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Scientia Silvae Sinicae ›› 2018, Vol. 54 ›› Issue (6): 100-108.doi: 10.11707/j.1001-7488.20180612

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Effects of Three Different Metarhizium Strains on Virulence and Protective Enzymes Activities of Melanotus cribricollis larvae

Ye Bihuan1,2, Zhang Yabo1, Shu Jinping1, Wu Hong1, Wang Haojie1   

  1. 1. Research Institute of Subtropical Forestry, CAF Hangzhou 311400;
    2. Zhejiang Academy of Forestry Hangzhou 310023
  • Received:2016-12-06 Revised:2017-02-16 Online:2018-06-25 Published:2018-07-02

Abstract: [Objective] The bamboo wireworm (Melanotus cribricollis larvae) is one of the most rampant forest pests causing serious damage to bamboo shoots in southern China. It is hard to monitor and control this pest till now. Metarhizium spp. can be used for biocontrol of the wireworm. The purpose of this study is to screen high pathogenicity Metarhizium strain and explore the immune response of protective enzyme system in the wireworm after the fungal infection.[Method] The pathogenicity tests by applying three Metarhizium strains against the pest larvae with different spore concentrations were conducted. The dynamic activity changes of three protective enzymes in the host larvae, i.e. superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), were also determined during different infect periods.[Result] Results showed that all the three isolates possessed lethal property were able to infest M. cirbricollis larvae, among which M. pingshaense WP08 strain was the best, M. anisopliae WTKH strain was the second and M. acridum strain the last. The pathogenicity was enhanced with the increased spore concentration. With 108 spore·g-1 DW soil, M. pingshaense WP08 strain exhibited the highest toxicity and all of the tested larvae died in 16 d, but M. pingshaense WP08 strain with 107 spore·g-1 DW soil had no significant pathogenicity. There was difference in the dynamic change trends of three protective enzyme activities. There was no significant difference in the SOD activity. However, the CAT activity firstly down-regulated, then up-regulated and declined again subsequently, and the POD activity showed similar fluctuation trend to the CAT activity, but there was no significant difference at the late stage (5-7 d).[Conclusion] The present study indicated that M. pingshaense WP08 strain was the best entomopathogenic fungus to infect M. cribricollis larvae compared with other two strains. Therefore, the strain could be first selected as a biocontrol agent for control of the wireworm in bamboo forests. The fungal infection influenced activities of the three protective enzymes, especially to CAT activity.

Key words: larvae of Melanotus cribricollis, Metarhizium spp., pathogenicity, protective enzymes

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