Data from: Maternal effects and warning signal honesty in eggs and offspring of an aposematic ladybird beetle

1. The eggs of oviparous species are often subject to intense predation pressure. One parental strategy to deter predators is to produce eggs that are laced with noxious chemicals and are conspicuously coloured (i.e. aposematism). 2. Ladybird eggs are conspicuously coloured and contain alkaloids; these traits are believed to function in concert as visual signal and chemical defence, respectively, to deter predators. However, it remains unclear whether such aposematic signals reveal the strength (rather than simply the existence) of chemical defences. 3. Furthermore, additional functions of egg pigments and toxins could apply; in particular mothers might deposit such resources into eggs to aid the development of offspring, or to provide resources that could contribute to aposematic traits in offspring. 4. We bred wild-caught seven-spot ladybird beetles (Coccinella septempunctata) in the laboratory, and then measured relationships between egg colouration and toxin concentrations (i.e. the alkaloids precoccinelline and coccinelline). We also measured relationships between egg carotenoids and egg colouration, and between egg colouration and toxin levels, and the elytra colouration and toxin concentrations of offspring at eclosion for a subset of eggs that were allowed to develop. 5. Egg carotenoids predicted egg colour saturation. In turn egg colour saturation and hue positively predicted egg concentrations of precoccinelline. However, there were no significant relationships between egg coccinelline concentration and any measure of egg colouration. 6. In recently eclosed adults of both sexes elytra saturation was significantly explained by variation in egg saturation and hue. Finally, body concentrations of coccinelline were significantly explained by variation in elytra hue. 7. These results suggest that the colouration of C. septempunctata eggs is a reliable signal of the strength of chemical defences contained therein, but in addition, maternal investment of pigments and toxins into eggs may serve to influence the reliability of aposematic signalling in resultant offspring.

1. 卵生动物的卵往往面临强烈的捕食压力。一种用于威慑捕食者的亲本策略是产出携带有毒化学物质且色彩醒目的卵（即警戒色（aposematism））。2. 瓢虫卵色彩醒目且含有生物碱；学界普遍认为这两种性状分别作为视觉信号与化学防御手段协同发挥威慑捕食者的作用。然而目前仍不清楚这类警戒色信号是否能够反映化学防御的强度（而非仅仅表明其存在）。3. 此外，卵内色素与毒素可能还存在其他功能：具体而言，亲本可将这类物质沉积于卵中，以辅助子代发育，或是为子代提供有助于其形成警戒性状的资源。4. 本研究在实验室中繁育野外捕获的七星瓢虫（Coccinella septempunctata），随后测定了卵的体色与毒素浓度（即生物碱类的前瓢虫碱（precoccinelline）与瓢虫碱（coccinelline））之间的关联；同时还测定了卵类胡萝卜素含量与卵体色的关联、卵体色与毒素水平的关联，以及对部分发育至羽化的子代个体，其鞘翅（elytra）体色与羽化时体内毒素浓度之间的关联。5. 卵内类胡萝卜素含量可预测卵的色彩饱和度；而卵的色彩饱和度与色调可正向预测卵内前瓢虫碱的浓度。不过卵内瓢虫碱浓度与卵体色的各项指标均无显著关联。6. 雌雄两性刚羽化的成虫，其鞘翅饱和度均可通过卵的饱和度与色调的变化得到显著解释；最终，成虫体内瓢虫碱的浓度可通过鞘翅色调的变化得到显著预测。7. 上述结果表明，七星瓢虫卵的体色是其内部化学防御强度的可靠信号；此外，母本向卵中投入色素与毒素的行为，或可影响子代警戒信号传递的可靠性。