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 experiments mimic 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.

长期以来， Melittobia黄蜂令人费解的性别比例行为一直是性别分配领域最大的问题之一。实验室实验发现，与理论预测和许多其他生物体的行为相反，当更多雌性在一块土地上产卵时，雌性Melittobia并不会产生更少的雌性后代性别比例。我们通过证明在自然界中，雌性澳洲花蜂具有复杂的性别比例行为来解决这个难题，其中它们的策略还取决于它们是否已经从它们出现的地方分散开来。当雌性尚未分散时，它们会与近亲一起产卵，这使得即使有多个雌性，当地的交配竞争也很激烈，因此，它们被选择以产生始终偏向雌性的性别比例。实验室实验模拟了这些条件。相反，当雌性分散时，它们会与非亲属互动，从而根据产卵的雌性数量调整其性别比例。因此，雌性似乎将分散状态作为相关性的间接线索，以及是否应该根据在该斑块上产卵的雌性数量来调整其性别比例。