Mode of Action

General note

BioAct^® is a biorational pesticide and is quite different from conventional synthetic chemical pesticides.  Biorational control agents are generally recognised as a special class of pesticides since they pose a lower potential hazard than conventional pesticides.  They target specific species in a mode of action which is generally not toxic and has no adverse environmental effects.  The biological control agent Paecilomyces lilacinus is also found in nature.

Mode of action

BioAct^® is made up of the spores of the naturally occurring fungus Peacilomyces lilacinus, strain PL 251.

The fungus PL 251 is strongly parasitic to all stages of development of common plant infecting nematodes, especially the eggs.  Spores of the fungus also adhere to the cuticle of vermiform stages of the nematodes as they migrate through the soil.  The spores germinate.  The growing fungus penetrates the cuticle and engulfs the nematode.  The hyphae of the fungus can also enter the nematode through body openings, such as the anus and vulva.  The developing fungus kills the nematode by feeding on its body contents.  In effect, the fungus acts as a parasite on the nematode.

BioAct^® infects the eggs of root knot nematodes and progressively destroys them over a period of several days.  Adult females are also readily infected.  In one test, almost 80% of adult females were parasitized after six days.  In another test after treatment all adults of the burrowing nematode (Radopholus similis) were found infected and immobilised within six days.

Picture (by courtesy of USDA, ARC, Nematology): Female soybean cyst nematode (Hetorodera glycines spp.) with egg mass (right).