Department of Entomology, Nanjing Agricultural University, Nanjing, China.
Beijing Key Laboratory of Bioelectromagetics, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing, China.
Insect Sci. 2021 Feb;28(1):251-260. doi: 10.1111/1744-7917.12765. Epub 2020 Jun 25.
The geomagnetic field (GMF) is well documented for its essential role as a cue used in animal orientation or navigation. Recent evidence indicates that the absence of GMF (mimicked by the near-zero magnetic field, NZMF) can trigger stress-like responses such as reduced body weight, as we have previously shown in the brown planthopper, Nilaparvata lugens. In this study, we found that consistent with the significantly decreased body weight of newly emerged female (-14.67%) and male (-13.17%) adult N. lugens, the duration of the phloem ingestion feeding waveform was significantly reduced by 32.02% in 5th instar nymphs reared under the NZMF versus GMF. Interestingly, 5th instar nymphs that exhibited reduced feeding had significantly higher glucose levels (+16.98% and +20.05%; 24 h and 48 h after molting), which are associated with food aversion, and expression patterns of their appetite-related neuropeptide genes (neuropeptide F, down-regulated overall; short neuropeptide F, down-regulated overall; adipokinetic hormone, up-regulated overall; and adipokinetic hormone receptor, down-regulated overall) were also altered under the absence of GMF in a manner consistent with diminishing appetite. Moreover, the expressions of the potential magnetosensor cryptochromes (Crys) were found significantly altered under the absence of GMF, indicating the likely upstream signaling of the Cry-mediated magnetoreception mechanisms. These findings support the hypothesis that strong changes in GMF intensity can reduce adult body weight through affecting insect feeding behavior and underlying regulatory processes including appetite regulation. Our results highlight that GMF could be necessary for the maintenance of energy homeostasis in insects.
地磁场（GMF）在动物的定向或导航中起着重要的线索作用，这一点已有充分的记录。最近的证据表明，缺乏地磁场（由近零磁场模拟，NZMF）会引发类似压力的反应，如体重减轻，我们之前在褐飞虱Nilaparvata lugens 中已经观察到了这种情况。在这项研究中，我们发现，与新出现的雌性（-14.67%）和雄性（-13.17%）成年褐飞虱的体重明显下降一致，在 NZMF 下饲养的 5 龄若虫的韧皮部取食波型持续时间比 GMF 下显著减少了 32.02%。有趣的是，表现出摄食减少的 5 龄若虫的葡萄糖水平显著升高（24 小时和 48 小时后蜕皮时分别升高了 16.98%和 20.05%），这与对食物的厌恶有关，并且与食欲相关的神经肽基因（神经肽 F，整体下调；短神经肽 F，整体下调；激素激活肽，整体上调；和激素激活肽受体，整体下调）的表达模式也在 GMF 缺失的情况下发生改变，这与食欲减退一致。此外，在缺乏 GMF 的情况下，潜在的磁受体隐花色素（Crys）的表达也明显发生改变，表明 Cry 介导的磁受体机制可能存在上游信号。这些发现支持这样的假设，即 GMF 强度的强烈变化可以通过影响昆虫的取食行为和包括食欲调节在内的潜在调节过程来降低成虫的体重。我们的研究结果强调，GMF 可能是昆虫维持能量平衡所必需的。
