The Evaluation of Egg-Parasitic Fungi Paraboeremia taiwanensis and Samsoniella sp. for the Biological Control of Meloidogyne enterolobii on Chinese Cabbage

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 taiwanensisandSamsoniellasp., were evaluated againstM. enterolobiiand compared to the known biological control agentsHyalorbilia oviparasiticastrain DoUCR50 andPurpureocillium lilacinumstrain 251 (PL251). BothP. taiwanensisandSamsoniellasp. 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% byP. taiwanensisand 47.50% forSamsoniellasp., 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 againstM. enterolobiiwas further confirmed. For all fungi examined in this study, fungal hyphae were seen apparently penetrating intoM. enterolobiieggs 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 forP. taiwanensis,Samsoniellasp.,H. oviparasiticaDoUCR50, andP. lilacinumPL251. It further enlightens the application potential of nematophagous fungi as biocontrol agents against plant-parasitic nematodes in vegetable crop management.