Relative ovicidal effect of soil microfungi on thick-shelled eggs of animal-parasitic nematodes

Summary in the original language of the document

Thick-shelled eggs of animal-parasitic ascarid nematodes can survive and remain infective in the environment for years. The present study was conducted to assess the effect of two species of soil microfungi (Pochonia chlamydosporia and Purpureocillium lilacinum) on the development and survival of eggs (all of faecal origin) of three ascarid species, Ascaridia galli (chicken roundworm), Toxocara canis (canine roundworm) and Ascaris suum (pig roundworm), in vitro. Ascarid eggs were embryonated on water agar with or without one fungal species, and viability of the eggs was evaluated on days 7, 14, 21, 28, 35 and 42 post set up (p.s.). By day 14 p.s., P. chlamydosporia had reduced the viability of A. galli and T. canis eggs by 70-86% and 52-67%, respectively, compared to controls without fungus. In contrast, P. lilacinum had reduced the viability of A. galli and T. canis eggs by only 17-30% and 6-28%, respectively. Ascaris suum eggs were extremely resistant to both fungi. The differences in results are likely due to the variability in egg shell morphologies of the three ascarid species. The current in vitro study demonstrates that P. chlamydosporia may potentially be utilized as a biocontrol agent to reduce A. galli and T. canis egg contamination of the environment.