Development time and survivorship of Deladenus siricidicola (Tylenchida: Neotylenchidae) on different strains of Amylostereum areolatum (Russulales: Stereaceae)

The invasive pine woodwasp Sirex noctilio (Hymenoptera: Siricidae) can infest and kill healthy pine (Pinus spp.) trees. It owes this success to a symbiosis with a tree pathogenic fungus, Amylostereum areolatum, which the woodwasp injects into pine trees during oviposition. The parasitic nematode Deladenus siricidicola has been used successfully for biological control of S. noctilio in the Southern Hemisphere. D. siricidicola has a parasitic form and a fungal-feeding form, the latter of which is used for mass production. Because a different strain of A. areolatum is used by native woodwasps in North America, D. siricidicola used for control of S. noctilio in the United States might grow on it at a different rate, affecting control. This study focused on the hatching rate of eggs of D. siricidicola. Eggs were then inoculated onto plates of several strains of A. areolatum, which grow at different rates, to test the nematode’s ability to grow on the strains. It was found that too much fungal growth results in nematodes being overgrown by fungus, and too little fungal growth results in nematodes running out of food. Thus, presence of other strains of A. areolatum could affect the effectiveness of D. siricidicola in the United States.