Resistant Parasites: Predatory Fungus Could Aid Control

Predatory fungus Duddingtonia flagrans might be a viable option for the biological control of infective larvae of small strongyles, researchers noted in a recent study.

Adult small strongyles residing in a horse's large intestine and cecum lay eggs that are passed in the feces. The eggs hatch and larvae develop on pasture. Horses become infected when they ingest the third stage larvae (L3) while grazing.

Administration of deworming drugs, called anthelmintics, is the most common method employed for controlling internal parasites in horses; however, resistance to chemical wormers is a major problem. Small strongyles are already resistant to both of the benzimidazoles (oxibendazole and fenbendazole) and also pyrantel pamoate. There is also evidence suggesting that resistance is developing against ivermectin.

"Alternatives are required to help reduce the continued use of the same anthelmintic class," noted the Brazilian research group in a recent study. "Biological control is among these alternatives, using natural nematode antagonistic fungi."

To evaluate the predatory activity of D. flagrans on L3 small strongyles, researchers incubated the fungus in Petri dishes containing a water-agar combination with or without L3s. The plates were examined microscopically every 24 hours for seven days and researchers counted non-predated L3s. A significant reduction (93.64 percent) in the recovered L3s was noted, suggesting that D. flagrans is a potential candidate for the biological control of horses cyathostomin L3.

Reprinted from Horse.com