and post application will aid in maximizing effectiveness [14;15]. Typically it is recommended to maintain soil moisture for at least 2 weeks post application. Using Entomopathogenic Nematodes for Crop Insect Pest Control (pdf) is an excellent, extended, guide for using nematodes in crop settings from Washington State University Extension.
Pest stage: Immature stages of pests (i.e., nymphs and larvae) are most susceptible
Mode of action: Insect-killing nematodes (infects, kills and reproduces in insects)
Conservation: Although emerging evidence for the persistence of beneficial nematodes in some crop systems suggests some species can persist, nearly all commercially-available beneficial nematodes are not conserved effectively at levels suitable for sustained pest control among years [16;17]. This article focuses on Hb nematodes that need to be re-applied as needed. Unless you are purchasing nematodes from a persistent nematode supplier, assume they will not persist over multiple weeks/seasons.
Compatibility: Compatibility of Hb beneficial nematodes can vary with specific formulations and concentrations, and should be evaluated on a case by case basis. The Heterorhabditis Bacteriophora Compatibility Table is a summary of the existing information on compatibility of Hb nematodes with various pesticides and fertilizers.
Risk: Beneficial nematodes do not harm plants or animals. They have been shown to have little impact on nontarget arthropods [18].
Commercially available: Yes. Commercially available from a wide variety of suppliers. For more information see Commercial Availability of Insect-Killing Nematodes.
Any time you use a pesticide, you must read and follow the label directions and comply with all applicable laws and regulations related to pesticide use. Also be sure that any pesticide used is approved for use in your country and state/province.
Pests Targeted by Heterorhabditis bacteriophora
| Common Name (part of plant attacked) | Scientific Name | Crop(s) Targeted | Further Information |
|---|---|---|---|
| Bluegrass billbug (Root/stem) | Sphenophorus purvulus.*[1] | Turf | Managing Billbugs in Turfgrass - Purdue University Extension |
| Black vine weevil (Root/leafs) | Otiorhynchus sulcatus*[1] | Berries, ornamentals | Black Vine Weevil - Ohio State University Extension |
| Japanese beetle (Root/leafs) | Popillia japonica*[2] | Turf, ornamentals | Japanese beetles in yards and gardens - University of Minnesota |
| Masked chafer (Root) | Cyclocephala borealis*[2] | Turf | Masked Chafers - Ohio State University Extension |
| Iris borer (Root/ rhizome/leaf) | Macronoctua onusta*[3] | Iris | Iris borers - University of Minnesota Extension |
| Citrus root weevil (Root/leaf) | Diaprepes abbreviatus*[4] | Citrus | Diaprepes root weevil - - University of Florida |
| Cranberry rootworm (Root/leaf) | Rhabdopterus picipes*[5] | Cranberries | Cranberry Rootworm Beetle - Clemson University Extension |
| Carrot weevil (Root) | Listronotus oregonensis+[6] | Vegetables | Carrot Weevil - University of Massachusetts Extension |
| Western corn (Root, leaves, silk) rootworm | Diabrotica virgifera*[7] | Vegetables | Field Crops IPM - Purdue University Extension |
*Field efficacy of 70% or more per cited study
+Lab or greenhouse study with an efficacy of 70% or more per cited study
#Special application methodology
Note that this table may change over time.
Author
Michael Mueller
Cornell University Department of Entomology
Date: June 2022
- Special thanks to Amara Dunn, Kyle Wickings, and David Shapiro-Ilan for helpful feedback and suggestions during the writing of this article.
- Funding for completion of this article was provided by Cornell University’s Extension Outreach Assistantship.
[1] Smith, K.A. (1994) Control of weevils with entomopathogenic nematodes. In: Smith, K.A. and Hatsukade, M. (eds) Control of Insect Pests with Entomopathogenic Nematodes. Food and Fertilizer Technology Center, Republic of China in Taiwan, pp. 1–13
[2] Grewal, P. S., Power, K. T., Grewal, S. K., Suggars, A., & Haupricht, S. (2004). Enhanced consistency in biological control of white grubs (Coleoptera: Scarabaeidae) with new strains of entomopathogenic nematodes. Biological Control, 30(1), 73-82.
[3] Gill, S. A., & Raupp, M. J. (1997). Evaluation of biological and chemical applications for control of iris borer. Journal of Environmental Horticulture, 15(2), 108-110.
[4] Downing, A. S., Erickson, C. G., & Kraus, M. J. (1991). Field evaluation of entomopathogenic nematodes against citrus root weevils (Coleoptera: Curculionidae) in Florida citrus. The Florida entomologist, 74(4), 584-586.F
[5] Polavarapu, S., Stuart, R. J., & Schiffhauer, D. E. (2000). Evaluation of insecticides against cranberry rootworm, 1998. Arthropod Management Tests, 25(1).
[6] Miklasiewicz, T. J., Grewal, P. S., Hoy, C. W., & Malik, V. S. (2002). Evaluation of entomopathogenic nematodes for suppression of carrot weevil. BioControl, 47(5), 545-561.
[7] Toepfer, S., Knuth, P., Glas, M., & Kuhlmann, U. (2014). Successful application of entomopathogenic nematodes for the biological control of western corn rootworm larvae in Europe–a mini review. Julius-Kühn-Archiv, (444), 59.
[8] Shapiro-Ilan, D. I., Han, R., & Dolinksi, C. (2012). Entomopathogenic nematode production and application technology. Journal of nematology, 44(2), 206–217.
[9] Shapiro-Ilan, D.I., & R. Gaugler. (2010). Nematodes: Rhabditida: Steinernematidae & Heterorhabditidae. In: Shelton, A. (eds) Biological Control: A Guide to Natural Enemies in North America. Cornell University. Formerly available at: http://www.biocontrol.entomology.cornell.edu/pathogens/nematodes.html. And now available at: https://cals.cornell.edu/new-york-state-integrated-pest-management/eco-resilience/biocontrol/biocontrol-biology/insect-killing-nematodes
[10] Miles, C., Blethen, C., Gaugler, R., Shapiro-Ilan, D., & Murray, T. (2012). Using entomopathogenic nematodes for crop insect pest control. Pacific Northwest Extension Publication PNW544, 1-9. https://pubs.extension.wsu.edu/using-entomopathogenic-nematodes-for-crop-insect-pest-control
[11] Shapiro-Ilan, D. I., Gouge, D. H., Piggott, S. J., & Fife, J. P. (2006). Application technology and environmental considerations for use of entomopathogenic nematodes in biological control. Biological control, 38(1), 124-133.
[12] Georgis R., (1990). Formulation and application technology. In Gaugler, R. & Kaya, H.K. (Eds.). (1990). Entomopathogenic Nematodes in Biological Control. (pp. 173-194). CRC press.
[13] Gaugler, R., & Boush, G. M. (1978). Effects of ultraviolet radiation and sunlight on the entomogenous nematode, Neoaplectana carpocapsae. Journal of Invertebrate Pathology, 32(3), 291-296.
[14] Shetlar, D. J., Suleman, P. E., & Georgis, R. (1988). Irrigation and use of entomogenous nematodes, Neoaplectana spp. and Heterorhabditis heliothidis (Rhabditida: Steinernematidae and Heterorhabditidae), for control of Japanese beetle (Coleoptera: Scarabaeidae) grubs in turfgrass. Journal of Economic Entomology, 81(5), 1318-1322.
[15] Suggars Downing, A. (1994). Effect of irrigation and spray volume on efficacy of entomopathogenic nematodes (Rhabditida: Heterorhabditidae) against white grubs (Coleoptera: Scarabaeidae). Journal of Economic Entomology, 87(3), 643-646.
[16] Neumann, G., & Shields, E. J. (2011). Field persistence of Steinernema carpocapsae Weiser (NY001), Steinernema feltiae Filipjev (Valko) and Heterorhabditis bacteriophora Poinar (Oswego) in alfalfa fields. Gt. Lakes Entomol, 44, 42-52.
[17] Lauriault, L. M., Shields, E. J., Testa, A. M., & Porter, R. P. (2020). Persistence of select introduced entomopathogenic nematodes in the US Southwest as potential biological control for whitefringed beetle in alfalfa. Southwestern Entomologist, 45(1), 41-50.
[18] Georgis, R., Kaya, H. K., & Gaugler, R. (1991). Effect of steinernematid and heterorhahditid nematodes (Rhahditida: Steinernematidae and Heterorhahditidae) on nontarget arthropods. Environmental Entomology, 20(3), 815-822.
- Heterorhabditis bacteriophora nematodes viewed through a microscope (50x magnification).
- Basic overview of beneficial nematode life cycle. Nematodes are applied as infective juveniles and seek out hosts in order to reproduce. Diagram by Bill Joyner, USDA-ARS.
- Larva (immature) western corn rootworm. Photo credit: Scott Bauer, USDA Agricultural Research Service, Bugwood.org
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