Yu Ming-Qing, Linghu Jun-Hong, Xie Hua-Yan, Li Gang, Zhu Feng, Smagghe Guy, Gui Shun-Hua, Liu Tong-Xian
Guizhou Provincial Key Laboratory for Agricultural Pest Management of the Mountainous Region, Institute of Entomology, Guizhou University, Guiyang, China.
Guizhou Center for Pesticide Risk Monitoring, Institute of Plant Protection, Guizhou Academy of Agricultural Sciences, Guiyang, China.
Insect Sci. 2025 Jan 6. doi: 10.1111/1744-7917.13480.
Feeding and molting are particularly important physiological processes for insects, and it has been reported that neuropeptides are involved in the nervous regulation of these 2 processes. Sulfakinin (SK) is an important neuropeptide that is widely distributed among insects and plays a pivotal role in regulating feeding, courtship, aggression, and locomotion. In this study, we investigated the involvement of SK in feeding and molting on a highly notorious pest insect, the fall armyworm, Spodoptera frugiperda. SK transcript levels were found in all larval stages and there was a predominant expression of SK in the brain of 5th instar larvae. By immunostaining, SK was detected in 2 pairs of cells in the median protocerebrum. But during prolonged periods of starvation, there was a significant reduction in SK messenger RNA levels; however, subsequent refeeding led to a notable increase. To investigate the role of SK in feeding and molting, SK was silenced in S. frugiperda larvae through RNA interference. This resulted in a significant increase in food intake, weight gain, and the molting process happened more rapidly in the double-stranded SK-treated larvae compared to the controls. Conversely, injection of sulfated SK peptide (sSK) caused opposite effects. Interestingly, SK-knockdown in larvae resulted in increased levels of 20-hydroxyecdysone and also of the expression of some of it signaling pathway genes. Altogether, this study highlights the important role played by SK in regulating feeding and molting in S. frugiperda.
取食和蜕皮是昆虫尤为重要的生理过程，据报道神经肽参与这两个过程的神经调节。速激肽（SK）是一种重要的神经肽，广泛分布于昆虫中，在调节取食、求偶、攻击和运动中起关键作用。在本研究中，我们调查了速激肽在一种臭名昭著的害虫——草地贪夜蛾（Spodoptera frugiperda）的取食和蜕皮过程中的作用。在所有幼虫阶段均检测到速激肽转录水平，且在5龄幼虫的脑中速激肽表达占主导。通过免疫染色，在中脑原脑的2对细胞中检测到了速激肽。但在长期饥饿期间，速激肽信使核糖核酸水平显著降低；然而，随后重新喂食导致其显著增加。为了研究速激肽在取食和蜕皮中的作用，通过RNA干扰使草地贪夜蛾幼虫中的速激肽沉默。这导致取食量显著增加、体重增加，与对照相比，双链速激肽处理的幼虫蜕皮过程发生得更快。相反，注射硫酸化速激肽肽（sSK）则产生相反的效果。有趣的是，幼虫中速激肽敲低导致20-羟基蜕皮酮水平升高，其一些信号通路基因的表达也增加。总之，本研究突出了速激肽在调节草地贪夜蛾取食和蜕皮中所起的重要作用。
