How often do I need to use biological control nematodes?
Contrary to what you may hear, in most cases biological control nematodes do not persist for a long time after they are applied. Most of these nematodes can live for only a few weeks at most without their host insect. Biological control nematodes occur naturally in most environments. They kill a few insects and help reduce insect epidemics. If they killed off all of their host insects, the nematodes would die off too. When we apply commercially available biological control nematodes, we are attempting to overload the natural system and kill many more insects than would be killed by nematodes naturally. If the treatment is successful, and most of the pest insects die, the nematode populations decline as well. Soon the natural balance is restored. When insect populations begin to build back up another nematode application is required.
The use of insect parasitic nematodes and other biological control agents to manage insect pests has grown in popularity. This is primarily due to the changing problems associated with pest control. For example, many pests have developed resistance to certain pesticides, new pests have arisen to replace those successfully controlled, the effectiveness of natural control agents (predators, parasites and pathogens) has been reduced by pesticide use, pesticides are no longer inexpensive to use, and there is increased concern about pesticide safety and environmental quality. These beneficial organisms can be an important component of an integrated pest management (IPM) program for ornamental crops and turf grass sites.
Before and after applying beneficial nematodes
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What are beneficial nematodes?
Nematodes are morphologically, genetically and ecologically diverse organisms occupying more varied habitats than any other animal group except arthropods. These naturally occurring organisms are microscopic, unsegmented round worms that live in the soil and, depending on the species, infect plants and animals. The two nematode families Steinernemae and Heterorhabditidae, contain the insect parasitic nematode species. The most commonly used beneficial nematodes are Steinernema carpocapsae, S. feltiae, and Heterorhabditis bacteriophora. Nematodes that are endoparasites of insects attack a wide variety of agricultural pests.
The life cycle of beneficial nematodes consists of eggs, four larval stages and the adults. The third larval stage is the infective form of the nematode (IT). They search out susceptible hosts, primarily insect larvae, by detecting excretory products, carbon dioxide and temperature changes. Juvenile nematodes enter the insect host through the mouth, anus or breathing holes (spiracles). Heterorhabditid nematodes can also pierce through the insect’s body wall. The juvenile form of the nematode carries Xenorhabdus sp. bacteria in their pharynx and intestine. Once the bacteria are introduced into the insect host, death of the host usually occurs in 24 to 48 hours.
As the bacteria enzymatically breaks down the internal structure of the insect, the Steinernemae develop into adult males and females which mate within the insect's body cavity. Heterorhabditids produce young through hermaphroditic females. This form of nematode has the sexual organs of both sexes. As the nematodes grow, they feed on the insect tissue that has been broken down by the bacteria. Once their development has reached the third juvenile stage, the nematodes exit the remains of the insect body.
Why are these organisms beneficial? Parasitic nematodes are beneficial for six reasons. First, they have such a wide host range that they can be used successfully on numerous insect pests. The nematodes' nonspecific development, which does not rely on specific host nutrients, allows them to infect a large number of insect species.
Second, nematodes kill their insect hosts within 48 hours. As mentioned earlier, this is due to enzymes produced by the Xenorhabdus bacteria. Third, nematodes can be grown on artificial media. This allows for commercial production which makes them a more available product.
Fourth, the infective stage is durable. The nematodes can stay viable up to 3 weeks when stored at the proper temperature. Refrigerated at 37o to 50o F. They can also tolerate being mixed with herbicides and fertilizers. Check nematode product label for compatibility. Also, the infective juveniles can live for some time without nourishment as they search for a host.
Fifth, there is no evidence of natural or acquired resistance to the Xenorhabdus bacteria. Though there is no insect immunity to the bacteria, some insects, particularly beneficial insects, are possibly less parasitized because nematodes are less likely to encounter Beneficial's which are often very active and escape nematode penetration by quickly moving away.
Finally, there is no evidence that parasitic nematodes or their symbiotic bacteria can develop in vertebrates. This makes nematode use for insect pest control safe and environmentally friendly. The United States Environmental Protection Agency (EPA) has ruled that nematodes are exempt from registration because they occur naturally and require no genetic modification by man.
How do you know which nematodes are
beneficial and which ones are garden pests themselves?
Scientists have spent years studying and identifying the life cycle
of different types of nematodes. While there are nematodes that
parasitize garden plants, the species being sold as beneficial
nematodes have been thoroughly studied and their life-cycles are
well understood. We can even buy specific species of beneficial
nematodes for a special need. The most effective nematode for our
garden problems is a combination of two species, Steinernema
and Heterorhabditis.
Can nematodes hurt me or anything else? Studies
have shown that these beneficial nematodes only target very specific
pests and neither the nematode nor the toxins they produce can harm
vertebrates. That leaves out all of us as well as our pets, birds,
squirrels, etc. They don't hurt earthworms either.
What types of pest problems will beneficial nematodes help
control? The specific type of nematode you buy for garden
use targets any garden pest that has a larval stage in the soil. In
our area, that would be cutworms, grubworms, many borers, root
weevils, cabbage maggots, sod webworms and others. Many garden pests
such as rose chafers have a larval stage in the soil, so they would
be affected too.
What about iris borers? There has been some
exciting work done on using beneficial nematodes to control iris
borers. In a study done at the University of Maryland, beneficial
nematodes applied by their guidelines did as good a job as any other
treatment, including the now banned Cygon. For gardeners who want to
avoid using harsh chemicals such as Cygon, beneficial nematodes may
be a great alternative.
Steinernemae & Heterorhabditis
Nematodes are simple roundworms. Colorless, unsegmented, and lacking appendages, nematodes may be free-living, predaceous, or parasitic. Species are beneficial in attacking insect pests, mostly sterilizing or otherwise debilitating their hosts. A very few cause insect death but these species tend to be difficult (e.g., tetradomatids) or expensive (e.g. mermithids) to mass produce, have narrow host specificity against pests of minor economic importance, possess modest virulence (e.g., sphaeruliids) or are otherwise poorly suited to exploit for pest control purposes. The only insect-parasitic nematodes possessing an optimal balance of biological control attributes are entomopathogenic or insecticidal nematodes in the genera Steinernema and Heterorhabditis. These multi-cellular metazoans occupy a biocontrol middle ground between microbial pathogens and predators/parasitoids, and are invariably lumped with pathogens, presumably because of their symbiotic relationship with bacteria.
Entomopathogenic nematodes are extraordinarily lethal to many
important insect pests, yet are safe for plants and animals. This
high degree of safety means that unlike chemicals, or even
Bacillus thuringiensis, nematode applications do not require
masks or other safety equipment; and re-entry time, residues,
groundwater contamination, chemical trespass, and pollinators are
not issues. Most biologicals require days or weeks to kill, yet
nematodes, working with their symbiotic bacteria, can kill insects
within 24-48 hours. Dozens of different insect pests are susceptible
to infection, yet no adverse effects have been shown against
beneficial insects in field studies (Georgis et al., 1991; Akhurst
and Smith, 2002). Nematodes are amenable to mass production and do
not require specialized application equipment as they are compatible
with standard equipment, including various sprayers , backpack,
pressurized, mist, electrostatic, fan, and aerial) and irrigation
systems.
Hundreds of researchers representing more than forty countries are
working to develop nematodes as biological insecticides. Nematodes
have been marketed on every continent except Antarctica for control
of insect pests in high-value horticulture, agriculture, and home
and garden niche markets.
Life Cycle
Steinernemae and heterorhabditids have similar life histories. The non-feeding, developmentally arrested infective juvenile seeks out insect hosts and initiates infections. When a host has been located, the nematodes penetrate into the insect body cavity, usually via natural body openings (mouth, anus, spiracles) or areas of thin cuticle. Once in the body cavity, a symbiotic bacterium (Xenorhabdus for steinernemae, Photorhabdus for heterorhabditids) is released from the nematode gut, which multiplies rapidly and causes rapid insect death. The nematodes feed upon the bacteria and liquefying host, and mature into adults. Steinernemae infective juveniles may become males or females, whereas heterorhabditids develop into self-fertilizing hermaphrodites although subsequent generations within a host produce males and females as well.
The life cycle is completed in a few days, and hundreds of thousands of new infective juveniles emerge in search of fresh hosts. Thus, entomopathogenic nematodes are a nematode-bacterium complex. The nematode may appear as little more than a biological syringe for its bacterial partner, yet the relationship between these organisms is one of classic mutualism. Nematode growth and reproduction depend upon conditions established in the host cadaver by the bacterium. The bacterium further contributes anti-immune proteins to assist the nematode in overcoming host defenses, and anti-microbials that suppress colonization of the cadaver by competing secondary invaders. Conversely, the bacterium lacks invasive powers and is dependent upon the nematode to locate and penetrate suitable hosts.
Beneficial Nematodes -For Pest Insects
Beneficial nematodes seek out and kill all stages of harmful soil-dwelling insects. They can be used to control a broad range of soil-inhabiting insects and above-ground insects in their soil-inhabiting stage of life. More than 200 species of insect pests are susceptible to these insect predators.
They are a natural and effective alternative to chemical pesticides, and have no detrimental effect on non-target species such as ladybugs, earth worms and other helpful garden insects. Finally, there is no evidence that parasitic nematodes or their symbiotic bacteria can develop in vertebrates. This makes nematode use for insect pest control safe and environmentally friendly.
Beneficial nematodes can be applied anytime during the year when
soil-dwelling insects are present .
10 Million nematodes, Garden Size: will treat up to 3,200 sq.ft
50 Million nematodes will treat up to 1/2 acre.
100 million nematodes will treat up to an acre.
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Steinernema feltiae |
Steinernema carpocapsae |
Heterorhabditis bacteriophora |
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Target Pests: Fly pests fungus gnats), Plant parasitic nematodes, Humpbacked flies, Fruit flies, Raspberry crown borer, Leaf miners, Cabbage maggot, Cucumber beetles, Shore flies, Black cutworm, Tobacco cutworm, White grubs, Beet armyworm, Onion maggot, Subterranean Termite. |
Target Pests: Fleas, Codling moth, German cockroach, Asian cockroach, American cockroach, Fruit fly, Armyworm, Beet armyworm, Cucumber beetle, Artichoke plume moth, Cutworms, Sod webworm, Black cutworm, Mole cricket, Corn earworm, Cotton bollworm, Tobacco budworm, Leaf miners, Iris Borers. |
Target Pests: Weevils, Beetle grubs, Japanese beetle, Masked chaffers, May/June beetles, Black vine weevil, various white grubs, Banana weevil, Bill bug, Colorado Potato beetle, Cucumber beetle, Sweet potato weevil, Asparagus beetle, Carrot weevil, Banana moth, Citrus root weevil group, Sugarcane stalk borer, Various tree and vine borers, Bagworms, Flea beetle, Flea. |
Beneficial nematodes infest grubs and other pest insects that are known to destroy lawns and plants.
The Nematodes are effective against grubs and the larval or grub stage of Japanese Beetles, Northern Masked Chafer, European Chafer, Rose Chafer, Fly larvae, Oriental Beetles, June Beetles, Flea beetles, Bill-bugs, Cut-worms, Army worms, Black Vine Weevils, Strawberry Root Weevils, Fungus Gnats, Sciarid larvae, Sod Web-worms, Girdler, Citrus Weevils, Maggots and other Dip-tera, Mole Crickets, Iris Borer, Root Maggot, Cabbage Root Maggot and Carrot Weevils.
Beneficial nematodes belong to one of two genera: Steinernema and Heterorhabditis are commercially available in the U.S. Steinernema is the most widely studied beneficial nematode because it is easy to produce. Heterorhabditis is more difficult to produce but can be more effective against certain insects, such as the white grubs, and Japanese beetles.
How beneficial nematodes work: The life cycle of beneficial nematodes consists of six distinct stages: an egg stage, four juvenile stages and the adult stage. The adult spends its life inside the host insect. The third juvenile stage, called a dauer, enters the bodies of insects (usually the soil dwelling larval form. Some nematodes seek out their hosts, while others wait for the insect to come to them. Host seeking nematodes travel through the soil the thin film of water that coats soil particles. They search for insect larvae using built-in homing mechanisms that respond to changes in carbon dioxide levels and temperature. They also follow trails of insect excrement. After a single nematode finds and enters an insect through its skin or natural openings, the nematode release a toxic bacteria that kills its host, usually within a day or two.
Why are these organisms beneficial?
Parasitic nematodes are beneficial for six reasons. First, they have such a wide host range that they can be used successfully by eliminating over 200 pest insects in the soil. The nematodes' nonspecific development, which does not rely on specific host nutrients, allows them to infect a large number of insect species.
Second, nematodes kill their insect hosts within 48 hours. As mentioned earlier, this is due to enzymes produced by the Xenorhabdus bacteria. Third, nematodes can be grown on artificial media.This allows for commercial production which makes them a more available product.
Fourth, the infective stage is durable. The nematodes can stay viable for weeks when stored at the proper temperature. Keep refrigerated at 37º to 50ºF. They can also tolerate being mixed with various insecticides, herbicides and fertilizers. Also, the infective juveniles can live for some time without nourishment as they search for a host.
Fifth, there is no evidence of natural or acquired resistance to the Xenorhabdus bacteria. Though there is no insect immunity to the bacteria, some insects, particularly beneficial insects, are possibly less parasitized because nematodes are less likely to encounter Beneficial’s which are often very active and escape nematode penetration by quickly moving away. It is important to select the proper nematode species when trying to control a particular pest. Reapplying nematodes depends on the success of the first nematodes released. Their survivorship and success are based on environmental conditions and soil type, increases in original pest population, and percentage of living nematodes released during the first application. Nematodes should be reapplied on monthly intervals if damage continues.
Finally, there is no evidence that parasitic nematodes or their symbiotic bacteria can develop in vertebrates. This makes nematode use for insect pest control safe and environmentally friendly.Though they are lethal to larvae, Beneficial Nematodes are completely safe around people and pets. The United States Environmental Protection Agency (EPA) has ruled that nematodes are exempt from registration because they occur naturally and require no genetic modification.
I would recommend Buglogical Control Systems in placing your order for Beneficial Nematodes.
Click "Here" to place your order at Buglogical.