Researchers tested five types of fungi that naturally attack insects to see if they could control Ascaris roundworm eggs that contaminate pig farms and pose health risks. While none of the fungi directly killed the eggs, two species (Isaria fumosorosea and Metarhizium robertsii) successfully slowed egg development and showed potential for controlling parasites. These fungi appear to work by producing toxic compounds and enzymes rather than by penetrating the egg shells directly.