Güney Gözde, Cedden Doga, Körnig Johannes, Ulber Bernd, Beran Franziska, Scholten Stefan, Rostás Michael
Agricultural Entomology, Department of Crop Sciences, University of Göttingen, D-37077, Göttingen, Germany.
Department of Evolutionary Developmental Genetics, Johann-Friedrich-Blumenbach Institute, GZMB, University of Göttingen, D-37077, Göttingen, Germany.
Insect Biochem Mol Biol. 2024 Oct;173:104165. doi: 10.1016/j.ibmb.2024.104165. Epub 2024 Jul 30.
Aestivation is a form of seasonal dormancy observed in various insect species, usually coinciding with the summer season. The cabbage stem flea beetle, Psylliodes chrysocephala (Coleoptera: Chrysomelidae), is a key pest of oilseed rape that obligatorily aestivates as adult in late summer. Since the physiological and transcriptional processes linked to aestivation in P. chrysocephala are still little understood, we analyzed relevant physiological parameters and performed RNA-seq analyses on laboratory-reared beetles in their pre-aestivation, aestivation, and post-aestivation stages. We found that the beetles reached aestivation at 15 days post-eclosion, showing strongly reduced metabolic activity, with less than 50% CO production, compared to pre-aestivating individuals. Under constant laboratory conditions, the beetles aestivated for about 25 days. Female beetles reached reproductive maturity at a median of 52 days post-eclosion. Furthermore, aestivating beetles had significantly reduced carbohydrate reserves and increased lipid reserves compared with pre-aestivating beetles, indicating that aestivation is associated with drastic changes in energy metabolism. Aestivating beetles contained 30% less water and their survival rates under high-temperature conditions (30 °C) were 40% higher compared to pre-aestivating beetles. RNA-seq studies showed that, in particular, gene ontology terms related to carbohydrate and lipid metabolism, digestion, and mitochondrial activity were enriched, with clear differences in transcript abundance between beetles in aestivation compared to pre- or post-aestivation. Specifically, mitochondrial transcripts, such as respiratory chain I subunits, and digestion-related transcripts, such as trypsin, were less abundant during aestivation, which supports the idea that aestivation is associated with decreased metabolic activity. This study represents the first exploration of the transcriptomic and physiological processes linked to aestivation in P. chrysocephala.
夏眠是在多种昆虫物种中观察到的一种季节性休眠形式，通常与夏季一致。甘蓝茎跳甲（Psylliodes chrysocephala，鞘翅目：叶甲科）是油菜的一种关键害虫，成虫在夏末必须进行夏眠。由于与甘蓝茎跳甲夏眠相关的生理和转录过程仍知之甚少，我们分析了相关生理参数，并对实验室饲养的处于夏眠前、夏眠期和夏眠后的甲虫进行了RNA测序分析。我们发现，甲虫在羽化后15天进入夏眠状态，与夏眠前的个体相比，其代谢活动大幅降低，二氧化碳产生量减少了50%以上。在恒定的实验室条件下，甲虫夏眠约25天。雌性甲虫在羽化后第52天达到生殖成熟。此外，与夏眠前的甲虫相比，处于夏眠状态的甲虫碳水化合物储备显著减少，脂质储备增加，这表明夏眠与能量代谢的剧烈变化有关。处于夏眠状态的甲虫含水量减少30%，在高温条件（30°C）下的存活率比夏眠前的甲虫高40%。RNA测序研究表明，特别是与碳水化合物和脂质代谢、消化以及线粒体活性相关的基因本体术语得到了富集，与夏眠前或夏眠后的甲虫相比，处于夏眠状态的甲虫转录本丰度存在明显差异。具体而言，线粒体转录本，如呼吸链I亚基，以及与消化相关的转录本，如胰蛋白酶，在夏眠期间丰度较低，这支持了夏眠与代谢活动降低相关的观点。本研究首次探索了与甘蓝茎跳甲夏眠相关的转录组和生理过程。
