The Physiological And Genetic Characteristics Of Migratory Behavior And Genetic Diversity, As Determined By AFLP In The Oriental Armyworm, Mythimna Separata (Walker)

Since insect migration not only represents an adaptive syndrome in behavior evolved from adaptation to varying and unpredictable environmental conditions for long time, but also leads to serious damage of the crops, so the formation and regulation of insect migration and relationship between flight and reproduction and the physiological and genetic characteristics of migratory behavior are always the popular issue in the field of insect migration research. Recently most researches related physiological characteristics of insect migratory behavior are the result of analyzing laboratory insect populations and difficult to represent the fact of the natural populations, in addition, little is known about genetic characteristics and application of melecular biology to insect migratory behavior regulation, so this dissertation focus on the physiological and genetic characteristics in migration and genetic diversity of different geographical and melanic forms as determined by AFLP in Mythimna separata. The major progresses obtained from these studies are summarized as follows.Based on the migratory regulation of the Mythimna separata in china, emigrant and immigrant populations were trapped at the different time in Ganyu county Jiangsu province and Shengyang suburb Liaoning province. Characteristics and differences of the flight system between emigrant and immigrant populations were identified using flight balance system and physiological and biochemical methods, including flight potential, flight energy substrate and flight muscle. Meanwhile the reproduction system as female ovarian development and mating status and endocrine system as juvenile hormone were compared between populations using microanatomy and HPLC. In the emigrant populations, Moths exhibited stronger flight potential whose flight distance, total flight duration were 13.6 km, 153.1 min respectively, while were 6.0 km, 64.3 min in immigrant population, both of the flight potential variables were significantly less than those in emigrant population. Dry weight of the thoracic dorsal-longitudinal muscle in female was 6.53 mg and was significantly higher than the value of 5.92 mg in immigrant population. Although the content of triglyceride was significantly less than that in immigrant population, which was unexpected, most females exhibited little or no ovarian development and were seldom mated. Mean basal ovariole width, length, wet weight, mating rate and frequency were significantly lower than those in immigrant population. Third the female ovarian development and mating frequency were increased as increased with trapping time in the immigrant populations. Juvenile hormone titer (JH II) was 4.63 ng/mg and was also significantly lower than that of 8.69 in immigrant population. Comparison of most of these variables between the emigrant and immigrant populations suggests that there are obvious trade-off between flight and reproduction. The migrants have strong flight potential and reproduction activities are depressed before migration while begin mating and oviposition rapidly after they arrive at new habitats. The weight of flight muscle decreased significantly in the immigrantpopulations was the mainly evidence of resource from migration to reproduction. The juvenile hormone plays a significant roll in the trade-off between flight and reproduction in the female. This model fits the "oogenesis-flight syndrome" hypothesis well.It is well known that migratory behavior is regulated by many environmental and physiological factors such as rearing temperature, larval density, photoperiod, matting status, oviposition and hormone in Mythimna separata, while little is known affected by genetics. Genetic factors controlling flight and oviposition behavior in this species were quantitative analyzed based on the quantity genetics theory and methods. Including the narrow sense heritability of Pre-Oviposition Period (POP) and overall heritability and heritability due to paternal influence of flight distance and flight duration and selective response and chromos...