UC Riverside

Meloidogyne enterolobii, an aggressive plant-parasitic nematode, has been causing great yield loss worldwide in recent years. With no resistant Chinese cabbage cultivar available currently, a biological control strategy is needed to offer an eco-friendly option for sustainable farming. In this study, the nematode suppression efficacy of two newly isolated fungi, Paraboeremia taiwanensis and Samsoniella sp., were evaluated against M. enterolobii and compared to the known biological control agents Hyalorbilia oviparasitica strain DoUCR50 and Purpureocillium lilacinum strain 251 (PL251). Both P. taiwanensis and Samsoniella sp. reduced 29%-63% disease severity as effectively as the commercial product PL251 on Chinese cabbage in greenhouse trails. The in vitro egg infection rate was 47.83% by P. taiwanensis and 47.50% for Samsoniella sp., respectively. A special protocol for scanning electron microscope observation of the fungi-infected nematodes was established in this study, and the egg parasitism of the four fungi against M. enterolobii was further confirmed. For all fungi examined in this study, fungal hyphae were seen apparently penetrating into M. enterolobii eggs without destructive damage of the overall outer eggshell and the hyphae continued to grow within eggs after 6 days of infection. The results of this study imply a similar egg-parasitism mechanism for P. taiwanensis, Samsoniella sp., H. oviparasitica DoUCR50, and P. lilacinum PL251. It further enlightens the application potential of nematophagous fungi as biocontrol agents against plant-parasitic nematodes in vegetable crop management.