Before nematodes or eelworms, which infect the roots of agricultural crops, were controlled by applying synthetic nematicides to the soil. These chemicals, however, are highly toxic, disrupt the natural soil ecosystem, and can cause serious environmental problems.
In the course of finding alternative control measures, a team of Filipino nematologists led by Dr. Romulo G. Davide, then professor of Plant Pathology in the University of the Philippines Los Banos (UPLB), thought testing the capability of the fungus Paecilomyces lilacinus Strain 251 (PL 251) as a biological nematicide.
PL 251, which in 1980 can only be found in the Philippines, is parasitic to all stages of development of common plant-infecting nematodes particularly root knot, potato cyst, and spiral and burrowing nematodes. In their vermiform stages, nematodes are infected as they migrate through the soil. The infection starts when a spore of the fungus adheres to the cuticle and then germinates. The growing fungus then overwhelms the nematode and eats its body.