Survival of the elm nematode Bursaphelenchus ulmophilus in cultures of insect-dispersed fungi

What is it about?

Several fungi found on vector beetles and nematodes were found to be capable of maintaining a high population abundance of the pathogenic nematode Bursaphelenchus ulmophilus, associated with Dutch elm disease, at a temperature of 25°C without frequent re-cultivation and for a long period (6 months). The fungi used as substrates for the nematode cultivation were originally isolated from the natural vectors, beetles and nematodes, identified by ITS1/2 and 5.8S or elongation factor 1-alpha genes. Mucor hiemalis and Alternaria alternata were the best substrates for maintaining nematode abundance. Species of the genera Trichoderma, Ophiostoma and the species Graphium radicatum were good substrates. Previously, Trichoderma spp. were characterised as potential biocontrol agents for Bursaphelenchus spp. in short-term experiments. The laboratory non-sporulating isolate of Botrytis cinerea, the fungi Sydowia polyspora and Leptographium piceardum do not support long-term propagation of B. ulmophilus.

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Why is it important?

Some woody plants diseases are caused by a nematodes and fungi vectored by bark beetles. Trophic relations of the vector-born fungi and their nematode partners on beetles are not sufficiently studied, especially the nematode survival in the fungal mycelium after the plant death. The results can be used for economical long-term storage of live nematode cultures of Bursaphelenchus spp. and species of the phylogenetically related Aphelenchoididae.

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