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 their recent study. "Biological control is among these alternatives, using natural nematode antagonistic fungi