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Beneficial (entomopathogenic) Nematodes

Steinernema sp.

Heterorhabditis sp.

What is a nematode? They are the most numerous multicellular animals on earth; in fact there are many thousands of individual nematodes in every single handful of garden soil.  They are microscopic non-segmented worms.

 

There are many  kinds of  nematodes, but when it comes to gardening you can break them down into two categories. The bad nematodes can parasitize roots of plants, or cause foliar damage.  These “plant parasitic” nematodes can be of great concern (to you and the state inspectors) if you are shipping plants with soil across state lines.  Then there are the good or beneficial ones; these are the nematodes that are used in modern biological control to combat a wide variety of insect pests.

 

History Using nematodes for biological control is not a recent development.  Ever since the 17th century, nematodes have been known to parasitize insects.  In 1929, researchers Glaser and Fox identified and reared nematodes to potentially control grubs of the Japanese beetle.  One would think this would have set off an era of biological control, but with the development of more economical insecticides, this research was to be put on hold.  Fast-forward to today, and the labs are once again busy.   Environmental contamination, the de-registration of many commonly used chemicals, and resistance management concerns are causing researchers to look at nematodes once again, with promising results. 

 

Beneficial Nematode

Steinernema feltiae

Photo by Jim Cate, Ph.D

More about beneficial nematodes...

Biology- Beneficial nematodes can be broken down into 2 ways in relation to how they hunt prey.  There are the “ambushers” (which include the Steinernema spp). This group of nematodes will sit and wait for an insect host to move by, and then move to force their way into the hosts’ body.  They are very effective against pests that are moving around on the soil surface, such as cutworms, fungus gnats and others.   On the other hand there are the “Cruisers” that will move around actively searching for hosts.  They are usually found deeper in the soil profile attacking many types of grubs.  These are normally in the genus Heterorhabditis spp. 

NEMATODE SPECIES COMMERCIALLY AVAILABLE

Nematode name

Controls

Comments

Heterorhabditis bacteriophora

Weevils and other beetle grubs that live in the soil including Japanese beetle, Masked chaffer, Black vine weevil, Strawberry root weevil, Flea Beetle and more

One of the oldest known and best of the insect parasitic nematodes

Heterorhabditis indica

Citrus root weevil group, May/June beetles, Banana moth, Mole Crickets, Masked chaffer

A species  particularly suited for use in subtropical soils and environments

Heterorhabditis marelatus

Weevils and other beetle grubs that live in the soil including Japanese beetle, Masked chaffer, Black vine weevil, Strawberry root weevil, Flea Beetle and more

Some what more cold tolerant then Heterorhabditis bacteriophora

Heterorhabditis megidis Seeks out the pupa and larval stages of black vine weevil  

Steinernema carpocapsae

Fleas, Armyworm, Cutworm, Fruit fly, Sod webworm, Beet armyworm

Ambusher

Steinernema feltiae

Fungus gnats, Western Flower Thrips,  Fruit flies, Tobacco cutworm, Shore flies, Onion maggot, and more

Ambusher. Being used for WFT control in greenhouse production.

Steinernema riobrave    

Steinernema scapterisci

Mole Crickets

In 1985 S. scapterisci was brought from Uruguay to Florida

Testing Beneficial Nematodes To See If They Are Alive

Tools needed: nematodes, water, small dish, hand lens (10x or better) or microscope

  1. Place a small sample of nematodes on a small plate or petri dish.
  2. Put 1 drop of water on sample.
  3. Wait about 10 minutes, and then look at with lens or microscope.

ALIVE!

Snake-like movement, or nematodes curling in circles (like doughnuts).

 

DEAD

Straight arrow-like appearance.  You can expect to see some dead (most companies pack extra to compensate)

 

See photo to right

Other Nematodes Links  
 
   

 

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