麦长管蚜的低温适应性及陕西杨凌小麦田春季虫源分析

【目的】本研究旨在探明低温条件下麦长管蚜Sitobion avenae的存活率和快速冷驯化反应,以期为该虫耐寒性的研究和准确预测预报提供依据。【方法】测定麦长管蚜实验室种群各发育阶段的过冷却点和结冰点;测定1龄若蚜和未产仔成蚜分别在-7.0～-11.0℃极端低温下暴露3 h和在0℃冷驯化1～5 h后暴露于致死温度3 h,再转移至15℃72 h后的存活率;调查自然条件下陕西杨凌小麦整个生育期麦长管蚜的种群动态。【结果】麦长管蚜1龄和2龄若蚜的过冷却点波动范围较小,分别为-27.4～-19.2℃和-27.3～-18.3℃;3龄若蚜、4龄若蚜和成蚜的过冷却点波动范围较大,分别为-27.4～-10.7℃,-26.7～-12.5℃和-26.7～-11.2℃。麦长管蚜的过冷却点和结冰点随龄期增加均显著升高,其中成蚜的过冷却点显著高于1龄和2龄若蚜。3龄若蚜、4龄若蚜和成蚜的过冷却点在不同翅型之间不存在显著性差异。低温存活率分析表明,麦长管蚜1龄若蚜和无翅成蚜的致死温度(80%死亡率)分别在-10.5℃和-8.1℃左右。0℃快速冷驯化显著提高了麦长管蚜1龄若蚜和无翅成蚜在极端低温下的存活率,其中冷驯化2 h时的存活率最高。2018-2019年小麦生育期田间调查结果表明,麦长管蚜能以孤雌生殖若蚜和成蚜在陕西杨凌越冬。【结论】麦长管蚜具有较强的低温适应能力,在陕西杨凌能以孤雌生殖蚜成功越冬。因此,其本地越冬存活个体是陕西杨凌小麦田的早春虫源之一。

Low temperature adaptability ofSitobion avenae(Hemiptera: Aphididae) and its spring source in wheat fields in Yangling,Shaanxi, northwestern China

【Aim】 This study aims to clarify the survival rate and response to rapid cold acclimation in the grain aphid, Sitobion avenae, under extremely low temperature so as to provide a basis for the study of cold tolerance and accurate prediction of this insect. 【Methods】 The supercooling point and freezing point of the laboratory population of S. avenae at various developmental stages were determined, the survival rates of the 1st instar nymphs and the apterous adults exposed to extremely low temperature from -7℃ to -11℃ for 3 h and those exposed to lethal temperature for 3 h after cold acclimation at 0℃ for 1-5 h, respectively, and then transferred to 15℃ for 72 h, were assessed, and the population dynamics of S. avenae was investigated during the whole wheat growth period in Yangling, Shaanxi, northwestern China. 【Results】 The supercooling points of the 1st and 2nd instar nymphs of S. avenae showed a small fluctuation from -27.4℃ to -19.2℃ and from -27.3℃ to -18.3℃, respectively, while those of the 3rd and 4th instar nymphs and adults showed a large fluctuation from -27.4℃ to -10.7℃, from -26.7℃ to -12.5℃, and from -26.7℃ to -11.2℃, respectively. The supercooling point and freezing point of S. avenae increased significantly with the increasing instars. The supercooling point of adults was significantly higher than those of the 1st and 2nd instar nymphs. There were no significant differences in the supercooling points of the 3rd and 4th instar nymphs and adults between the alate and apterous morphs at the same developmental stage. The analysis of survival rate at low temperature showed that the lethal temperatures (80% mortality) for the 1st instar nymphs and apterous adults remained around -10.5℃ and -8.1℃, respectively. The rapid cold acclimation at 0℃ improved significantly the survival rate of the 1st instar nymphs and apterous adults at extremely low temperature, with the highest survival rate after cold acclimation for 2 h. The results of field investigation from 2018 to 2019 revealed that S. avenae could overwinter as parthenogenetic nymphs and adults in Yangling, Shaanxi. 【Conclusion】 S. avenae shows strong low temperature adaptability. Its parthenogenetic aphids can overwinter successfully in Yangling, Shaanxi. These results suggest that aphids in the wheat field in early spring may source partly from the survived locally overwintering individuals of this aphid.