Trophic-egg producing strategies in subsocial cydnid bugs

营养蛋是不可存活的，通常作为后代的食物供应，被认为是亲代投资的延伸，或者是兄弟姐妹噬卵中父母-后代冲突的结果。triguttulus Adomerus和Parastrachia japonensis（异翅目：瓢虫科）是一种亚社会性昆虫，表现出复杂的母性照顾模式，包括防御捕食者、逐步提供寄主果实和营养性卵的生产。为了研究营养卵的功能，我们进行了从卵窝中取出营养卵的实验，并比较了有营养卵的若虫和没有营养卵的若虫的性能，包括吃活卵的发生率。营养蛋喂养提高了三角鱼和日本伪鱼后代的存活和/或发育。在A.triguttulus中，一些有活力的卵也被兄弟姐妹的若虫吃掉。然而，在有营养卵和没有营养卵的卵窝之间，活卵的消耗比例没有差异。三角鱼雌虫的体型大小影响其对营养卵的相对投资：体型较大的雌虫产的活卵较多，而营养卵相对较少。为了研究食源环境对食性卵产生的影响，我们在产卵前饲养了不同的食源环境，并比较了食性卵的分配情况。提供欠发达种子的雌性比提供发育良好种子的雌性产生的活卵少。然而，它们之间的营养卵数没有差异，因此，在提供欠发达种子的雌性中，每个活卵的营养卵数较高。根据上述两种假说和资源波动环境下的适应性母体效应，讨论了营养卵子的功能和适应性配置

Trophic eggs, which are inviable and usually function as a food supply for offspring, have been regarded as extended parental investment or the outcome of parent-offspring conflict in sibling oophagy. Adomerus triguttulus and Parastrachia japonensis (Heteroptera : Cydnidae) are subsocial bugs showing a complex pattern of maternal care, including defense against predators, progressive provisioning of host fruit and trophic-egg production.To investigate the functions of trophic eggs, we conducted experimental removal of trophic eggs from clutches and compared performance, including the incidence of viable-egg cannibalism, of nymphs with trophic eggs and those without trophic eggs. Trophic-egg feeding enhances offspring survival and/or development in A. triguttulus and P.japonensis. In A.triguttulus, some viable eggs were also fed upon by sibling nymphs. However, there was no difference in the proportion of viable eggs consumed between clutches with and without trophic eggs. The body size of A.triguttulus females affected their relative investment in trophic eggs : larger females produced more viable eggs with relatively fewer trophic eggs.To investigate the effects of food-resource environments that A.triguttulus females experience on trophic-egg production, we reared females under different resource conditions prior to oviposition and then compared the subsequent allocations of trophic eggs. Females that had been supplied with less-developed seeds produced fewer viable eggs than those supplied with well-developed seeds. However, there was no difference in the number of trophic eggs between them, and thus the number of trophic eggs per viable egg was higher in females supplied with less-developed seeds.The functions and adaptive allocation of trophic eggs are discussed in light of the two hypotheses mentioned above and the adaptive maternal effects under fluctuating resource environments