Abstract:

Objective: The aim of this study was to develop a new method to transmit entomopathogenic fungi by a biological vector, Pyemotes moseri, to biologically control the long-horned beetle, Anoplophora glabripennis, efficiently. Method: Pyemotes combined with entomopathogenic fungi spores was used as an approach to spread the entomopathogenic fungi spores into the larval galleries of the long-horned beetle for effective infection of the larvae. An outdoor simulated control test was carried out by using one meter damaged poplar trunks with the trunk base planted in soil and covered with mesh net. Each treatment was triple replicates and each replicate was made of ten damaged poplar trunks. Four treatment groups were set up, and the release unit in four treatments respectively included Pyemotes and Beauveria bassiana, Pyemotes and Metarhizium anisopliae, B. bassiana and M. anisopliae, Pyemotes. Blank control was sterile without mites in the release unit. The number of frass holes and emergence holes of long-horned beetle damaged poplar trunks was counted before experiments and re-counted after one month of treatments. After one month, the poplar trunks was split to check whether the larvae of A. glabripennis were infected by the entomopathogenic fungi. Field efficacy tests were conducted in Jiuquan city of Gansu province in August 2021. To fix the release unit on central poplar which was damaged by A. glabripennis in Shiquanhe Bridge forest maintenance region. After one month, the field control efficacy was investigated to confirm the effective control diameter of each release unit. Result: The results of outdoor simulated control test showed that the proportion of frass holes in Pyemotes and B. bassiana, Pyemotes and M. anisopliae respectively reduced 77.0 % and 83.1 % compared to blank control, and there was no new emergence hole. The larvae mortality of Pyemotes and B. bassiana was 77.5 %, Pyemotes and M. anisopliae was 85.0 %. The larvae were infected by entomopathogenic fungi in split trunks from treatment of Pyemotes and B. bassiana, Pyemotes and M. anisopliae, which was confirmed the infection was caused by the entomopathens used in the tests. Field efficacy tests in Jiuquan indicated that effective control diameter of each release unit was 10.0 m where frass holes reduced more tahn 50%. Conclusion: The vector, Pyemotes moseri can successfully transmit entomopathogenic fungi spores into the larval galleries of long-horned beetle and cause effective infection to larvae with a final mortality of 80%. Each release unit of P. moseri with fungi spores transmission diameter is 10.0 m. This vector transmission biocontrol for long-horned beetle is a firstly reported new method that the insecticidal entomopathogens are transmitted by the tiny vector P. moseri, and cause an effective infection to larvae with high mortality. This vector transmission biocontrol technique has a potential to be developed as an effective, easy operation and environmentally friendly new technique to control long-horned beetle.

Key words: Anoplophora glabripennis, biological control, bio-vector, Pyemotes moseri, entomopathogenic fungi