Haplo-diploid sex determination in the parasitoid wasp, Nasonia vitripennis (Walker), allows females to adjust their brood sex ratios. Females influence whether ova are fertilized, producing diploid females, or remain unfertilized, producing haploid males. Females appear to adjust their brood sex ratios to minimize ‘local mate competition,’ i.e., competition among sons for mates. Because mating occurs between siblings, females may optimize mating opportunities for their offspring by producing only enough sons to inseminate daughters when ovipositing alone, and producing more sons when superparasitism is likely. Although widely accepted, this hypothesis makes no assumptions about gamete limitation in either sex. Because sperm are used to produce daughters, repeated oviposition could reduce sperm supplies, causing females to produce more sons. In contrast, if egg-limited females produce smaller broods, they might use fewer sperm, making sperm limitation less likely. To investigate whether repeated oviposition and female fertility influence gamete limitation within females, we created two treatments of six mated female wasps, which each received a series of six hosts at intervals of 24 or 48 h. All females produced at least one mixed-sex brood (63 total broods; 3,696 offspring). As expected, if females became sperm-limited, in both treatments, brood sex ratios became increasingly male-biased with increasing host number. Interhost interval did not affect brood size, total offspring number, or sex ratio, indicating females did not become egg limited. Our results support earlier studies showing sperm depletion affects sex allocation in N. vitripennis¸ and could limit adaptive sex ratio manipulation in these parasitoid wasps.

中文翻译：

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精子限制在黄蜂 Nasonia vitripennis（膜翅目：翼翅目）中产生雄性偏向后代性别比

寄生蜂 Nasonia vitripennis (Walker) 中的单倍体二倍体性别决定允许雌性调整其育雏性别比例。雌性影响卵子是受精，产生二倍体雌性，还是保持未受精，产生单倍体雄性。雌性似乎会调整她们的育雏性别比例，以尽量减少“本地配偶竞争”，即儿子之间争夺配偶的竞争。因为交配发生在兄弟姐妹之间，雌性可以通过在单独排卵时只生产足够多的儿子来为女儿授精，并在可能存在超寄生时生产更多的儿子来优化后代的交配机会。尽管被广泛接受，但这一假设并未对任何性别的配子限制做出任何假设。因为精子是用来生女儿的，反复排卵会减少精子供应，导致雌性产生更多的儿子。相比之下，如果卵子受限的雌性产生较小的后代，它们可能会使用更少的精子，从而减少精子受限的可能性。为了研究重复产卵和雌性生育力是否会影响雌性体内的配子限制，我们对六只交配的雌性黄蜂进行了两种处理，每只黄蜂以 24 或 48 小时的间隔接受一系列六名宿主。所有雌性至少产生一个混合性别的育雏（总共 63 个育雏；3,696 个后代）。正如预期的那样，如果雌性变得精子受限，在两种治疗中，随着宿主数量的增加，育雏性别比变得越来越偏向雄性。寄主间间隔不影响育雏大小、总后代数量或性别比，表明雌性没有受卵限制。我们的结果支持早期的研究表明精子耗竭影响 N 的性别分配。