毛虫の摂食行動を促進するキノコの働きを解明(Fungus Drives Increased Feeding in Caterpillars to Favor Its Own Fruiting)

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2025-06-30 中国科学院(CAS)

中国科学院植物分子科学卓越革新センターなどの研究により、冬虫夏草の一種「Cordyceps militaris(C. militaris)」がカイコ幼虫の摂食行動を促進することで、より栄養価の高い蛹を形成させ、自らの子実体(果実体)形成を有利にすることが判明しました。感染後、幼虫の摂食量と体重が増加し、脳内で食欲促進ペプチド「HemaP」が継続的に活性化。さらに、C. militarisは昆虫由来と推定される酵素「CmTreH1(トレハラーゼ)」を用い、昆虫体内の主要血糖であるトレハロースを分解し、空腹状態を誘導。これが摂食行動の増加に繋がっていました。本研究は、真菌による宿主行動の遺伝子レベルでの操作(拡張表現型)の新たな例を示し、冬虫夏草の安価な大量生産にも寄与する可能性があります。

<関連情報>

真菌病原体は宿主様トレハラーゼを用いて毛虫の摂食と体重増加を促進する Fungal pathogen promotes caterpillar feeding and weight gain using a host-like trehalase

Peiqing Zhao ∙ Jianfeng Lin ∙ Dehong Yang ∙ … ∙ Xuewen Wang ∙ Yongping Huang ∙ Chengshu Wang
Current Biology  Published:June 27, 2025
DOI:https://doi.org/10.1016/j.cub.2025.06.002

Graphical abstract

毛虫の摂食行動を促進するキノコの働きを解明(Fungus Drives Increased Feeding in Caterpillars to Favor Its Own Fruiting)

Highlights

  • Cordyceps militaris infection of silkworms promotes feeding and weight gain
  • Fungal infection triggers starvation-like responses in silkworms
  • C. militaris encodes an insect-like trehalase that reduces hemolymph trehalose
  • Infection induces the orexigenic peptide HemaP to promote caterpillar feeding

Summary

Parasite-mediated extended phenotypes in hosts are of particular interest in biology. However, few parasite genes have been characterized for their selfish role in altering host behaviors to benefit parasite transmission or reproduction. The entomopathogenic fungus Cordyceps militaris infects caterpillar larvae without killing them until after pupation. Here, we report that fungal infection of silkworm larvae induces increased feeding and weight gain, which is manifested by starvation-like responses, including the constant upregulation of the orexigenic peptide HemaP and a sharp reduction in hemolymph trehalose levels. Engineered fungal strains overexpressing HemaP further enhance silkworms’ excessive feeding and weight gain. Disruption of HemaP in silkworms reduced trehalose production and pupal weight, thereby decreasing fungal fruiting body formation on mutant pupae. Consistent with the depletion of blood sugars, an insect-like trehalase gene was upregulated in fungal cells growing within insect body cavities, and deleting this gene in C. militaris abolished fungal ability to promote weight gain in silkworms after infection. Our data shed light on a previously unsuspected extended phenotype: fungal promotion of insect feeding through the function of a host-like gene, ultimately benefiting fungal reproduction.

生物化学工学
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