FAQ about Beneficial Nematodes on Buglady Consulting

Frequently Asked Questions About Beneficial Nematodes

What are nematodes?

Nematodes are very small, worm-like organisms, most of which are found living naturally in the soil.

What so I buy beneficial nematodes?

Click here for a list of suppliers. Suppliers of beneficial nematodes.

Why are these nematodes considered to be beneficial?

This group of nematodes attack and kill insects, mostly pests. They are safe to use since they do not endanger people, pets, or other desirable animals, even earthworms. Using living, natural biological control agents sustains and augments the natural soil diversity conserving other beneficial organisms that make healthy soils.

Are all nematodes beneficial?

Most nematodes are beneficial. If they are not part of the group that attacks insects, they likely belong the vast majority that are saprophytic, breaking down organic materials adding to richness and tilth of soil and helping to produce high quality compost. There are certain groups of nematodes that attack living plants, plant parasitic nematodes. Also, there are groups of nematodes that parasitize animals.

The insect parasitic, beneficial nematodes that we produce and sell are strictly parasites of insects and have been exempted from registration as pesticides by the U.S. Environmental Protection Agency because of their host specificity and their general safety for humans and the environment.

How do insect parasitic nematodes work?

The nematodes live in the soil where they locate their hosts. The nematode infective stage enters the insect and begins to feed on its blood and internal organs. Soon after it begins to feed, it releases unique bacteria that it carries internally. The bacteria infect the insect, reproduce quickly, and kill the insect within 30 to 48 hours. The nematode thrives upon this food which becomes a decaying insect being broken down by the unique bacteria. The nematode forms an adult stage and begins to produce thousands of eggs. These eggs mature and about 2-3 generations of nematodes are produced in the decaying insect. Reproduction continues until the nematodes sense that the decaying insect will not support further reproduction by the nematode. At that time, all of the nematode offspring mature only to the infective juvenile stage and begin to emerge from the host insect to look for more viable, live insects to infect. The infective juvenile, IJ3, is the third nymphal stage of the nematode which has a double thick skin and which is best equipped to survive in nature until it can find a new host.

Are the bacteria in the nematode harmful to people or pets?

No. The bacteria and the nematode have what scientists call a “symbiotic” relationship. Neither can live without the other. The bacteria are not found in nature outside of the nematode or outside of the infected insect host of the nematode. Likewise, the nematode cannot live on insects alone, but must have food that is “digested” by the bacteria.

Beneficial Nematode - Steinernema feltiae

Photo by Dr Jim Cate

Are the bacteria always present in commercially produced nematodes?

Yes and Not Always! This is a very important quality control issue. Yes, if the nematodes are produced on live insect hosts. By producing nematodes on live insect hose, the offspring always consume and store the bacteria produced by their parents in the host insect from which they emerge.

Not always, if nematodes are produced by artificial fermentation on artificial media. When producing nematodes by artificial fermentation the bacteria are cultured separately from the nematode, introduced to the media before bacteria-free nematode are introduced. If every thing goes as it should, the offspring will contain the proper bacteria in the proper amounts. Under this kind of production, a major quality control operation is to test the quality of the bacteria and to test the product after production to assure that it contains the correct bacteria and an appropriate amount of bacteria.

What kind of equipment is needed to apply beneficial nematodes?

These nematodes can be applied using the usual application equipment: recirculation pump sprayer, pump-up garden sprayer, watering can, hose-end sprayer, or injection into irrigation systems.

How are the nematodes handled in preparation for application?

It is very important that the nematodes are living organisms so they must be kept out of direct sunlight and kept cool until they are applied. They should be stored in the refrigerator or a cold box at 50° to 65° F. from time of receipt until they are being prepared for application.

Nematodes will settle to the bottom of applicator tanks so it is very important to agitate or shake the tank every 15 to 20 minutes to assure that the nematodes are uniformly suspended in the water. Commercial sprayers having by-pass pressure regulation provide very good agitation of the water and do not require shaking or further agitation.

Nematodes are very hardy and can safely tolerate 100 to 150 pounds of pressure, but they can be damaged if pumped through filter screens that have mesh sizes smaller than 30. For best results, remove all filter screens.

Nematodes can drown, so it is important to make sure that the entire volume of spray in a tank is applied without delay.

Nematodes can safely tolerate a pH range from 5 to 9, but be careful of use of highly sulfonated water that depletes the oxygen upon its first exposure to the air. They can be tank-mixed with many insecticides, fungicides, fertilizers, and soil amendments. Normal chlorine amounts found in drinking water do not harm the nematodes.

What kind of site preparation is needed prior to application?

Again, beneficial nematodes are living organisms that live naturally in the soil. UV radiation and desiccation are the two greatest enemies to the nematode. Consequently, it is important that the soil or site to which the nematodes will be applied is damp and not dry. If the site to be treated it dry, one may apply a greater amount of water with the application to compensate. After the application is completed, we recommend that the treated area be irrigated with a moderate volume of water to assure that the nematodes have sufficient water to move them down onto and into the soil. It is best if applications can be made either early or late in the day to take advantage of lower sunlight strength and cooler temperatures.