Screening for new nematocidal substances of microbial origin by a new method using the pine wood nematode.

Parasitic diseases are widespread, currently affecting about 3 x 109 people and innumerable domestic animals.0 Nematodes (round worms) are a group of most important parasitic organisms. Many attempts have been made to find potent nematocidal substances, however, only a few antibiotics are available in practice.^ Recently, avermectins, which have a potent nematocidal activity and are used in the veterinary fields, were discovered by the in vivo screening method using mice infected with Nematospiroides dubius.3^ Kimura et aL5) devised a method to distinguish alive nematodes from dead ones, which is based on the nature of living nematodes that descend through Japanese paper. We attempted to develop a screening method for nematocidal antibiotics using the pine wood nematode Bursaphelenchus lignicolus by Kimura's method with modifications. Consequently, a more rapid and simple methodwas successfully established and then used for prac-