Seasonal Dynamics On Juvenile Hormone And Vitellogenin Expression During Migration In Noctuidae Insects

Many Noctuid insect are important agricultural pests, which became serious damage to agricultural production. Seasonal migration of insects is the adaptation to the habitat during the long process of evolution. Through long distance migration, the insects escape from the unfavorable environment by a ’there now’ strategy. Migratory pests were often caused sudden outbreaks in different areas. The facultative migratory of Helicoverpa armigera, the obligate migratory of Mythimn separata and Agrotis ypsilon were selected to analysis the seasonal migration dynamics, relationship between migration and reproduction biology, JH titer and related genes belong to JH, vitellogenin expression, the mainly results as follows:The JH titer was low in newly emergence adults and increasing to peak in3d female and2d male moths. The expression of HaJhamt, HaJheh and HaJhe were quite difference in different daily adults. Significance effect was found on the adult nutritional supplement, however, the expression of HaJhe and HaJheh was in opposite trend. Mating experience down-regulates the expression of HaJheh in Male, up-regulate the expression of HaJhe in both male and female. Seasonal dynamics of JH titer in both male and female of H. armigera, which shown same consistent treads in2years analysis, as JH titer increasing from early summer to late autumn. The key genes related to JH synthesis and degradation expression consistent to JH titer, such as up-regulation of HaJhamt in September and October, however, down-regulation of HaJheh and HaJhe in degradation in autumn. The expression of Havg was relatively low in1d female, increasing to top level in3d and was then dropped. Adult nutritional supplement and mating experience had no significant effect on Havg expression. The expression level of Havg in seasonal migratory decreased with the seasons; Havg expression levels from August to October were significantly lower than the in June. The expression model of Havg in seasonal migratory adults showed highly consistent accordance to the seasonal dynamics of ovarian development index and mating performance.Based on RT-PCR and RACE, the key genes in JH synthesis and degradation of JHAMT, JHEH, JHE, and Vg were cloned. The molecular characteristics, structure and evolution was determined. The3D homology modelling of JHAMT, JHEH and JHE was conducted, which lay the structural basis for the further studies on JH synthesis and metabolism pathways. The expression results showed that in A. ypsilon, no significance on the expression of AyJhamt in adults during the migratory season. Quite difference were found on the expression of AyJhehl, AyJheh2and AyJhe in adults, however, there were lack of seasonal tread. The expression of MsJhamt、MsJheh and MsJhe in mRNA levels in M. separata during the migratory season were also quite different, and without seasonal tread. There are individual differences on JH titer in male and female adults of the captured migration cutworm, however, seasonal variation was not significant fluctuations, and the average level of JH titer during the migratory season was relatively stable at a low level of11-14ng/mg. In the armyworm, the seasonal dynamics of JH titer shown the same trade, and the JH titer was around12-16ng/mg during the yearly migratory season. The expression level of Vg in both armyworm and cutworm showed the similar trends, as the relatively higher expression in May, highest in June, and were then decreasing step by step to the lowest in mid-Autumn. The expression model of Vg in adults of both armyworm and cutworm showed highly consistent accordance with the seasonal dynamics of ovarian developmental index and mating performance. Therefore, there were highly correlated related between the Vg expression and the ovarian developmental index in the obligate migration moths of both armyworm and cutworm.The results may reveal that between the facultative migratory of H. armigera, and the obligate migratory of M. separata, A. ypsilon, the regulating mechanism of JH on adults reproduction biological characteristics should be quite different. JH shown a mutual feedback regulating model on Vg expression, ovarian developmental index and mating performance during the seasonal facultative migratory of H. armigera, however, these were not fully shown in obligate migratory moth of M. separata and A. ypsilon. In fact, the reproduction biology in the facultative seasonal migratory H. armigera was more flexible and complex. In which, long distance migration may induce the increasing of JH titer, and which were then accelerate the development of ovarian. Therefore, there were mutual feedbacks regulating models in facultative migratory adults. However, in the obligate migratory adults of armyworm and cutworm, without seasonal treads in the expression level of key genes in JH synthesis and degradation metabolism, the average of JH titer remained at low level. And no significant correlations between the lower levels of JH titer and seasonal reproductive biological was found, which shown by ovarian development index and mating performance. Therefore, the function of JH in regulating the reproductive biology during the obligate seasonal long distance migration should be on a secondary role.