Steinernema scapterisci — THE BENEFICIAL NEMATODE: HOW TO USE IT

 

What is this nematode?

There are thousands of species of nematodes in Florida. Many of them damage plants and are pests. A few attack only insects. Steinernema scapterisci attacks only pest mole crickets, reproduces in them, and its progeny are released into the soil when the mole cricket dies. Furthermore, it attacks the adults and large immature stages of these mole crickets, not the small immature stages. It is a tiny (microscopic) nematode harmless to all organisms except pest mole crickets. It is native to South America where Florida's pest mole crickets originally came from.


Where is this nematode?

Steinernema scapterisci nematodes were imported from Uruguay by University of Florida/IFAS nematologists in 1985. They were released in Alachua County and they began to spread. Then it was found that this nematode could be grown in commercial quantities on an artificial diet. That allowed it to be applied to pastures and turf in many places. Nobody has a record of all the places where it has been applied, and of course it has spread from some of those places. The University of Florida currently holds a patent on use of this nematode to control pest mole crickets. NOTE: The nematode is currently unavailable for sale. When a supplier becomes available we will provide a link.


Is this nematode already in your pasture?

If you or someone else already applied this nematode to your pasture or to another pasture close by, the chances are that it is still present, so there is no point applying more. How to check for its presence? In February-April or in September-November, take the following steps.

  1. Contact your participating county Livestock Extension agent and inform him or her, and obtain a supply of plastic snap-cap vials. [Livestock Extension agents: please make sure you have a supply of these vials to hand out - contact NCLeppla@ufl.edu].
  2. Assemble these vials in a cooler chest with a cold Ice-Pak.
  3. With a tractor-mounted blade, peel back some turf in an area where you suspect there are many mole crickets, grab at least a couple of dozen of these mole crickets, and put one into each of a couple of dozen vials.
  4. Get the vials in the chest to your participating Livestock Extension agent within a day, with your name and phone number (and e-mail address) and the date of collection and exact location.
  5. The vials and information will be shipped to Gainesville by your participating Livestock Agent for determination of the presence of beneficial nematodes in the mole crickets.
  6. You (and your participating Livestock Extension agent) should have an answer within two weeks. This may take all of two weeks to process because there is no quick and easy test.

What is involved in planning an application?

There are three important things to do. First, decide whether you want to apply nematodes. Second and third, in collaboration with your participating Livestock Extension agent, order the appropriate quantity of nematodes from Becker Underwood, and schedule use of an application machine. Applications should be made only in February-April or in September-November when mole crickets are large and active. (In the summer months they are small, and in the winter months they may be deep underground in cold weather). Set the application depth to between 1 inch and 2 inches (not shallower, not deeper). 


What is the appropriate quantity of nematodes?

How many acres do you want to treat?  You will need one (1) billion nematodes per eight (8) acres treated. You would treat the eight acres in strips - one strip treated, seven untreated, one treated, and so on. That cuts the cost of the nematodes by 7/8 as compared with treating a solid eight acres. It works because the nematode is a living organism that spreads in time to cover the entire eight acres. The method is described in the UF/IFAS publication on Timing the application of beneficial nematodes to mole cricket activity on pasture to optimize control.


Where can I get an application machine to apply the nematode?

Two application machines are available for loan, one with a trailer hitch and one with a 3-point hitch. Each has a trailer for hauling it by road. One is based at the UF/IFAS Range Cattle Research and Education Center at Ona, Hardee County. The other is based at the Hastings Research and Demonstration site, in St. Johns County. Talk to your Livestock Extension agent if you want to borrow and s/he will make the arrangements. 


Questions and answers

Q. Another company offers beneficial nematodes that they say will kill mole crickets. Why should I not use them?
A. You could, but they work only once before they die because they do not reproduce in pest mole crickets. It is much better to use Steinernema scapterisci because it should establish a permanent population in your pasture, and keep working for years and years. It is available only from Becker Underwood under the name Nematac™ S.

Q. Is it ok to put a package of the nematodes in my freezer for later use?
A. No, freezing temperatures will kill them. It is, however, a very good idea to keep the nematodes in your refrigerator (about 41 degrees Fahrenheit) until you need them, but plan to use them within a few weeks after you receive them. Don't even think about leaving a package of them on the seat of your truck because the heat will kill them - transport them in a cooler chest with a cold Ice Pak.

Q. Is it ok to apply the nematodes in water with a spray boom?
A. It might work late in the day during light rain, or if you can irrigate your pasture before and after application. The safest way is to use an application machine to get those nematodes down into the soil where they won't be harmed by intense sunlight as the ultraviolet light and heat kill the nematodes.

Q. If I fill the tank of the application machine with water, open the package of nematodes, am I set to go?
A. No. It is better to take along a bucket, and mix the nematodes thoroughly in water in the bucket with a stick, and then pour into the tank. Also, it is a good idea to check the calibration of the application machine - make sure it will deliver the full tank of water (with all the nematodes) in the strips that you plan to treat at the speed you plan to drive. And cut off delivery as you turn at the end of each strip, to start up again at the next strip.

Q. The nematode is microscopic, so how does it spread in a pasture?
A. Mole crickets infected by the nematodes still move (or even fly) about the pasture until they become too sick to do so. In this way, the mole crickets help disperse the nematodes to other areas, such as the pasture strips that you did not treat.

Q. Why can't I use the soap-flush method to collect mole crickets to be checked for nematodes?
A. That method may kill the mole crickets and the nematodes. Living nematodes are required for identification. If you go lightly with the detergent (not more than one tablespoon of detergent per gallon of water) and then wash off the mole crickets that you catch in clean water before putting them in vials, you may get away with it.

Further reading:

Timing the application of beneficial nematodes to mole cricket activity on pasture to optimize control.

Infectivity and persistence of Steinernema scapterisci nematodes on pasture mole crickets in Florida.

How to use Nematac™ S against pest mole crickets in pastures.

Operator’s manual for beneficial nematode applicator. NOTE THAT THIS IS TO BE AN EDIS PUBLICATION BUT STILL IS INCOMPLETE.

Mole cricket nematode.