The right combination of compounds produced by a
beneficial fungus could lead to grasses that require fewer pesticides and are
safer for wildlife and grazing animals, according to Purdue University
scientists.
Neotyphodium is a fungus called an endophyte. It lives
symbiotically, feeding off many species of grasses while providing the grass
with protection from insects such as black cutworm. But Neotyphodium also can
be toxic to animals based on the types of alkaloids it produces. It was once a
serious concern for pasture managers.
Scientists have previously eliminated alkaloid profiles
that caused toxicity in livestock, meaning pasture managers could feed their
livestock without making them sick. But in making the grasses safe for animals,
their susceptibility to insects came into question.
“These endophytes have changed everything for farmers
who let their animals graze,” says Douglas Richmond, a Purdue assistant
professor of turfgrass entomology and applied ecology. “But they created
another potential problem.”
Richmond worked with
researchers in New Zealand
to assemble a series of Neotyphodium endophytes that are safe for livestock
consumption and tested them to see which would also act as natural
insecticides. They found a relatively few strains of the fungus that meet both
criteria by producing two key alkaloid toxins—N-acetyl norloline and peramine—which
are a product of the fungal metabolism. The scientists determined they were
effective by characterizing insect growth and survival on grasses with different
alkaloid profiles.
Richmond
said that grasses naturally infected with the desired endophyte strains can now
be propagated for commercial production.
“Both are relatively safe for mammals and other
grazing wildlife,” Richmond
says. “Now the seed industry can put these endophytes into turf and
pasture grasses and not worry about potential non-target effects.”
Those endophytes also mean that farmers, golf course turf
managers, and even homeowners caring for their lawns could use fewer
insecticides to manage their grasses.
“I think this is going to be very important for
sustainability. It’s going to decrease the footprint of cultured turf and
pasture grasses,” says Richmond,
whose results were published in the Journal
of Environmental Entomology. “And if you like having wildlife around—having
deer come up to your lawn if you live near the woods—this is a benefit because
it’s safe for those animals.”
Richmond says he is working
with a New Zealand company,
AgResearch USA Ltd., that develops turfgrass varieties to include these novel
endophytes for sale in the U.S.
turfgrass market.
