Viability and Predatory Capacity of Duddingtonia flagrans After Fourteen Years of Storage in Alginate Pellets

Nematophagous fungi are important biological control agents that naturally reduce nematode populations through specialized predatory mechanisms. This study evaluated the viability and predatory capacity of the nematophagous fungus Duddingtonia flagrans (AC001) after fourteen years of refrigerated storage in sodium alginate pellets. Fungal viability was assessed by reactivating the pellets on Corn Meal Agar and Potato Dextrose Agar, with subsequent monitoring of mycelial growth and morphological confirmation by light microscopy. The predatory capacity was determined by means of in vitro assays using Panagrellus redivivus as a model organism. Plates previously colonized by the fungus received approximately 400 nematodes and were compared with fungus-free controls. Predatory activity was evaluated daily for five days by counting live nematodes in random microscopic fields. Final recovery of viable nematodes was performed using a modified Baermann technique. The data were analyzed using Student’s t-test (p < 0.05). Isolate AC001 exhibited successful reactivation, preserved morphological characteristics, and sustained high predatory activity, resulting in reductions in nematode populations ranging from 91% on the first day to 95% on subsequent days, with a final reduction of 67% in nematode recovery. These findings demonstrate that sodium alginate encapsulation combined with refrigeration enables the exceptionally long-term preservation of functional and predatory attributes of nematophagous fungi, supporting its applicability in biological control strategies.