In Vitro Ovicidal Activity of Nematophagous Fungus Paecilomyces lilacinus on the Eggs of Parasitic Helminths

Introduction: The nematophagus fungi have been suggested as an alternative way to eliminate the zoonotic helminths eggs from the environment. In the present study, we evaluated the ovicidal activity of a fungus, Paecilomyces lilacinus, recovered from a compost soil, on the eggs of parasitic helminths under in vitro condition. Methods: Water suspension of the soil samples collected from different areas of Iran were transferred to 2% water-agar culture media baited with Rhabditis sp. larvae. The larvae-infecting fungi were harvested on potato dextrose agar (PDA) media. The sequencing of a beta-tubulin gene identified the nematophagus fungi as P. lilacinus. Eggs of three helminth species, Syphacia obvelata, Hymenolepis diminuta and Echinococcus granulosus were exposed to one isolate of the recovered fungi, and the ovicidal activity was monitored for up to 21 days. Results: Out of 300 samples, only three compost soils, contained the nematophagus fungus P. lilacinus. Microscopical examinations revealed invasion of the helminths eggs by the P. lilacinus. The eggs of H. diminuta were more vulnerable to this fungus invasion while E. granulosus eggs were the least affected ones (P<0.05). Conclusion: Paecilomyces lilacinus can grow on fresh feces and attack the eggs of the parasitic helminths. Therefore, a combination of its hyphae with feces or administration of the spores in the animals&rsquo; food may reduce the helminths eggs in the environment and consequently intervene with the transmission of parasitic helminthes in the animal houses.