Numerical responses of the nematophagous fungi Hirsutella rhossiliensis, Monacrosporium cionopagum, and M. ellipsosporum.

TLDR: Overall, the two trapping fungi appear to have greater potential than does H. rhossiliensis for biological control of certain plant-parasitic nema?

Abstract: A soil microcosm experiment was conduct? ed to measure the effect of nematode population den? sity on suppression of nematodes by Hirsutella rhos- siliensis, Monacrosporium cionopagum, and M. ellipsos- porum. These fungi use adhesive conidia, branches, and knobs, respectively, to parasitize nematodes, and were added to soil in the form of pelletized hyphae. Nematode population density was controlled by add? ing small to large numbers of the insect-parasitic nem? atode Steinernema glaseri. Suppression was determined by adding a fixed number of the root-knot nematode Meloidogyne javanica and measuring the number (rel? ative to a control without fungi) that penetrated the roots of a cabbage seedling planted in each microcosm. Suppression by M. ellipsosporum and H. rhossiliensis was positively related to S. glaseri density, suggesting that M. ellipsosporum, like H. rhossiliensis, depends on par? asitism rather than on saprophytism. The response of M. cionopagum to nematode density was inconsistent. In a second experiment, the change in suppression of M. javanica over time was measured in soil containing few nematodes. Suppression by M. cionopagum in? creased rapidly to nearly 100% within 10 days follow? ing addition of fungal inoculum to soil and then de? clined sharply. Suppression by M. ellipsosporum in? creased gradually throughout the study and was nearly 100% at day 120. Suppression by H. rhossiliensis in? creased to only about 50% by day 20 and then declined gradually. Overall, the two trapping fungi appear to have greater potential than does H. rhossiliensis for biological control of certain plant-parasitic nema? todes.