Effects Of Climate Change On Life History And Potential Habitat Distribution Of Mythimna Separate (Walker)

In this thesis study, we used Mythimna separata (Walker) as model system, to examine influence of elevated CO2on life history traits, and made a projection of habitats with increasing temperature of2℃using CLIMEX and ArcGis. The main results and conclusions obtained from this study were summarized below.1. Effects of elevated CO2on life history traits of Mythimna separateCO2concentration was manipulated as two levels, ambient (390uL/L) and elevated (780uL/L), under which wheat was grown and used to feed the larva. The results of this study showed that there was not a significant difference in larval mortality between two treatments, though it was slightly higher at elevated than ambient CO2.Measurement of three protective enzymes—SOD, GSH-PX and CAT in the6th instar larva showed that activity of SOD and GSH-PX decreased at elevated CO2as opposed to that at ambient CO2.Adult body dry weight was not impacted by the CO2treament. Water content and and muscle dry weight in female body was significantly lower than those in male’s. Triglyceride contents were significantly lower under ambient than elevated CO2. The CO2treatment had a certain impact on the glycogen content. The results if this study suggested that migratory M. separate may decrease in flight ability under climate change.2. Proj etion of potential distribution of Mythimna separate under rising temperatureM. separate occurs in most parts of China except Xinjiang and Tibet. When temperature is rising, low suitable areas of population growth index are increased. moderately suitable area of population growth index is increased too. While highly suitable area decreases. In summary, suitable time for the growth of M. separate in our country overall trend towards shorter. When temperature rises, generations of M. separate in one year will increase one. The area which occurrs more than six generations a year is significant increase. While the area which occur2-3generations shrink. M. separate can not survive on the north of33°N at winter. Suitable area at winter extended northward one latitude under highter temperature. South China become moderate suitable area from highly suitable area. When temperature is rising, low suitable areas largely increase, moderate suitable area slightly increase, highly suitable area decreases. M. separate annual migratory path may change. The highly suitable area most likely M. separate outbreak in case of meteorological factors such as airflow which is not conducive to move out.