European Journal of Epidemiology

, Volume 13, Issue 1, pp 19–23 | Cite as

Occurrence of high ratio of males after introduction of minocycline in a colony of leptotrombidium fletcheri infected with orientia tsutsugamushi

  • Mamoru Takahashi
  • Hiroshi Urakami
  • Yoshiya Yoshida
  • Yumiko Furuya
  • Hitoko Misumi
  • Eitaro Hori
  • Akiyoshi Kawamura
  • Hiroshi Tanaka


In colonies of Leptotrombidium fletcheri mites infected with Orientia tsutsugamushi (Ot), the agent of scrub typhus, males rarely appear. In the present study, the development of a high ratio of males was observed after introduction of minocycline (MC). A high dose of MC was injected subcutaneously into a mouse, and by feeding unfed larvae from an infected mite colony on this mouse, the Ot in the mites were successfully killed. Of a total of 130 unfed larvae attached to the mouse, 29 developed into females; of these, 9 laid an average of 112.4 eggs/female. Unfed larvae in the succeeding generations were attached to untreated mice. All adults in the P and F1 generations were females, and males started to appear at the F2 generation. The ratio of males to females was 332:7, 108:13, 263:61 and 71:9 at the F2, F3, F4 and F5 generations, respectively. These data suggest that Ot in the ovary or gonad may suppress the development of males.

Infected colony Leptotrombidium fletcheri Minocycline Orientia tsutsugamushi Sex ratio 


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Copyright information

© Kluwer Academic Publishers 1997

Authors and Affiliations

  • Mamoru Takahashi
    • 1
    • 2
  • Hiroshi Urakami
    • 3
  • Yoshiya Yoshida
    • 4
  • Yumiko Furuya
    • 4
  • Hitoko Misumi
    • 5
  • Eitaro Hori
    • 6
  • Akiyoshi Kawamura
    • 7
  • Hiroshi Tanaka
    • 7
  1. 1.Kawagoe Agricultural Senior High SchoolKosenba-machi, Kawagoe City, SaitamaJapan
  2. 2.Department of Medical ZoologySaitama Medical SchoolMoroyama-machi, SaitamaJapan
  3. 3.Department of MicrobiologyNiigata College of PharmacyKamishin'ei-cho, NiigataJapan
  4. 4.Division of VirologyKanagawa Prefectural Public Health LaboratoryAsahi-ku, Yokohama, KanagawaJapan
  5. 5.Laboratory of ChemistryKagawa Nutrition University, Komagome, Toshima-Ku, TokyoJapan
  6. 6.Department of Medical ZoologySaitama Medical SchoolMoroyama-machi, SaitamaJapan
  7. 7.Institute of Medical ScienceThe University of TokyoShirokanedai Minato-ku, TokyoJapan

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