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. 卵生物种的卵通常承受强烈的捕食压力。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体色醒目的卵（即警戒色（aposematism））。2. 瓢虫卵体色醒目且含有生物碱；学界普遍认为，这两类性状分别作为视觉信号与化学防御手段协同发挥作用，以抵御捕食者。然而目前仍未明确，这类警戒色是否能够传递化学防御的强度信息（而非仅表明防御的存在）。3. 此外，卵内色素与毒素或存在其他功能：具体而言，亲本可能将这类物质沉积于卵中，以辅助后代发育，或是为子代的警戒色性状形成提供物质基础。4. 本研究在实验室中繁育了野外捕获的七星瓢虫（Coccinella septempunctata），随后检测了卵体色与毒素（即前瓢虫碱（precoccinelline）与瓢虫碱（coccinelline））浓度之间的相关性；同时测定了卵类胡萝卜素（carotenoids）与卵体色的关联、卵体色与毒素水平的关联，并针对部分允许发育至羽化的卵，检测了其子代羽化时的鞘翅（elytra）体色与体内毒素浓度的关系。5. 卵类胡萝卜素水平可预测卵的颜色饱和度；而卵的颜色饱和度与色调均可正向预测前瓢虫碱的卵内浓度。但卵内瓢虫碱浓度与任何卵体色指标均无显著相关性。6. 雌雄两性刚羽化成虫的鞘翅饱和度，均可通过卵的饱和度与色调的变化得到显著解释。最终，成虫体内的瓢虫碱浓度可通过鞘翅色调的变化显著预测。7. 上述结果表明，七星瓢虫卵的体色是其体内化学防御强度的可靠信号；此外，亲本向卵中投入的色素与毒素，或可影响子代警戒色信号的可靠性。