The response of insects to orally delivered double-stranded RNA ranges widely among taxa studied to date. Long dsRNA does elicit a response in stink bugs but the dose required to achieve an effect is relatively high compared to other insects such Colorado potato beetle or western corn rootworm. Improving the delivery of dsRNA to stink bugs will improve the likelihood of using RNA-based biocontrols for the management of these economically important pests. Short hairpin RNA (shRNA) is a useful molecule with which to test improvements in the delivery of double stranded RNA in the neotropical brown stink bug, Euschistus heros, since shRNA alone does not elicit a clear effect like that for long dsRNA. Here, we show for the first time the oral delivery of shRNA triggering RNA interference (RNAi) in E. heros using 4 nm cerium oxide nanoparticles (CeO₂ NPs) coated with diethylamioethyl dextran (Dextran-DEAE) as a carrier. We identified particle properties (coating composition and degree of substitution, hydrodynamic diameter, and zeta potential) and shRNA loading rates (Ce:shRNA mass ratio) that resulted in successful transcript reduction or RNAi. When the Z-average diameter of CeO₂ Dextran-DEAE-shRNA NP complex was less than 250 nm and the zeta potential was in the 15–25 mV range (Ce:shRNA mass ratio of 0.7:1), significant mortality attributed to RNAi was observed with a shRNA concentration in feeding solution of 250 ng/μl. The degradation of the targeted troponin transcript by NP-delivered shRNA was equivalent to that observed with long dsRNA, while naked shRNA transcript reduction was not statistically significant. Elemental mapping by synchrotron X-ray fluorescence microprobe confirmed uptake and distribution of Ce throughout the body with the highest concentrations found in gut tissue. Taken together, our results suggest that a nanoparticle delivery system can improve the delivery of RNA-based biocontrols to E. heros, and therefore its attractiveness as an application in the management of this important pest in soybean production.

在迄今为止研究的分类群中，昆虫对口服双链 RNA 的反应范围很广。长 dsRNA 确实会引起臭虫的反应，但与其他昆虫（如科罗拉多马铃薯甲虫或西部玉米根虫）相比，达到效果所需的剂量相对较高。改善 dsRNA 向臭虫的传递将提高使用基于 RNA 的生物防治来管理这些具有重要经济意义的害虫的可能性。短发夹 RNA (shRNA) 是一种有用的分子，用于测试新热带棕色臭虫Euschistus heros 中双链 RNA 递送的改进，因为单独的 shRNA 不会像长 dsRNA 那样引起明显的效果。在这里，我们首次展示了 shRNA 的口服递送触发 RNA 干扰 (RNAi)E. heros使用涂有二乙基氨基乙基葡聚糖 (Dextran-DEAE) 作为载体的4 nm 氧化铈纳米颗粒 (CeO ₂ NPs)。我们确定了导致成功转录减少或 RNAi 的粒子特性（涂层组成和取代程度、流体动力学直径和 zeta 电位）和 shRNA 加载率（Ce:shRNA 质量比）。当CeO ₂的Z均直径葡聚糖-DEAE-shRNA NP 复合物小于 250 nm，zeta 电位在 15-25 mV 范围内（Ce:shRNA 质量比为 0.7:1），在喂食溶液中的 shRNA 浓度下观察到归因于 RNAi 的显着死亡率250 纳克/微升。NP 传递的 shRNA 对目标肌钙蛋白转录物的降解与用长 dsRNA 观察到的相同，而裸 shRNA 转录物的减少没有统计学意义。通过同步加速器 X 射线荧光微探针进行的元素映射证实了 Ce 在整个身体中的吸收和分布，在肠道组织中发现的浓度最高。综上所述，我们的结果表明，纳米颗粒递送系统可以改善基于 RNA 的生物防治对E. heros的递送，因此它在管理这种大豆生产中的重要害虫方面具有吸引力。