A solution to a sex ratio puzzle in Melittobia wasps

Jun Abe, Ryosuke Iritani, Koji Tsuchida, Yoshitaka Kamimura, Stuart A. West

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


The puzzling sex ratio behavior of Melittobia wasps has long posed one of the greatest questions in the field of sex allocation. Laboratory experiments have found that, in contrast to the predictions of theory and the behavior of numerous other organisms, Melittobia females do not produce fewer female-biased offspring sex ratios when more females lay eggs on a patch. We solve this puzzle by showing that, in nature, females of Melittobia australica have a sophisticated sex ratio behavior, in which their strategy also depends on whether they have dispersed from the patch where they emerged. When females have not dispersed, they lay eggs with close relatives, which keeps local mate competition high even with multiple females, and therefore, they are selected to produce consistently female-biased sex ratios. Laboratory experimentsmimic these conditions. In contrast, when females disperse, they interact with nonrelatives, and thus adjust their sex ratio depending on the number of females laying eggs. Consequently, females appear to use dispersal status as an indirect cue of relatedness and whether they should adjust their sex ratio in response to the number of females laying eggs on the patch.

Original languageEnglish
Article numbere2024656118
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number20
Publication statusPublished - 2021 May 18


  • Dispersal
  • Kin selection
  • Local mate competition
  • Relatedness
  • Sex allocation

ASJC Scopus subject areas

  • General


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