Suppression of an entomopathogenic nematode by the nematode-trapping fungi Geniculifera paucispora and Monacrosporium eudermatum as affected by the fungus Arthrobotrys oligospora

Abstract

In soils of a coastal shrubland, nematode-trapping fungi may influence the distribution of the entomopathogenic nematode, Heterorhabditis hepialus. In previous studies with shrubland soil, Arthrobotrys oligospora was the most common fungus, followed by Monacrosporium eudermatum and Geniculifera paucispora, and all three fungi suppressed H. hepialus when tested individually in soil microcosms. Because shrubland soil usually contained multiple species of nematode-trapping fungi, and especially A. oligospora, we quantified nematode suppression by combinations of A. oligospora and G. paucispora or M. eudermatum. Fungi were added in the form of fungal-colonized nematodes to pasteurized soil, and nematode suppression was measured by comparing nematode invasion of wax moth larvae. Suppression of H. hepialus tended to be less in mixed treatments with A. oligospora than in treatments with G. paucispora or M. eudermatum alone. Population densities of M. eudermatum and G. paucispora were less in the presence than in the absence of A. oligospora. In contrast, A. oligospora population density was unaffected or possibly enhanced by the other fungi.

Key Words:

• Heterorhabditis hepialus
• most probable number
• soil ecology