| The increase of ultra-radiation caused by environment deterioration has become aworldwide environmental problem. Consequently, ultra-radiation, especially UV-B radiationhas a powerful stress on the genetic evolution of insect. The ecological genetics, evolutionand regulation of Sitobion avenae (Fabricius) exposed to UV-B radiation can be acknowle-dged byanalysing the effects of UV-B radiation for several successive generations on them.The effects and changing patterns of UV-B radiation on growth, development andreproduction and corresponding enzymic activities of Sitobion avenae (Fabricius) wereevaluated by establishing an age-specific life table of S. avenae exposed to UV-B radiationfor eight successive generations. What's more, the corresponding enzymic activities andprotein content of the first, the eighth and the eighteenth generations were also determined.The result indicated that:1.UV-B radiation has remarkable impact on the life table parameters of Sitobion avenae(Fabricius) partially: while the intrinsic rate of increase (rm), net reproductive rate (R0), finiteincrease rate (λ) of S. avenae exposed to the UV-B were decreased obviously from the firstgeneration to the third one, these paeameters then became stable in the following generations.With the increase of duration of exposure, the difference between treatment group and controlone was becoming remarkable gradually, which indicated that UV-B radiation seriouslyaffects the S. avenae.2. Effects of UV-B radiation on the development and reproduction of S. avenae: Underthe UV-B radiation, the longevity and fecundity decreased gradually with the increase ofgenerations at first, then kept stable, and the lowest point is the third generation. Thedevelopmental time of the second and the third instar nymphs of S. avenae were delayedunder the treatment of UV-B radiation, and the fecundity of S. avenae exposed to the UV-Bradiation was much lower than the normal S. avenae, while it was reversed in the seventhgeneration. It indicates that: the molting of nymphs was delayed because of UV-B radiation,as well as the developmental duration was increased, the shortening of adult longevity anddecreasing of fecundity could be also caused by UV-B radiation. However, the adaption of S.avenae to the UV-B radiation enhanced with the increase of generations. S. avenae of controlgroup presented degeneration with the increase of generations. 3. Effects of UV-B radiation on the wing-form of S. avenae: In the treatment group, theratio of winged aphids was different significantly from the control group. The tendency of S.avenae exposed to the UV-B radiation was accord with V type pattern, which was quitedifferent from the normal ones. It indicated that UV-B radiation played an important role onthe change of wing-form.4. Effects of UV-B radiation on the tendency of S. avenae population: population numbertendency index (I) of control group kept decreasing, while in the group radiated, it decreasedfrom the first generation to the third generation. Besides, the I of the group radiated washigher than the control group in the seventh generation. However, the significant difference ofI was not been found in the other generations. It indicated that the adaption of S. avenaeenhanced with the increasing intensity of the UV-B radiation.5.Effects of UV-B radiation on the enzymic activities: under the treatment of UV-Bradiation, the activity of SOD in S. avenae increased gradually and the differences becamemore obvious with the increase of generations. It was indicated that the enzymic activity ofSOD was notablely affected by UV-B radiation, The activity of POD in S. avenae decreasedwith the generation went on, while it increased in the control group. It indicated thatultra-radiation played an important role on the change of POD activity. Besides, the tendencyof increase for the CAT activity could be shown in the UV-B radiation group of S. avenae,and the differences was remarkable contrasted by the control group.6.Effects of UV-B radiation on the protein content in S. avenae: the differences of theprotein content among different treatments and generations were notable. It could be indicatedthat different effects of UV-B radiation on the protein content could be found in the differentgenerations of S. avenae. Differences between the radiated and the control were distinct,which indicated that the protein content of S. avenae could be seriously affected by UV-Bradiation.In short, effects of UV-B radiation have involved in many aspects of S. avenae, such asthe ecological parameters, development and reproduction, wing-form, the activities ofenzymes and the content of protein. The oxidative stress-related enzyme played an importantrole in the process of protecting the development of S. avenae under the condition of UV-Bradiation. It indicated that S. avenae tended to adapt to the UV-B radiation. However, it is stillneeded to determined that if the related genes has been varied according to the successionalUV-B radiation. |
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