Novel isolate of Cladosporium subuliforme and its potential to control Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae)

Abstract

Background: Citrus fruits are economically and nutritionally important but have been severely affected by Huanglongbing disease (HLB), its natural spread is mainly by the Asian Citrus Psyllid,Diaphorina citri Kuwayama (Hemiptera: Liviidae). Chemicals are often used to control this pest, but this is not sustainable. Meanwhile, there are few environmentally friendly bioinsecticides to control D. citri in China. Results: In this study, an entomofungal pathogen wz-1 was isolated from a D. citri carcass in the field, which resulted in a cumulative mortality rate of 75.27% in adult D. citri 7 days after inoculation of the spore suspension. It was identified as Cladosporium subuliforme based on morphological analysis as well as sequence analysis of several molecular markers (Internal Transcribed Spacers, Translation Elongation Factor 1-α and Actin). Remarkably, the lethality rate of adult D. citri reached 53.13%, 48 h after treatment with the aqueous phase extracts of wz-1. Hydroxyquinoline and phytosphingosine in the extracts were identified as potentially active metabolites using LC–MS. Conclusions: The entomopathogenicity and bioinsecticidal potential of C. subuliforme were previously unknown. Obtained results showed that both spores and extracts of wz-1 can effectively kill adult D. citri, providing an available fungal resource and a theoretical basis for biocontrol of the HLB insect vector D. citri.