In hymenopterans, males are normally haploid (1n) and females diploid (2n), but individuals with divergent ploidy levels are frequently found. In species with ‘complementary sex determination’ (CSD), increasing numbers of diploid males that are often infertile or unviable arise from inbreeding, presenting a major impediment to biocontrol breeding. Non‐CSD species, which are common in some parasitoid wasp taxa, do not produce polyploids through inbreeding. Nevertheless, polyploidy also occurs in non‐CSD Hymenoptera. As a first survey on the impacts of inbreeding and polyploidy of non‐CSD species, we investigate life‐history traits of a long‐term laboratory line of the parasitoid Nasonia vitripennis (Walker) (Hymenoptera: Pteromalidae) (‘Whiting polyploid line’) in which polyploids of both sexes (diploid males, triploid females) are viable and fertile. Diploid males produce diploid sperm and virgin triploid females produce haploid and diploid eggs. We found that diploid males did not differ from haploid males with respect to body size, progeny size, mate competition, or lifespan. When diploid males were mated to many females (without accounting for mating order), the females produced a relatively high proportion of male offspring, possibly indicating that these males produce less sperm and/or have reduced sperm functionality. In triploid females, parasitization rate and fecundity were reduced and body size was slightly increased, but there was no effect on lifespan. After one generation of outbreeding, lifespan as well as parasitization rate were increased, and a body size difference was no longer apparent. This suggests that outbreeding has an effect on traits observed in an inbred polyploidy background. Overall, these results indicate some phenotypic detriments of non‐CSD polyploids that must be taken into account in breeding.

中文翻译：

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寄生蜂 Nasonia vitripennis Whiting 多倍体系的生活史特征

在膜翅目中，雄性通常是单倍体 (1n) 和雌性二倍体 (2n)，但经常发现具有不同倍性水平的个体。在具有“互补性别决定”(CSD) 的物种中，越来越多的通常不育或无法生存的二倍体雄性来自近亲繁殖，这是生物防治育种的主要障碍。在一些寄生蜂类群中常见的非 CSD 物种不会通过近亲繁殖产生多倍体。然而，多倍体也发生在非 CSD 膜翅目中。作为对非 CSD 物种近亲繁殖和多倍体影响的首次调查，我们调查了寄生蜂 Nasonia vitripennis (Walker)（膜翅目：Pteromalidae）（'Whiting polyploid line'）长期实验室品系的生活史特征其中两性的多倍体（二倍体雄性，三倍体雌性）是有活力和可育的。二倍体雄性产生二倍体精子，处女三倍体雌性产生单倍体和二倍体卵。我们发现二倍体雄性在体型、后代大小、配偶竞争或寿命方面与单倍体雄性没有区别。当二倍体雄性与许多雌性交配时（不考虑交配顺序），雌性产生了相对较高比例的雄性后代，这可能表明这些雄性产生的精子较少和/或精子功能降低。在三倍体雌性中，寄生率和繁殖力降低，体型略有增加，但对寿命没有影响。经过一代远交后，寿命增加，寄生率增加，体型差异不再明显。这表明远交对近交多倍体背景中观察到的性状有影响。总体而言，这些结果表明非 CSD 多倍体的一些表型损害必须在育种中加以考虑。