The Research On Characters Of Biology And Embryonic Development In Rammeacris Kiangsu Tsai

This paper studied five geographical populations of Rammeacris kiangsu Tsai which collected from Yongchang of Chongqing Province, Changning of Sichuan Province, Taojiang of Hunan Province,Guilin of Guangxi Province and Guangning of Guangdong Province from biological characteristics, egg diapause, embryonic development and so on. The study results are as follows:(1) All the male nympha of five geographical populations of Rammeacris kiangsu Tsai are 5 instar, but the female nympha are partly 5 instar and partly 6 instar. Its development period of female nymph is longer than the male nymph but it does not exists significant differences among the five geographical populations.1,2 and 3 instar of nymph development periods of male and female are significantly shorter than of the 4,5,6 instar. The body size (head width, femur length of hind leg) of nymph and adult of five geographical populations does not exist significant difference either which suggests that there is no significant geographical variation among different geographical populations in Rammeacris kiangsu Tsai.(2) The diapause rate of five geographical populations'egg of Rammeacris kiangsu Tsai are 100% under the constant temperature condition of 20℃,25℃,30℃. The egg stage is shortened with the rising of temperature which shows that the hatching temperature influences egg hatching of Rammeacris kiangsu Tsai obviously. Chilling of 30 days under the condition of low temperature doesn't show obvious influence on the termination rate of five geographical populations'diapausing eggs (the hatching rate of Yongchang, Changning and Guangning are 0, Taojiang and Guiling are 0.8%,10.1% respectively), but chilling of 60 days and 90 days can obviously enhance the hatching rate of five populations.It means that low-temperature(8℃) has clear influence on diapause termination and the more longer of the time of low-temperature treatment, the more obvious of its effect on diapause termination. It needs more than 90 days chilling to eliminate egg diapause competely. But the experienced photoperiod and temperature of maternal generation doesn't have remarkable difference on the rate of egg diapause.(3) The study of Rammeacris kiangsu Tsai of Taojiang population shows the embryonic development may divide into 10 stages, and the blastokinesis mainly occurs in 45-75d in.The water content of eggs which are just oviposited is the lowest which is approximately 44%. Then the egg absorbs water quickly and the speed of absorption water relatively slow after 40 days. The water content will reach about 70% before hatching.Fresh mass of eggs increase with increasing of its water content. Biomass of eggs reduce with the embryonic development which making nutrient are oxidated and consumed.The embryonic development is relatively slow in the egg stage of 40-75 days, but the super-cooling point of egg is lower in the middle peperiod (20-60d) than the early (1d-15d) and the later period (after 70d). These results indicate that the egg diapause of Rammeacris kiangsu Tsai doesn't stop growth completely but relatively slow;The egg is in the diapasue state during the period of 20-75days after laying down, and the intensity of egg diapasue is the deepest during the period of 40-60days under the constant temperature condition of 25℃.