Recent reports demonstrate that octopamine plays an important immunological role in crowded larvae of the Oriental Armyworm, Mythmina separata. We identified an octopamine receptor, the β-adrenergic-like gene (designated MsOctβ2R), with a 1191 bp open reading frame that encodes 396 amino acids and contains seven conserved hydrophobic transmembrane domains. Multiple sequence alignments and a phylogenetic analysis indicated that MsOctβ2R was orthologous to Octβ2R that is present in other lepidopterans. MsOctβ2R was expressed throughout all developmental stages with higher relative expression during the fourth instar and adult stages. MsOctβ2R was highly expressed in the ventral nerve cord and the fat body relative to other examined tissues. Elevated MsOctβ2R expression was observed in larvae that were under higher-density conditions (7 and 10 larvae per jar). Silencing MsOctβ2R expression via dsRNA injections in larvae from higher-density conditions significantly decreased phenoloxidase (PO) and lysozyme activity, total haemocyte counts, and survival rates against Beauveria bassiana infections (54.06%, 9.91%, 36.22%, and 23.53%, respectively) when compared with control larvae. These results suggest that high-density conditions might alter prophylactic immunity in larvae by regulating the MsOctβ2R gene in M. separara and provide new insights into density-dependent prophylaxis in insects.

最近的报告表明，章鱼胺在东方粘虫 Mythmina separata 的拥挤幼虫中起着重要的免疫作用。我们鉴定了一种章鱼胺受体，β-肾上腺素能样基因（命名为MsOctβ2R），具有 1191 bp 的开放阅读框，可编码 396 个氨基酸并包含七个保守的疏水跨膜结构域。多序列比对和系统发育分析表明MsOctβ2R是直向同源至Octβ2R存在于其他鳞翅目昆虫。MsOctβ2R在所有发育阶段均有表达，在四龄和成虫阶段相对表达较高。MsOctβ2R相对于其他检查的组织，在腹神经索和脂肪体中高度表达。在较高密度条件下（每罐 7 和 10 只幼虫）的幼虫中观察到MsOctβ2R表达升高。在高密度条件下，通过注射 dsRNA 在幼虫中沉默MsOctβ2R表达显着降低酚氧化酶 (PO) 和溶菌酶活性、血细胞总数和对抗白僵菌感染的存活率（分别为 54.06%、9.91%、36.22% 和 23.53%）与对照幼虫相比。这些结果表明高密度条件可能通过调节M. separara 中的MsOctβ2R基因来改变幼虫的预防性免疫 并为昆虫的密度依赖性预防提供新的见解。