Rapid evolution of Ophraella communa cold tolerance in new low-temperature environments
Zhenqi Tian, Guangmei Chen, Yan Zhang, Chao Ma, Zhenya Tian, Xuyuan Gao, Hongsong Chen, Jianying Guo & Zhongshi Zhou
近日，中国农业科学院植物保护研究所农业入侵生物预防与监控创新团队研究发现，豚草天敌昆虫广聚萤叶甲北京种群比广西种群具有更强的耐寒能力，揭示了豚草天敌广聚萤叶甲耐寒性快速适应的生理与分子遗传机制。该研究结果有助于指导在更高纬度地区豚草发生区，利用广聚萤叶甲开展有效的生物防治工作。相关研究成果发表在《昆虫科学》（Journal of Pest Science）上。
豚草原产于北美洲，是一种恶性入侵杂草，在我国华南至东北的大部分地区均有分布。广聚萤叶甲是豚草专一性天敌，对南方十几个省区市的豚草起到了非常显著的持续控制作用，有效抑制了豚草种群的扩张和蔓延。
该团队自2012年通过人工助迁的方式将广聚萤叶甲从广西来宾转移至北京门头沟地区释放，以控制豚草。结果发现，广聚萤叶甲在北京地区成功越冬并建立稳定种群，说明其耐寒性在短期内发生了快速适应性变化。
通过对广聚萤叶甲北京种群与广西来宾种群开展比较研究，发现北京种群成虫体内总糖、海藻糖、甘油、脂质和脯氨酸等耐寒性物质含量以及Tret1a、Tret1b、Tret1-2、P5CS和GST等耐寒关键基因表达水平均明显高于广西种群。
经遗传杂交实验，发现杂交子代成虫的低温保护剂和能源物质含量均高于两亲本，或介于两亲本之间；Tret1a在杂交子代中的表达模式主要呈现负面效应，其他4个基因的表达模式均呈现出积极或中等的效应，推测Trets在杂交后代中的表达可能是性连锁的，GST基因的表达具有超显性优势。
该研究得到国家自然科学基金项目的支持。
来源：中国科学报 李晨 欧阳灿彬
Abstract
Low winter temperatures severely stress newly arriving insect species. Adaptive evolutionary changes in cold tolerance can facilitate their establishment in new environments. Ambrosia artemisiifolia, a noxious invasive plant, occurs throughout China. Ophraella communa, a biological control agent of A. artemisiifolia, mainly occurs in southern China. However, in 2012, it established populations in Beijing (39.98°N, 115.97°E) following introduction from Laibin (23.62°N, 109.37°E), implying cold adaptation. The mechanisms underlying its rapid evolution of cold tolerance remain unknown. We investigated the levels of cryoprotectants and energy reserves in adult O. communa from two latitudes. In high-latitude insects, we found high trehalose, proline, glycerol, total sugar, and lipid levels; five potential genes (Tret1a, Tret1b, Tret1-2, P5CS, and GST), responsible for regulating cold tolerance and involved in trehalose transport, proline biosynthesis, and glutathione S-transferase activation, were highly expressed. These hybridisation changes could facilitate cold temperature adaptation. We demonstrate the genetic basis underlying rapid adaptation of cold tolerance in O. communa, explaining its extension to higher latitudes. Thus, specialist herbivores can follow host plants by adapting to new temperature environments via rapid genetic evolution.
