Nematicidal effect of freshwater fungal cultures against the pine-wood nematode, Bursaphelenchus xylophilus

Twenty-two filtrates and 13 water-soluble extracts of broken fungal mycelia from 130 freshwater fungal cultures were found to be pathogenic to the pine-wood nematode, Bursaphelenchus xylophilus following 48 hours exposure in vitro screening. The mobility of over 90% of nematodes were inhibited by filtrates from Ophioceras commune (97.18%), Pseudohalonectria adversaria (96.49%), Pseudohalonectria lignicola (96.15%), Massarina thalassioidea (93.2%), Caryospora callicarpa (95.2%) and Annulatascus sp. (96.12%) and the mycelia extracts from Helicomyces roseus (98.95%), Phomatospora berkeleyi (94.96%) and Pseudohalonectria lignicola (95.59%). Aliphatic extracts of four freshwater fungal solid state fermentation products were found to immobilize over 50% of nematodes within a 12 hour exposure period at a concentration of 40 mg/mL. It was also observed that the aliphatic extracts of Pseudohalonectria adversaria, Xylaria sp. and Hyphomycete sp. were nematicidal, whereas Massarina bipolaris, Caryospoia, callicarpa and an unidentified strain were found to be narcotic in nature because nematodes revived when they were transferred to sterilized water. When screening for nematicidal activities it is important to use approximate neutral and saline environments similar to the natural habitats of the test nematodes, as nematodes can be affected by extreme pH and high osmotic pressure.