始红蝽呼吸代谢的季节变化及对温度的适应性

为阐明始红蝽呼吸代谢的季节变化规律,探讨其对温度适应的呼吸代谢策略,运用多通道昆虫呼吸仪逐月测定始红蝽自然种群的O_2吸收率、CO_2释放率、代谢率和呼吸商。基于预实验获得始红蝽完成一次完整的呼吸代谢活动的时间为90 s,故每90 s记录1次数据。结果表明,始红蝽的呼吸代谢存在明显的季节变化。冬季种群(12—2月)呼吸代谢水平最弱,O_2吸收率、CO_2释放率和代谢率的平均值依次为(3.16±1.02)×10~(-5)mL/min、(2.09±0.78)×10~(-5)m L/min、(0.11±0.08)×10-3mLg~(-1)min~(-1);春季种群(3—5月)呼吸代谢水平迅速增加,夏季种群(6—8月)呼吸代谢水平最高,O_2吸收率、CO_2释放率和代谢率的平均值分别为(33.68±2.68)×10~(-5)mL/min、(36.00±3.07)×10~(-5)m L/min、(18.16±0.83)×10-3m Lg~(-1)min~(-1);秋季种群的呼吸代谢水平开始减弱并持续到冬季。始红蝽O_2吸收率、CO_2释放率和代谢率的值与栖息地的地表温度成正相关(r_1=0.914,r_2=0.909,r_3=0.836);春、夏、秋3个季节始红蝽以糖类物质作为呼吸代谢消耗的底物,冬季则消耗脂类物质。研究得出,随季节温度变化,始红蝽不仅能够调节呼吸代谢水平的强弱以提高自身对温度的适应能力,还可通过调整呼吸代谢消耗的底物类型以最大程度降低消耗,这对维持始红蝽种群数量和扩大其地理分布具有重要的生态学意义。

Seasonal variation in respiratory metabolism and its adaptive value in Pyrrhocoris apterus

Pyrrhocoris apterus (Heteroptera:Pyrrhocoridae) is widely distributed throughout Europe and Asia and has a large range of temperature tolerance. In particular, P. apterus has strong resistance to cold owing to overwintering diapause on the soil surface near the roots of host plants. To quantify respiratory metabolism and investigate adaptation to seasonal temperature changes, O₂ uptake rate and CO₂ release rate were measured to give metabolic rates and respiratory quotients on a monthly basis for field populations of P. apterus using a multi-channel insect respiration apparatus (Sable Systems, USA). The aforementioned characteristics are strongly linked to environmental temperature and important to insect growth and development in various physiological activities. Based on an initial experiment, data recorded at 90s intervals have sufficient details, and a total of 45 individuals were collected from the field and examined at the laboratory every month (Oct 2013 to Sep 2014), the measurements were repeated three times for each individual. Results showed that the respiratory metabolism of P. apterus has a distinct seasonal variation. The lowest values occurred in winter (December-February); the average values of O₂ uptake rate, CO₂ release rate, and metabolic rate were (3.16±1.02)×10^-5 mL/min, (2.09±0.78)×10^-5 mL/min, and (0.11±0.08)×10^-3 mL g^-1 min^-1, respectively. Respiratory metabolic rate increased rapidly in spring from March to May and peaked in summer from June to August; the values of O₂ uptake rate, CO₂ release rate, and metabolic rate were (33.68±2.68)×10^-5 mL/min, (36.00±3.07)×10^-5 mL/min, and (18.16±0.83)×10^-3 mL g^-1 min^-1, respectively. The respiratory metabolism decreased from autumn to winter. Results showed a clear positive correlation between ground surface temperature and respiratory metabolism of P. Apterus (r₁=0.914, r₂=0.909, r₃=0.836 for O₂ uptake rate, CO₂ release rate, and metabolic rate, respectively). We found that the RQ value we measured were from 0.71-0.97 and P. apterus used carbohydrates as a substrate for respiratory metabolism in spring, summer, and autumn, whereas lipid was mostly consumed in winter. This study indicated that P.apterus can adjust its respiratory metabolism according to the trend of environmental temperatures and use different substrates to vary metabolic rate, which may reflect adaptations enabling P. apterus to maintain its persistent, widely distributed metapopulation. These results elucidate the dynamic changes of respiratory metabolism of P. apterus in response to seasonal temperature changes, and provide a foundation for further study on how the biochemical mechanism of a P.apterus field population has enabled this species to adapt to the environment.