Anthracnose is a destructive postharvest disease of mango fruit, especially after ripening. The application of antagonistic Bacillus spp. strains is one of many promising control strategies. B. amyloliquefaciens (PMB04) exhibits strong antagonistic activity against anthracnose in strawberry fruit, yet has not been explored for anthracnose control in mango fruit. Among seven tested rhizobacterial strains, PMB04 exhibited the strongest inhibition against Colletotrichum gloeosporioides (Cg) growth. PMB04 demonstrated better inhibitory activity against Cg mycelial growth than the fungicides pyraclostrobin and difenoconazole. A PMB04 fermentation broth (PMB04FB) was prepared and tested, and showed superior efficacy in the reduction of anthracnose disease severity in mangoes compared to a PMB04 suspension, difenoconazole, or pyraclostrobin. We further found PMB04FB increased the mortality ratio of Cg conidia. Our study demonstrates that treatment with PMB04FB is an effective control method for anthracnose in mango and represents a promising strategy for postharvest mango processing.

Sweet pepper is an important vegetable in the world. Bacterial leaf spot, caused by the pathogen Xanthomonas perforans, is a limiting factor that significantly reduces the quality and yield of sweet peppers. The use of chemical fungicides is currently the main disease-control method for bacterial leaf spot disease. It is important to develop an eco-friendly biocontrol method by using antagonistic microorganisms. Bacillus amyloliquefaciens PMB04 has strong antagonistic effects against pathogens and can inhibit the occurrence of diseases. B. amyloliquefaciens PMB04 has the potential for the development of a disease-control product. Primarily, PMB04 contained a strong inhibitory effect against all isolated X. perforans strains. In the inoculation assay, the severity of bacterial leaf spot disease on sweet peppers was reduced by PMB04 bacterial suspensions. To increase the convenience of field applications in future prospects, the development of the PMB04 fermentation liquid was carried out using different ratios of brown sugar and yeast extract in a 30 L fermentation tank. The results exhibited that the fermentation liquid of the 3-1 and 2-1 formulas obtained the highest bacterial population in a 30 L fermentation tank. The fermentation liquid of the 0.5-0.5 formula was the most stable formula for two different conditions in terms of a consistent bacterial population and sporulation. In addition, the 200-fold dilution of the 3-1 and 0.5-0.5 fermentation liquids revealed the best control efficacy on bacterial leaf spot disease of sweet peppers. Additionally, the results of the 0.5-0.5 fermentation liquid (PMB4FL) with different dilution concentrations also demonstrated that the 200- and 500-fold dilutions had the best control efficacy. To understand the effect of commonly used copper-containing fungicides on sweet peppers on the application of microbial agent PMB4FL, the effects of copper hydroxide and tribasic copper sulfate on the growth of X. perforans strains and B. amyloliquefaciens PMB04 were assayed. The results exhibited that the above two fungicides did not have any inhibitory effect on the growth of PMB04 but had a strong inhibitory effect on the X. perforans strain. In the follow-up control experiment, the treatment of copper hydroxide had no synergistic effect with PMB4FL to control bacterial leaf spot disease. We concluded that the use of the PMB4FL fermentation liquid alone on the leaves could effectively control the occurrence of bacterial leaf spots in sweet pepper crops.

Sweet pepper is an important vegetable in the world. Bacterial leaf spot caused by the pathogen Xanthomonas perforans, is a limiting factor that significantly reduces the quality and yield of sweet pepper To control this disease, the use of chemical fungicides is currently the main disease control method. Thus, we want to develop an alternative method by using antagonistic microorganisms. Under this demand, Bacillus amyloliquefaciens PMB04 has strong antagonistic effects against pathogens and can inhibit the occurrence of diseases. B. amyloliquefaciens PMB04 has the potential for the development of a disease control product. Primarily, PMB04 revealed to contain a strong inhibitory effect against all isolated X. perforans strains. In the inoculation assay, the severity of bacterial spot disease on sweet peppers was reduced by PMB04 bacterial suspensions. To increase the convenience of field application for future prospects, the development of PMB04 fermentation liquid was carried out with different ratios of brown sugar and yeast extract in a 30-liter fermentation tank subsequently. Results exhibited that the fermentation liquid of 3-1 formula obtained the highest bacterial population in a 30-liter fermentation tank. The fermentation liquid of 0.5-0.5 formula was the most stable formula under two different conditions in terms of consistent bacterial population and sporulation. In addition, the 200-fold dilution of 3-1 and 0.5-0.5 fermentation liquids revealed best control efficacy on bacterial leaf spot of sweet pepper. Additionally, the results of the 0.5-0.5 fermentation liquid (PMB4FL) with different dilution concentrations also showed that the 200- and 500-fold dilutions had the best control efficacy. To understand the effect of commonly used copper-containing fungicides on sweet peppers on the application of microbial agent PMB4FL, the effects of copper hydroxide and tribasic copper sulfate on the growth of X. perforans strains and B. amyloliquefaciens PMB04 were assayed. The results exhibited that the above two fungicides did not have any inhibitory effect on the growth of PMB04, but had a strong inhibitory effect on the X. perforans strain. In the follow-up control experiment, the treatment of copper hydroxide had no synergistic effect with PMB4FL to control bacterial leaf spot. We concluded that the use of PMB4FL fermentation liquid alone on the leaves can effectively control the occurrence of bacterial leaf spot in sweet pepper crops.

Bursaphelenchus rainulfi is a pine-associated, non-pathogenic nematode that serves as a motile comparative species for evaluating nematophagous fungi. We investigated the in vitro biocontrol activity of Purpureocillium takamizusanense strain PMEPF27, originally isolated from insect cadavers in Taiwan, against mixed motile stages of B. rainulfi. Identity of the fungus was confirmed by morphology and ITS/EF-1α sequencing. Nematodes were exposed in liquid suspension to PMEPF27 conidia, with sterile water as the negative control and fluopyram as the positive control. Mortality was monitored over 7 days, and scanning electron microscopy was used to observe fungus–nematode interactions. PMEPF27 caused significantly higher mortality than the water control, reaching ~80% by day 7, and showed surface disruption of nematode cuticles, although no direct spore penetration was observed. These findings expand the nematophagous profile of P. takamizusanense beyond egg and sedentary stages, validate B. rainulfi as a motile comparative species in pine-nematode bioassays, and highlight PMEPF27 as a promising candidate for biocontrol development.

Cylas formicarius (Fabricius) is a major pest of sweet potato in Taiwan, where no microbial control agents are currently available. This study aimed to identify Beauveria bassiana strains with both high virulence and high spore productivity using a rice-based solid-state fermentation (SSF) system. Eleven field isolates were characterized using morphological traits and multilocus sequence analyses (Bloc, RPB1, RPB2, and TEF). Laboratory assays compared conidial production on 1/2 potato dextrose agar (PDA) and rice substrates and evaluated pathogenicity against adult C. formicarius by estimating median lethal time (LT₅₀) and the onset of mortality (t₀) based on cumulative mortality data. Substantial variation was observed among isolates in growth performance, sporulation, and virulence. Strain TyEf0054 consistently exhibited high pathogenicity, causing more than 80% mortality with conidia produced from both 1/2 PDA and rice, and showed rapid killing activity, with LT₅₀ values of approximately 5.5–5.9 days and t₀ values ranging from 3.55 to 3.99 days. In contrast, some strains exhibited high sporulation and virulence on 1/2 PDA but failed to produce conidia or showed severe clumping during rice-based solid-state fermentation, indicating poor suitability for large-scale production. These results demonstrate that high laboratory virulence alone is insufficient for strain selection and highlight the importance of integrating killing speed, final mortality, and SSF compatibility as joint selection criteria. Overall, TyEf0054 represents a promising locally adapted candidate for the development of commercial mycoinsecticides for sustainable management of sweet potato weevil in Taiwan.