(Beyond Pesticides, October 9, 2009) An Australian Government study has shown that lice on sheep may be controlled by fungal biopesticides. Scientists from Queensland Primary Industries and Fisheries (QPIF) in Queensland, Australia have achieved promising results using a naturally occurring fungus called Metarhizium isolated from Queensland soil as an insecticide.
“When the fungal spores are applied to the sheep, they stick to the surface of lice as they move around in the fleece,” explains QPIF Senior Scientist Diana Leemon, PhD. “The lice also consume spores as they feed on wool grease and the spores germinate inside the insect, killing it.”
Tim Mulherin, Minister for Primary Industries, Fisheries and Rural and Regional Queensland, stated, “Livestock industries, including sheep, are extremely important to our economy. Parasites such as sheep lice damage wool and reduce yields, leading to significant losses for the producer. Lice cost the Australian wool industry $123 million annually through lost production and control costs.”
QPIF and Australian Wool Innovation Limited (AWI) have signed an agreement with commercial partner Becker Underwood Australia to develop the biopesticide to help the lice problem. AWI CEO Brenda McGahan said the research was timely as sheep lice are building resistance to some current treatments. “Producers are reporting sheep lice are becoming a major problem, particularly following a recent ban on the use of the effective insecticide diazinon in a wet dip.”
Fungal biopesticides have shown potential as insecticides of other bugs as well. Recently, researches worked with fungus as an insecticide for crickets and grasshoppers. The research team, led by USU insect pathologist Donald Roberts, PhD, is analyzing 10,000 soil samples gathered by the U.S. Department of Agriculture (USDA) in 17 states. After isolating the various fungi, each is grown in the lab and tested individually.
Some fungi are more effective than others as pesticides. Paul Stamets, a mushroom expert who spoke at the 2006 Beyond Pesticides National Pesticide Forum in Washington, DC on how fungus can play a part in insect control, has provided much research to the field of fungal pesticides, providing invaluable information on breeding fungus and fungus’ pesticidal usages. The green mold fungus Metarhizium anisopliae seems to be one effective fungal pesticide during certain phases of its life. One problem is that insects are sensitive to the spores and avoid them, and soldier insects guarding nests sense and intercept most spore-contaminated foragers to prevent them from entering and infecting the colony. Strains of the fungus produce chemical attractants in the mycelial state, the stage of the life cycle when a fuzzy mat of mycelium protrudes from a dead carpenter ant, making the mycelium an effective biopesticide.
Fungi found in soil are a less toxic solution to certain insect problems. Beneficial fungus pathogens, Beauveria spp., is a fungus that is used as a pesticide for controlling many kinds of insects. Many strains of this fungus are found worldwide in the soil. They control insects by growing on them, secreting enzymes that weaken the insect’s outer coat, and then getting inside the insect and continuing to grow, eventually killing the infected pest. Available EPA information indicates that use of Beauveria spp. as a pesticide is not expected to adversely affect people or the environment and tests show that the fungus is not toxic to mammals, birds or plants. There is a potential for pesticide products containing the fungus to harm bees, so the products must not be applied near beehives or where bees are actively hunting for food.
As the demand for organic products (including raw textile materials such as cotton and wool) grows, producers are looking for organic pest control options. As Richard Waterworth, Director of Becker Underwood Australia says, “Given the increasing demand for low residue and organic wool, we believe this form of lice management will become mainstream.” Many consumers now want to buy organic, chemical free materials; not just food. With advancements of this sort, the accessibility of organic products will increase.
Mr. Stamets and his colleagues have been working with fungi that feed on insects, and he has figured out a way to grow fungi that delay their spore formation and actually attract the insect to the fungus, thus breaking through an obstacle in using fungi to protect homes from carpenter ants and termites. However, in doing so, he says his philosophy “is not to wage war against the insect kingdom but to enlist fungal allies for the intelligent, natural, and localized control of targeted insects”¦ We seek balance, not extinction.” Beyond Pesticides offers a video of Mr. Stamets’ speech and the article, “Fungi to the Rescue: Biopesticide derived from mold has promise as a greener method for eradicating unwanted insects,” in the Winter 2007 issue of Pesticides and You.
Source: Media Newswire