Be st Ma na ge me nt Pr acti ce s fo r Int er na l Pa ra site Contro l i n Sma ll Rumina nts

Worm-trapping Fungus
FEBRUARY 2021

A common question is “How can pastures be cleaned

up to reduce transmission of gastrointestinal
nematodes (worms)?” Nematode-trapping fungus
may be the answer.

THE WORM LIFE CYCLE

To understand how nematode-trapping fungus might
help, a basic understanding of the worm life cycle is
necessary. Briefly, the worm life cycle consists of two
parts: one that takes place inside the animal and one
that occurs on pasture. Adult worms reside in the
gastrointestinal tract of the animal and after mating,
female worms lay eggs that are passed out in the
feces. The eggs hatch in the feces and develop
through two larval stages until reaching the third Ninety percent of the worm population resides on pasture.
larval stage that migrates out onto the surrounding
vegetation where it is ready to be consumed by
grazing animals. Once ingested, the larvae develop HOW THE FUNGUS WORKS
into adult worms (which do damage to the host
animal) and the life cycle is complete. Nematode-trapping fungi have been shown to be
efficient biological control agents against the worm
When an animal is dewormed, worms inside the
larvae in livestock feces. These fungi are found
animals are eliminated which reduces the number of
naturally in environments that are rich in organic
worm eggs that are passed in the feces to
matter where they produce a variety of mycelial
contaminate the pasture. The more worms that
(vegetative part of the fungus) structures that trap,
dewormers kill, the fewer the number of eggs on
destroy, and feed on non-parasitic soil worms. Spores
pasture, but eventually worms become resistant to
of various species of these fungi have been isolated,
dewormers and egg shedding returns to higher levels.
concentrated, and introduced into feces that contain
Reliance on dewormers for worm burden within the
developing gastrointestinal worm larvae. Of those
animal and on the pasture has proven to be
investigated in livestock, Duddingtonia flagrans
unsustainable.
spores (Figure 1) have the best ability to survive
Besides deworming, there are other strategies to help passage through the ruminant gastrointestinal tract.
reduce worm burden and egg shedding, including When passed in the feces, D. flagrans spores
copper oxide wire particles (COWP), forages germinate. The mycelia grow rapidly into sticky,
containing condensed tannins (e.g. Sericea sophisticated traps/loops that trap and digest larvae
Lespedeza), and genetic selection for resistance to (Figure 2).
parasites. But they also have limitations. In addition,
The trapping structures are usually present within the
all these approaches target the worms in the animal.
first few hours after defecation, and a sticky
Until recently, there was no proven product on the
substance is present within 48 hours to help with
market to specifically target the worm burden on
larval contact, followed by hyphal cuticle penetration
pasture. Nematode-trapping fungi may be the first.
(Figures 3 and 4). The moving parasitic larvae are

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trapped by the structures of the mycelium. Once the

larvae are trapped, the hyphae penetrate the larval
cuticle and grow, filling the body of the larvae and
digesting the contents. Most importantly, trapped
larvae are unable to migrate out of the fecal mass and
onto plant material that could be consumed by the
grazing host animal. Fewer larvae on pasture result in
healthier animals.

FEEDING THE FUNGUS

Figure 1. D. flagrans spore
The primary delivery system of the spore material is
thorough mixing with supplemental feedstuffs which
provides a continuous source of the fungus in the
feces. Daily feeding so that each animal consumes an
adequate amount of the feed/spore mixture is
necessary. Another delivery system would be
thoroughly mixing the fungal spore material into a
loose mineral supplement. The mineral would need
to be kept covered and dry. This method does not
require daily feeding, but the mineral supplement
would need to be available and regularly consumed
to provide a constant source of spores for the
Figure 2. D. flagrans trapping network duration of the treatment period. There has been
little research on this method, but it would provide a
good alternative for producers who do not provide
supplemental feed to their livestock. Unfortunately,
the spores cannot be incorporated into pellets or
cooked blocks as the heat of the pelleting process
will kill the spores.
To achieve adequate control of larvae in the feces
during the transmission season (May-October for
most US areas), spores would need to be fed for a
period of at least 60 to 120 days. Feeding should
commence with the beginning of the grazing season,
Figure 3. D. flagrans 8 hours post-capture especially for young freshly weaned livestock.
Similarly, to help curb the periparturient egg rise,
feeding spores to females during late pregnancy and
lactation should help to reduce pasture
contamination for lambs/kids that graze the same
pastures with their dams. Feeding studies with sheep,
goats, and cattle have shown a reduction of 68 to 86
percent of larvae in feces and on pasture. Fecal egg
counts can be expected to decrease over time due to
the reduced reinfection. During periods of drought or
low transmission (winter and other non-grazing
periods), it would not be necessary to feed spores as
there would already be a reduced amount of larvae in
Figure 4. D. flagrans 48 hours post-capture
the feces. There would also be no need to feed the
spores to animals being raised in confinement, since
Micrographs copyright International Animal Health there is little to no source of parasitic infection.
Products Pty Ltd, reproduced with consent
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Both products are the only control method that

specifically targets the worm population on pasture,
where the majority (estimated at more than 90
percent) of the total worm population resides during
the parasite season. This form of control has been
successfully applied under field conditions and is an
environmentally-safe, biological approach for
pasture-based livestock production. When
introducing anything new into the environment, the
long-term effect on trapping advantageous native
free-living worms that help recycle fecal matter also
needs to be considered. It has been demonstrated
that D. flagrans had no adverse effect on such
advantageous worms, and the fungus was no longer
detectable in the environment two months after
Goat eating BioWorma® image by Lisa Williamson treatment.

In the US, two formulations of Duddingtonia flagrans It is important to understand and emphasize that
are FDA-approved and commercially available: these products are just one component of an
BioWorma® and Livamol® with BioWorma®. Livamol® integrated parasite control program and should not
with BioWorma® is a protein supplement that can be be relied on alone for gastrointestinal worm control.
mixed with other feed supplements or top-dressed One still needs to address the worm population in the
over feed. Anyone can purchase and feed Livamol® animal using the targeted selective deworming
with BioWorma©. BioWorma® is a concentrated feed approach to conserve longevity of effective
additive that is meant to be mixed with other feeds or dewormers.
supplements. Its distribution is limited to
veterinarians and EPA-certified feed manufacturers.
The cost of feeding BioWorma® is relatively expensive
Nematode trapping fungi are the
compared to dewormers, but the long-term benefit of first product to specifically target
reduced pasture contamination is a factor that must
be considered. In addition, it is possible that research
the worm population on pasture.
will determine more cost-effective ways to utilize
BioWorma©. For example, feeding BioWorma© every
other day or for two weeks out of the month would For more information about BioWorma®, go to
reduce cost by half if it is proven to be as effective as www.bioworma.com or www.duddingtonia.com.
daily feeding.

AUTHORS: REVEIWERS:
Joan Burke Ph.D. Kwame Matthews, Ph.D. Susan Schoenian, M.S.
USDA ARS, Dale Bumpers Small Delaware State University University of Maryland,
Farms Research Center Dover, Delaware Keedysville, Maryland
Booneville, Arkansas
Reid Redden, Ph.D. Niki Whitley, Ph.D.
Jim Miller DVM, Ph.D. Texas A&M AgriLife Fort Valley State University
Louisiana State University San Angelo, Texas Fort Valley, Georgia
Baton Rouge, Louisiana

For a complete list of fact sheets, go to https://www.wormx.info/bmps.

Fact sheets in the Best Management Practices for Internal Parasite Control in Small Ruminant series were written and reviewed by members of
the American Consortium for Small Ruminant Parasite Control. They are for educational and informational purposes only. No practice de-
scribed in the fact sheets stands alone as a method to control internal parasites. Each producer needs to implement the appropriate combina-
tion of practices that will achieve satisfactory control of internal parasites in their flock or herd. The fact sheets are not meant as a substitute
for professional advice from a veterinarian or other animal science professionals. Some treatments described in the fact sheets may require
extra label drug use, which requires a valid veterinarian-client-patient relationship.

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