Search Results (4)

The banana pseudostem weevil (BPW), Odoiporus longicollis (Oliver), is one of the most destructive pests of bananas that is seriously affecting the yield and quality of bananas. We isolated pathogens from banana pseudostem weevils in Xishuangbanna and Dongchuan, Yunnan, China, and explored their biological characteristics. The pathogenicity of the strains was verified through laboratory and greenhouse inoculation experiments. The results showed that four strains of fungi were identified and confirmed as Beauveria caledonica (Bc) via ITS-rDNA sequencing. Optimal in vitro culture conditions were found to be a photoperiod of 24 h light, 25 °C temperature, and 18 days on potato dextrose agar (PDA) medium with insect meal. Under these conditions, the Cs-1 strain achieved a colony diameter of 65.17 ± 0.74 mm and spore production of 1.24 × 10⁸ cfu/cm². The Cs-1 strain had the shortest lethal time (LT₅₀) of 9.36 days at an inoculum of 1.00 × 10⁹ cfu/mL, with a lethality of 86.67% after 20 days. The Cs-3 strain showed 77.78% lethality at 1.00 × 10⁸ cfu/mL after 20 days. Despite variations in virulence, lethality did not correlate with major cuticle-degrading enzymes. The Cs-3 strain demonstrated effective biocontrol in greenhouse tests. Banana plants suffered significant damage without Bc-treated BPW, while the treated plantlets thrived. The mortality rate reached 82.78% after 35 days. This study marks the first identification of these entomopathogenic fungi (EPF) in Yunnan, China, highlighting B. caledonica’s potential for biocontrol application. Full article

Cephalcia chuxiongica has caused significant damage to pine forests, becoming a major biological disaster that hinders the sustainable development of forestry in China. To investigate the efficacy of biological control measures, entomopathogenic fungi were isolated and purified from the larvae of Ce. chuxiongica that had succumbed to diseases. The pathogenic capacity of strains was assessed using bioassay methods, and their infection process was observed using scanning electron microscopy. ITS, LSU, and TEF analysis disclosed Clonostachys rogersoniana as the highly virulent strain responsible for the death of Ce. chuxiongica. The optimal medium for its mycelial growth and sporulation was found to be PPDA. In addition, the bioassay revealed that the median lethal time (LT₅₀) for Ce. chuxiongica was 24.34 h and median lethal concentration (LC₅₀) was 2.35 × 10⁵ conidia/mL, indicating that C. rogersoniana possesses potent virulence and demonstrates rapid pathogenicity. Furthermore, scanning electron microscopy demonstrated that C. rogersoniana initially entered the body of Ce. chuxiongica through the spiracle and progressively made its way into the body wall, resulting in the insect’s death. The mode of infection for C. rogersoniana is exceedingly rare. As a consequence, the results of this study can serve as a reference for the management of chewing insects, such as Ce. chuxiongica. Full article

Biological control agents are a promising substitute for chemical pesticides in agricultural pest management. In this study, Penicillium sp. with high pathogenicity to the agricultural pests oriental leafworm moth (Spodoptera litura) and diamondback moth (Plutella xylostella) were isolated from naturally infected insects and grown on different agricultural residues as an inexpensive substrate for their sporulation. Ten strains of Penicillium (P.01~P.10) were identified as P. citrinum based on morphological features and molecular studies, with sequence analysis using an internal transcribed spacer region. Different fungal isolates exhibited a varying degree of pathogenicity against S. litura and Pl. xylostella, and strains P.04 and P.09 showed the highest pathogenicity to S. litura, with a mortality rate of 92.13% after 7 days of treatments, while strain P.06 resulted in the highest mortality of Pl. xylostella (100%) after 6 days of treatment. Moreover, among ten isolates infected with both S. litura and P. xylostella, P.06 showed potential virulence against S. litura and Pl. xylostella, with lethal time for 50% mortality (LT₅₀) values of 4.5 days and 3.0 days, respectively. The ten isolates showed higher virulence to Pl. xylostella than to S. litura. The agro-industrial-based medium showed efficiency for the cultivation of isolates for sporulation on an industrial scale, suggesting that the newly isolated P. citrinum is a potential biological control agent for controlling insect pests and could be further developed for microbial pesticide production. Full article

Diamondback moth (DBM) is an important horticultural pest worldwide as the larvae of these moths feed on the leaves of cruciferous vegetables. As DBM has developed resistance to more than 100 classes of synthetic insecticides, new biological control options are urgently required. Beauveria species are entomopathogenic fungi recognized as the most important fungal genus for controlling a wide range of agricultural, forestry, and veterinary arthropod pests. Previous research, aimed at developing new Beauveria-based biopesticides for DBM, has focused on screening single isolates of Beauveria bassiana. However, these fungal isolates have individual requirements, which may limit their effectiveness in some environments. This current study separately assessed 14 Beauveria isolates, from a range of habitats and aligned to four different species (Beauveria bassiana, B. caledonica, B. malawiensis, and B. pseudobassiana), to determine the most effective isolate for the control of DBM. Further assays then assessed whether selected combinations of these fungal isolates could increase the overall efficacy against DBM. Six Beauveria isolates (three B. bassiana and three B. pseudobassiana) achieved high DBM mortality at a low application rate with the first documented report of B. pseudobassiana able to kill 100% of DBM larvae. Further research determined that applications of low-virulent Beauveria isolates improved the control of DBM compared to mixtures containing high-virulent isolates. This novel approach increased the DBM pest mortality and shortened the time to kill. Full article