Effects of physioligical stresses and soil fungistasis on survival and infection of entomopathogenic fungi in soil

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K23677
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0602:Agricultural and environmental biology and related fields
• Research Institution: Kyushu University
• Principal Investigator: Nishi Oumi 九州大学, 農学研究院, 助教 (30747879)
• Project Period (FY): 2019-08-30 – 2021-03-31
• Keywords: 昆虫寄生菌 / 微生物的防除 / 土壌定着能力 / 紫外線耐性 / 高温耐性 / 土壌静菌作用 / アザミウマ

Outline of Final Research Achievements

Entomopathogenic fungus Metarhizium sp. SMZ2000 strain had the highest control efficacy against western flower thrips and persistence among tested fungal strains including Beauveria sp. GHA strain when it was introduced into soil surface. As a result of evaluation of physiological characters possibly related to the high control efficacy and persistence in soil, SMZ2000 was almost equivalent to GHA in heat and UV stress resilience, however, SMZ2000 was higher in virulence against pupal stage of thrips and lower in germination capacity under soil fungistasis. Regarding pathogenicity, second pupa is more susceptible to fungal infection than first pupa. In addition, infection in pupal stage caused deformation of wings in adult.

Free Research Field

昆虫病理学

Academic Significance and Societal Importance of the Research Achievements

昆虫寄生菌を土壌生息害虫の防除に効果的に利用するためには、土壌環境が昆虫寄生菌の生残や感染に及ぼす影響の理解が重要である。本研究では施設栽培作物の重要害虫であり蛹期を土壌表層で生活するミカンキイロアザミウマを対象として、土壌環境の昆虫寄生菌への影響を評価し、土壌中での発芽能力が低い菌株でも高い防除効果と土壌定着能力を示し得ることを明らかにした。また、アザミウマ蛹に対する病原性に関して、第1蛹よりも第2蛹の方が感受性が高いことや、蛹期の感染により羽化成虫において翅形成異常が生じるなど新規の重要な知見が得られた。本成果は昆虫寄生菌の土壌導入による効果的なアザミウマ防除法の開発に資する。