2018 Fiscal Year Final Research Report

Qualitative and quantitative analysis of infection and metabolic regulation of Farinocystis sp. in the host weevil, Euscepes postfasciatus

Research Project

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Project/Area Number	16K08100
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Research Field	Insect science
Research Institution	Kyushu University
Principal Investigator	Chisa Yasunaga-Aoki 九州大学, 農学研究院, 教授 (20264103)
Research Collaborator	FUKUI shota MATSUYAMA takashi CASSAL maximiano correa
Project Period (FY)	2016-04-01 – 2019-03-31
Keywords	Farinocystis sp. / Euscepes postfasciatus / オーシスト人工脱嚢法 / スポロゾイト単離 / 感染培養系 / パルスNMR法
Outline of Final Research Achievements	A Farinocystis neogregarine parasite was isolated from mass-reared colonies of the West Indian sweet potato weevil, Euscepes postfasciatus, at the facility of Okinawa Prefectural Plant Protection Center (OPPPC) in 2004. First, in order to evaluate the virulence of Farinocystis sp. against the host both qualitatively and quantitatively, artificial excystation of the oocysts was investigated. It revealed that a pretreatment with hexane was most effective for the oocyst excystation. Then, in order to evaluate a horizontal transmission through the oocysts, bioassays against various insect pests of sweet potato were conducted as well as host intestinal factors related to the oocyst excystation were investigated. Several proteases such as serine protease were involved in the oocyst excystation. In the pulse NMR experiment, metabolic changes and differences were detected between infected and non-infected host individuals.
Free Research Field	昆虫病理学
Academic Significance and Societal Importance of the Research Achievements	本研究は、侵入害虫且つ難防除害虫のイモゾウムシから初めて分離された原虫を対象とした。この原虫病は達成間近の根絶防除事業を阻む深刻な原因となっており、本研究から得られた成果はイモゾウムシ根絶防除に寄与できるものである。また、本原虫の宿主はイモゾウムシに限られており、極めてユニークな生態をもって宿主個体・個体群での感染を維持している可能性が高い。そのため、本研究で明らかとなった原虫の生物学的諸性状は、新たなグレガリナ原虫特性の発見へと繋がるものである。また、イモゾウムシの代謝解析により明らかとなった原虫感染が宿主昆虫に与える影響の一端は、昆虫病理学に大いに貢献するものである。