Inheritance Characteristics Of Egg Diapause And Geographical Variation Of Life Cycle's Model In Oxya Chinensis Thunberg

This paper studied the inheritance characteristics of egg diapause and geographical variation of life cycle's model in Oxya chinensis Thunberg which collected from Tieling of Liaoning Province, Jining of Shandong Province, Sihong of Jiangsu Province. Changsha of Hunan Province and Haikou of Hainan Province from the following aspects:diapause intensity, inheritance characteristics of egg diapause and geographical variation of life cycle. The results were as follows:(1) The egg diapause rate of Tieling, Jining and Sihong populations were higher than the egg diapause rate of Changsha and Haikou populations. The period of beginning to hatch became longer with latitude decreased among Tieling, Jining and Sihong populations when hatching in the same condition. At the same time, the chilling of low temperature had obvious influence on the termination rate of five geographical diapause eggs.especially among Tieling, Jining and Sihong populations. These suggested that egg diapause showed obvious geographical variation in different populations.(2) The hatching rate of the hybrid offsprings among the five geographical populations were about 90% after chilling which indicated that there was no production isolation among different populations. In reciprocal crossings between Jining and Changsha, Sihong and Changsha or Tieling and Haikou populations, some eggs of offsprings were nondiapause which had the same characteristics with Changsha and Haikou populations. But no matter Changha and Haikou populations acted as maternity or paternity, the diapause rate of offsprings were higher than Changha and Haikou populations which were approximately to the Tieling, Jining and Sihong populations. These results suggested that the diapause occurrence was controlled by female and male gene, while the diapause extent was more close to the parent which had a higher diapause rate. We also got the conclusion that the grasshopper's egg diapause were controlled by multi-genetic from the selective test of Changsha populations.(3) Maternal photoperiodism had no influence on egg diapause rate of Tieling, Jining, Sihong and Changsha populations, while it had obvious influence on egg diapause rate of Haikou populations. Tieling, Jining and Sihong populations were univoltine while Haikou populations were bivoltine. Changsha populations were also partially bivoltinc from its result of egg diapause rate, the frequency distribution of head width and the amount of laying eggs.Nondiapause eggs of Changsha populations even could overwinter safely. This indicated that the evolution of diapause egg was not to avoid the low temperature of winter, but to synchronize their life cycle with the changing season.