Australasian Association of Nematologists
Recent studies on Paecilmyces lilacinus as a bionematicide. Suppression of Heterodera avenae populations, infection of Meloidogyne javanica eggs, females and juveniles in a pot trial and Radopholus similis eggs in laboratory studies.
M. M. Alamgir Khan, R. J. Holland and K. L. Williams, School of Biological Sciences, Macquarie Universty, Sydney
Currently, biocontrol offers an alternative approach for controlling plant parasitic nematodes, considering the innate problems related to the pollution hazards of chemical control. Among opportunistic soil Hyphomycetes consistently associated with the pathology of cyst and root knot nematodes in some parts of the world and known to be an effective egg parasite is Paecilomyces.
We have shown effective control of cereal cyst nematode, Heterodera avenae, by P. lilacinus (BIOCAT strain 251) in a pot trial. Nematode populations were drastically reduced by P. lilacinus in both sterilised and unsterilised soils. At harvest, 80% of white cysts were found infected with the fungus. Eggs from highly infected cysts were found to be infected by P. lilacinus when incubated at 26°C in the lab on semi-selective medium.
Light microscopy, scanning electron microscopy (SEM) and
transmission electron microcopy (TEM) are being used to study the infectivity and mode of
penetration of various life stages of H. avenae, M. javanica, and R.
similis by P. lilacinus. Excised M. javanica females, 3rd and
4th stage juveniles and egg masses were inoculated with P. lilacinus and
both females and juveniles became infected. The fungus had penetrated the female through
the body wall as shown by TEM micrograph. Eggs within infected female and 1st
and 2nd stage juveniles (from egg mass) were infected with fungus. Unhatched 2nd
stage juveniles were found covered with mycelium within the eggs but the fungus was not
observed within the larvae. However with time lapse imaging, 2nd stage
unhatched juveniles were later found to be full of fungal hyphae, with no sign of the
pre-existing juvenile. Infection of R. similis eggs only occurred after prolonged
exposure to P. lilacinus. To better understand the efficacy of P. lilacinus against
R. similis we are undertaking a port experiment with banana plants.
