Intra- and trans-generational effects of larval diet on susceptibility to an entomopathogenic fungus, Beauveria bassiana, in the greater wax moth, Galleria mellonella

In addition to nutritional conditions experienced by individuals themselves, those experienced by their parents can affect their immune function. Here, we studied the intra- and trans-generational effects of larval diet on susceptibility to an entomopathogenic fungus, Beauveria bassiana, in the greater wax moth, Galleria mellonella. In the first part of the study, a split-brood design was used to compare the susceptibility of full sibs raised either on low- or on high-nutrition larval diet. In the second part of the study, a similar experimental design was employed to investigate the effects of maternal and paternal diet as well as their interaction on offspring's susceptibility. In the first part of the study, we found that individuals fed with high-nutrition diet had higher mortality from infection than individuals fed with low-nutrition diet. However, diet did not affect post-infection survival time. Conversely, in the second part of the study, maternal diet was found to have no significant effect on final mortality rate of offspring, but it affected survival time: larvae with high-nutrition maternal diet survived fewer days after infection than larvae with low-nutrition maternal diet. Paternal diet had no significant effect on offspring's susceptibility to the fungus, indicating that paternal effects are not as important as maternal effects in influencing immune function in this species. Our findings provide further indication that maternal nutrition affects immune function in insects, and suggest that the direct effects of nutrition on immunity may be different, yet parallel, to those caused by parental nutrition.

除个体自身经历的营养状况外，其父母所经历的营养状况亦可影响个体的免疫功能。本研究以大蜡螟（Galleria mellonella）为研究对象，探究幼虫日粮对其感染虫生真菌（entomopathogenic fungus）球孢白僵菌（Beauveria bassiana）易感性的代内效应与跨代效应。研究第一部分采用裂群设计（split-brood design），对比了以低营养或高营养幼虫日粮饲养的全同胞个体的感染易感性。研究第二部分采用相似实验设计，旨在探究母本日粮、父本日粮及其交互作用对子代感染易感性的影响。第一部分实验结果显示，饲喂高营养日粮的个体，其感染后的死亡率显著高于饲喂低营养日粮的个体，但日粮并未对感染后存活时间产生显著影响。与之相反，第二部分实验结果表明，母本日粮对子代的最终死亡率无显著影响，但会影响子代的感染后存活时间：母本饲喂高营养日粮的幼虫，感染后的存活天数显著少于母本饲喂低营养日粮的幼虫。父本日粮对子代的真菌感染易感性无显著影响，这表明在该物种中，父本效应对免疫功能的影响程度不及母本效应。本研究结果进一步证实，母本营养状况可影响昆虫的免疫功能，并提示营养对免疫的直接效应与亲代营养所引发的效应虽存在差异，但具有相似性。