Evaluation of soil microfungi as biological control agents against eggs of animal parasitic nematodes

Thick-shelled eggs of ascarid nematodes have been reported to remain infective in the environment for several years, thus posing a prolonged risk of infection to animal livestock and/or humans. An in vitro study was therefore conducted to evaluate the negative impact of two species of soil microfungi, Pochonia chlamydosporia and Purpureocillium lilacinum (syn. Paecilomyces lilacinus), on the viability of Ascaridia galli, Toxocara canis and Ascaris suum eggs. Approximately 150 fresh eggs of individual ascarid species were embryonated on a 2% water agar in Petri dishes with or without a fungus (P. chlamydospria or P. lilacinum). On days 7, 14, 21, 28, 35 and 42 post experimental set up (p.s.), the viability of the eggs from each experimental group was evaluated (destructive sampling). 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 the controls. In contrast, P. lilacinum had reduced the viability of A. galli and T. canis eggs by only 17-30% and 6-28%, respectively. Neither fungal species was found to be effective against A. suum eggs (