Screening of Insecticidal and Antifungal Activities of the Culturable Fungi Isolated from the Intertidal Zones of Qingdao, China

Numerous studies focused on drug discovery perspective have proved the great potential for exploration of marine-derived fungi to seek bioactive chemicals. Yet, marine-derived fungi are less explored compared to their terrestrial counterparts. Here, 181 fungal strains (134 species) isolated from marine algae and sediment in Chinese intertidal zones were screened to reveal bioactivities using brine shrimp, green peach aphid and plant pathogens as targets. Fermentation supernatants of 85 fungal strains exhibited a high lethality (>70%) of brine shrimp at 24 h, and 14 strains appeared to be acute-toxic as featured by more than 75% mortality at 4 h, indicating efficient insecticidal bioactivity. The crude extracts of 34 strains displayed high toxicity to green peach aphid with more than 70% of mortality at 48 h. For the plant pathogens tested, the inhibitory rates of eight fungal strains affiliated with Alternaria (AS3, AS4), Amphichorda (AS7), Aspergillus (AS14), Chaetomium (AS21), Penicillium (AS46), Purpureocillium (AS55) and Trichoderma (AS67) were equal or higher than that of the positive Prochloraz, and five of them (AS7, AS14, AS21, AS55, AS67) were also strongly toxic to brine shrimp or aphid. Our findings indicate broad potential for exploration of marine-derived fungi as candidate resources to pursue bioactive compounds in controlling agricultural pests and pathogens.