Immune assay data for Lycaeides melissa larvae reared on different host plants and with/without egg microbes

1. Maternally transmitted microbes are ubiquitous. In insects, maternal microbes can play a role in mediating the insect immune response. Less is known about how ecological factors, such as resource use, interact with maternal microbes to affect immunity. 2. In the context of a recent colonization of a novel host plant by the Melissa blue butterfly (Lycaeides melissa), we investigated the interaction between host plant use and vertically transmitted, extracellular egg-associated microbes in determining the strength of the insect immune response. 3. We reared larvae on two different host plant species: a native host Astragalus canadensis and a novel host Medicago sativa. Egg-associated microbes were removed through a series of antimicrobial egg washes prior to hatching. Immune response was measured through three assays: standing phenoloxidase (PO), total PO, and melanization. 4. We detected strong effects of microbial removal. Egg washing resulted in larvae with an increased immune response as measured by total PO- contrary to reports from other taxa. The effect of washing was especially strong for larvae consuming the native host plant. 5. This result may explain why consumption of the egg casing is not a universal behaviour in insects, due to negative effects on larval immunity.1. 母体传播微生物（maternally transmitted microbes）广泛存在于自然界中。在昆虫类群内，母体微生物可参与调控宿主的免疫应答过程。目前关于资源利用等生态因子如何与母体微生物相互作用以影响昆虫免疫功能的相关研究仍相对不足。2. 针对梅利莎蓝蝶（Lycaeides melissa）近期定殖新型寄主植物的研究背景，本研究探讨了寄主植物利用模式与垂直传播的胞外卵相关微生物（extracellular egg-associated microbes）在调控昆虫免疫应答强度中的互作关系。3. 我们将幼虫分别饲养于两种寄主植物上：原生寄主加拿大黄芪（Astragalus canadensis）与新型寄主紫花苜蓿（Medicago sativa）。在幼虫孵化前，通过多轮抗菌卵清洗操作去除卵表面附着的相关微生物。我们通过三项检测实验量化免疫应答水平：静息酚氧化酶（standing phenoloxidase, PO）、总酚氧化酶（total PO）以及黑化反应（melanization）。4. 实验结果显示微生物去除存在显著效应：与其他类群的已有研究结论相反，经卵清洗处理的幼虫，其总酚氧化酶水平所反映的免疫应答显著升高；且该清洗效应在取食原生寄主植物的幼虫群体中尤为突出。5. 该研究结果或可解释为何取食卵壳并非昆虫的普遍行为——这是由于取食卵壳会对幼虫的免疫功能产生负面影响。