Elucidation of the evolution of reproductive traits of the host pest, sweet potato weevil, driven by symbiotic bacteria and its application to control technology.

2021 Fiscal Year Final Research Report

• Project/Area Number: 18K05667
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 39050:Insect science-related
• Research Institution: Obihiro University of Agriculture and Veterinary Medicine
• Principal Investigator: KUMANO Norikuni 帯広畜産大学, 環境農学研究部門, 准教授 (90621053)
• Co-Investigator(Kenkyū-buntansha): 菊池 義智 国立研究開発法人産業技術総合研究所, 生命工学領域, 主任研究員 (30571864) ; 日室 千尋 琉球大学, 農学部, 協力研究員 (60726016)
• Project Period (FY): 2018-04-01 – 2022-03-31
• Keywords: イモゾウムシ / 共生細菌 / 性淘汰 / 共進化 / 配偶行動

Outline of Final Research Achievements

The sweet potato weevil, Euscepes postfasciatus, depends on the symbiotic bacterium for the formation of the cuticle, which is necessary for the hardening of the exoskeleton and/or genitalia. These play important roles in the sexual selection by female and sperm transport and strongly suggest that the symbiont is directly involved in host sexual selection. In this study, we investigated the mating behavior of this weevil by manipulating the amount of symbiotic bacteria it possesses. We observed an increase in the number of male mounting behavior before copulation, an increase in the mating rate, and a shortening of the copulation duration in the treated individuals. In addition, the number of spines on male genitalia was reduced, and the number of the next generation was also reduced.

Free Research Field

行動生態学

Academic Significance and Societal Importance of the Research Achievements

サツマイモはイモゾウムシの被害を受けると，毒性のあるイポメアマロンなどを分泌する．この物質は強毒性であるため，サツマイモがゾウムシ類の被害を受けた場合，被害芋は家畜の餌にもならず，その経済的損失は極めて多い．現在のところ不妊虫放飼法による防除が沖縄県で行われているが，防除効果を向上させる新たな技術が必要とされている．本研究の成果は，蛹期の熱処理により，処理雄の交尾率の上昇することが明らかになった．寄主生物の性淘汰における共生細菌の役割はほとんど明らかになっておらず，今後の研究でその原因が解明されれば，不妊虫放飼法による防除効果を向上させる新規技術となる可能性がある．