Data from: Sex allocation theory reveals a hidden cost of neonicotinoid exposure in a parasitoid wasp

Sex allocation theory has proved to be one the most successful theories in evol- utionary ecology. However, its role in more applied aspects of ecology has been limited. Here we show how sex allocation theory helps uncover an other- wise hidden cost of neonicotinoid exposure in the parasitoid wasp Nasonia vitripennis. Female N. vitripennis allocate the sex of their offspring in line with Local Mate Competition (LMC) theory. Neonicotinoids are an eco- nomically important class of insecticides, but their deployment remains controversial, with evidence linking them to the decline of beneficial species. We demonstrate for the first time that neonicotinoids disrupt the crucial repro- ductive behaviour of facultative sex allocation at sub-lethal, field-relevant doses in N. vitripennis. The quantitative predictions we can make from LMC theory show that females exposed to neonicotinoids are less able to allocate sex optimally and that this failure imposes a significant fitness cost. Our work highlights that understanding the ecological consequences of neonicoti- noid deployment requires not just measures of mortality or even fecundity reduction among non-target species, but also measures that capture broader fitness costs, in this case offspring sex allocation. Our work also highlights new avenues for exploring how females obtain information when allocating sex under LMC.性别分配理论已被证实为进化生态学中最具影响力的理论之一。然而，该理论在生态学更具应用价值的领域中尚未得到充分发挥。本研究揭示了性别分配理论如何帮助发掘寄生蜂**丽蝇蛹集金小蜂（Nasonia vitripennis）**在暴露于**新烟碱类杀虫剂（neonicotinoid）**时原本被掩盖的生存代价。雌性丽蝇蛹集金小蜂会依据**局部配偶竞争（Local Mate Competition, LMC）**理论来决定子代的性别比例。新烟碱类杀虫剂是一类经济价值极高的杀虫剂，但其使用仍存在广泛争议——多项研究证据表明其与有益昆虫种群的衰退存在关联。本研究首次证实，在符合田间实际浓度的亚致死剂量下，新烟碱类杀虫剂会干扰丽蝇蛹集金小蜂的兼性性别分配这一关键生殖行为。基于LMC理论可做出的定量预测显示，暴露于新烟碱类杀虫剂的雌性个体无法最优地调整子代性别比例，这一缺陷会带来显著的适合度代价。本研究表明，要全面理解新烟碱类杀虫剂使用带来的生态后果，不仅需要评估非靶标物种的死亡率乃至繁殖力下降情况，还需量化其更广泛的适合度代价——在本研究中即子代性别分配的异常。此外，本研究还为探索雌性个体在LMC框架下进行性别分配时如何获取相关信息提供了全新的研究方向。