What’s a nematode, anyway? Beneficial insects are a type of microscopic roundworm that lives in the soil and uses insect pests as its food throughout its lifespan. Although roundworms may seem dangerous, the kind that is used for pest control is actually beneficial and cannot harm you in the same way that some worm species that infect people and animals can. Additionally, roundworms will not damage your soil or plants. There is no danger in coming into contact with them.
Beneficial nematodes are rightfully deemed beneficial because they target pests that we don’t want to encounter, including insect larvae, caterpillars, and white grubs. Nematode applications can be effective in reducing pests if the soil conditions are ideal (moist, not too cold or too hot, etc.). You should apply the nematodes twice, with a two-week interval between applications, in order to ensure that the population will be diverse enough to continue breeding and prospering while feeding on pests in the soil.
Nematodes are typically applied to the soil surface because they thrive in dark, moist conditions, which can be found at or below the soil surface. Some species of insect are able to survive being sprayed on plant leaves. You can use different species of predators to target different pests in different areas of your garden.
Life Cycle Of Beneficial Nematodes
The life cycle of a nematode is not something that can be seen with the naked eye, but it is still interesting to know about. Nematodes go through three stages just like other bugs: egg, larva, and adult. The larvae of this species go through four distinct stages. The third stage is when they find an insect host and lay claim to it. Many species of parasites enter the bodies of their hosts by way of the mouth, while others are able to penetrate the exoskeleton and enter through an opening in it.
The nematode larvae enter their target pests and spread bacteria from their guts inside the host insects. The bacteria breaks down the insect pests’ tissues. The larva of the nematode then eats the tissues that are infected with bacteria, and as a result, the host insects die. Nematodes can kill their hosts very rapidly and lay eggs while livinginside the host and still feeding. Depending on the host, a nematode may be able to create one or more generations while living inside an insect!
Types Of Beneficial Nematodes
There are many different types of nematodes, but only a small number are used for controlling pests in gardens. Nematodes come in many different varieties, some of which are parasitic and dangerous to humans and pets. Others, like root-knot nematodes, consume plant matter. Fortunately, the beneficial nematodes will also help control the harmful nematodes!
Some of the different varieties of nematode good guys include those that prey on host bugs.
Steinernema Feltiae (Sf)
The Nematode Steinernema feltiae, typically indicated by the abbreviation Sf on product labels, is most commonly used for parasite control in outdoor and greenhouse settings. This product is effective against fungus gnat larvae, a common pest for houseplants, making it a good option for indoor plants. The most common beneficial nematode is the Steinernema feltiae, which can be easily found in local gardening centers. One of the most common methods of controlling nematodes is through this species.
SF can also handle a variety of other pests, including beet armyworms, black cutworms, cabbage maggots, codling moths, corn earworms, crane flies, cucumber beetle, fruit flies, onion maggots, raspberry crown borers, root maggots, sclarids, shore flies, subterranean termites, sweet potato weevils, thrips, ticks, and tobacco cutworm. It can also kill nematodes that are harmful to plants, like root-knot nematodes, or other pests that live in the soil.
Heterorhabditis Bacteriophora (Hb)
Heterorhabditis bacteriophora, or Hb, is a common nematode product that should be easy to find. This grass is often grown in outdoor locations such as lawns, gardens, pastures, fields, and orchards. You will want to have this kind on hand to help eliminate or control ants and Japanese beetles if you have problems with them.
In addition to queen ants and Japanese beetles, these will also attack insect larvae of the asparagus beetle, banana moths, banana weevils, berry root weevils, billbugs, black vine weevils, carrot weevils, European and masked chafers, citrus root weevils, Colorado potato beetle, corn rootworms, cranberry root weevils, spotted cucumber beetle, flea beetle, leafminers, May/June bugs, root weevils, scarabs, sugarcane stalk borers, sweet potato weevils, and ticks. They will also treat borers that attack a variety of other plants, including iris, tree, and vine varieties.
Steinernema Carpocapsae (Sc)
Sc is the third most commonly found type of nematode that is beneficial to crops. This is a flea control product, typically used on pets that spend a lot of time outdoors. You can use this product on lawns, landscapes, fields, and orchards, and it can also be used on indoor plants.
This pesticide can kill a variety of bugs, including but not limited to: armyworms, artichoke plume moths, beet armyworms, black cutworms, black vine weevils, bluegrass weevils, caterpillars, corn earworms, cotton bollworms, cranberry girdlers, cucumber beetle, cutworms, fall armyworms, flea larvae, fly larvae, fruit flies, greater peach tree borers, lesser peach tree borers, large pine weevils, leafminers, mint flea beetles, mint root borers, mole crickets, navel orange worms, strawberry root weevils, tobacco budworms, webworms, wireworms, and wood borers. They can also eliminate American, Asian, and German cockroaches.
Steinernema Kraussei (Sk)
Skis are typically used in places that have cooler weather, so it may be hard to find them in certain parts of the US. This pesticide is effective against most weevil species, including the black vine weevil, sawfly weevil, and filbert worm. It is often used in outdoor or greenhouse settings. If you live in an area that is prone to weevil infestations, these predators are incredibly effective at keeping the population under control and are definitely worth having around.
Steinernema Riobrave (Sr)
Sr is a less common beneficial nematode, but it can still be useful if you are able to purchase it. This pesticide is effective against pests that are attracted to citrus plants, as well as some pests that live in lawns.
Nematodes of this species can kill the following pests: armyworms, black cutworms, black vine weevils, blue-green weevils, chafers, citrus root weevils, citrus weevils, corn earworms, Diaprepes root weevils, greater wax moths, green June beetle, hive beetle, Indian meal moths, Japanese beetle grubs, masked chafers, May/June beetle, mole crickets, pink bollworms, plum curculios, red flour beetle, strawberry weevils, and subterranean termites.
Choosing the Right Nematode for Your Climate
You need to consider the temperature of your soil during the growing season while also choosing the right species to control the particular pest you are dealing with.
Some people prefer hot weather while others work better in lower temperatures.
During hot weather, those in the genus Heterorhabditis are especially active. H. indica can survive in high temperatures and can attach to insects when the soil temperature is 86°F or hotter.
H. bacteriophora is not as effective at lower temperatures, thriving best in warmer environments.
The different species of Steinernema prefer different temperatures. The S. riobrave is a creature that can be found in a variety of temperature ranges, from 59 to 95°F.
This species of plant was originally found in the Rio Grande Valley in Texas. It is able to survive in semi-arid conditions.
S. feltiae is different from other commonly used insecticidal nematodes because it can survive at temperatures as low as 50°F.
2 In contrast, S. carpocapsae is the most effective when the soil temperature is between 72 and 82°F.
One reality of selecting nematodes for pest control is that their action is not immediate, but it is still effective over time. After applying the insecticide, the first batch of host insects will die within 24 to 48 hours.
We need to be realistic about the behavior and timeline of these beneficial creatures. The “they” in this text refers to a parasitic generation that has infiltrated its hosts. The hosts are feeding and reproducing the parasites, who will then be ready for their own generation.
They will continue hunting and staying active unless they run out of food or the temperature gets too extreme for them. Organic management practices require close attention to detail and regular scouting.
Don’t be afraid to get your hands dirty.
Take some time to look for grubs and larvae that are infected in your garden. Note what you see. You should check on your beneficial nematodes 48 to 72 hours after you’ve applied them, and then again a week or two later.
This approach is focused on the garden as a whole, and will take some time to see results. In addition to monitoring the plants’ growth, pay attention to the soil temperature and how it changes over time. This will give you a better idea of how the plants are doing and whether they’re getting the right amount of sunlight and nutrients.
Application and Use
You may be wondering how to use these useful organisms in your garden! Mulches can be used in different ways around your home. You can use them in your vegetable garden, for your ornamental beds, in containers, on your lawn, or in your pasture.
Insecticidal nematodes are sometimes applied to plants above the ground – to eradicate leafminers in plant tissue, for example – not just to soilborne insects.
What pests do you want to kill? Consider the behaviour of each species we have discussed.
For example, does your target pest live near the surface or deeper down? The temperature of the soil is important to determine because it can affect the growth and development of the target pest. Is the soil compact or sandy?
The number of nematodes you will need to purchase is affected by the size of the area you are treating. If you wanted to treat 1,600 square feet of land, you would need to buy 5 million of them. If you wanted to treat an acre, you would need 50 million of them.
If you’re growing plants in containers or a greenhouse, you’ll need to use more fertilizer.
Nematodes are very sensitive to UV light, so you should apply them in the morning or evening to avoid them being exposed to direct sunlight.
Applying in the evening is particularly important to avoid heat damage. Soil temperatures will be lower at dusk.
How Do They Look When They Arrive?
Nematodes are typically received in one of four forms: gel, clay, dry granules, or water-filled sponges All of these forms will dissolve in water. Just follow the package directions.
If you want your products to be certified organic, you should be aware that nematodes shipped in granules or clay may not be certified.
Don’t worry if you get a bag of dead insects! Nematodes that are beneficial to gardens are often sold while they are still inside their insect hosts. Wax mealworms are often used as a source of commercially available insecticidal nematodes.
Use this method if you want the juveniles to appear in a specific location. Scatter them on the ground in that location, and they will emerge.
Apply when the time is right. Do your homework to ensure you are using beneficial nematodes to target the right pests. These nematodes will help to keep the population of targeted pests in check while also providing a food source.
The best time to apply [pesticides] is in the spring or fall when most of the [targeted] insects are in their larval stage. The larvae are the most vulnerable stage as they are still in the soil.
If you are unsure about the life cycle of the pest you are trying to remove, you can always contact your local extension agency for more information on the specific pest.
Compatibility with Garden Chemicals
Insecticidal nematodes that kill juvenile insects are surprisingly compatible with many types of garden chemicals. This means they can be sprayed together with most fungicides and herbicides.
Fertilizers only become a problem when you use fresh manure or high concentrations of chemical fertilizers like urea.
Many insects can survive being sprayed with organophosphates like diazinon, and carbaryl (Sevin) is only moderately poisonous to them.
If you’re unsure if your chosen chemical insecticide is compatible with insecticidal nematodes, you can wait 1-2 weeks to apply them.
The labels on the packages of chemicals will usually have the information you need to know about which chemicals will be safe to use with your chosen species.
Irrigation: Keep the Soil Moist
Pay attention to the moisture content of your soil. Make sure you wet the ground really well before you put anything on it.
Be sure to water the area around plants to rinse off any nematodes and send them down into the soil closer to their targets.
If you are treating turf for a white grub problem, it is especially important to do this. The thick thatch can make it difficult for the nematodes to get into the soil.
Watering the lawn after applying grub control will help the chemicals travel through the thatch and reach the grubs in the soil.
After applying the product, you will want to keep the soil moist for a few weeks to ensure that the product remains active and effective in killing the insects. If there is no rain, you should water every three to four days.
How to Physically Apply
If you have a larger area to treat, you can use a garden hose with a small nozzle To apply the nematodes, you can use a watering can if you are targeting a small area. If you have a larger area to treat, you can use a garden hose with a small nozzle. There are a few different ways to water larger areas – using a pump sprayer, end-hose sprayer, irrigation system, backpack sprayer, or motorized sprayer.
The simplest method for applying pesticides is to use a hose-end sprayer to meter the amount being applied.
Mix the beneficiary nematodes with water and make sure to shake them so they are evenly dispersed when you spray them. If the nematodes are not mixed well, they will settle.
Note: using a hydraulic pump with high internal and shear forces can be dangerous. They can shred your nematodes!
You can expect to see results within two weeks.