Effects Of UV-B Radiation On The Life Table Parameters And Feeding Behavior Of Sitobion Avenae(Hemiptera:Aphididae)

The atmospheric ozone layer is becoming thinner due to the environmental pollution, and the destruction of the ozone layer leads to a large number of ultraviolet radiation to the surface, high intensity ultraviolet stress has a strong selective pressure on insects. To evaluate the UV-B radiation on the growth, development, reproduction and feeding behavior of wheat aphid S.avenae, through using different intensity and different duration of UV-B on S.avenae, with making the life table of S.avenae in each treatment, and with the aid of Electrical penetration graph(EPG) technology, then to explore the effect of different intensity and different duration of UV-B on S.avenae. The results are the followings:1. Effects of UV-B radiation intensity and duration on the growth, development and fecundity of S.avenae(1) Changes of life table population parameters of S.avenaeAfter different intensity and different duration of UV-B treatments, both the two factors had significant effects on the population parameters: the intrinsic rates(r), net reproductive rates(R0) and the finite rates(λ), and there was a significant interaction between the two factors. Under the same duration but different intensity of the UV-B radiation treatments, in 9 h and 15 h treatment groups, the r, R0 and λ decreased with the increased intensity of UV-B, and were all significantly lower than the control treatment(no UV-B radiation). In 3 h treatment, r, R0 and λ were significant lower than the control treatment under the high intensity of UV-B(0.75 mW/cm2). Changes of the S.avenae population ecology parameters under different treatments indicated that the change of intensity and duration of UV-B cound affect S.avenae growth and reproduction, and with the higher intensity or longer duration of UV-B wound increase its negative effects.(2) Changes of mean relative growth rates(MRGR) and fecundity parameters of S.avenaeIn the different UV-B treatments, compared to control group, there were little changes of the MRGR, only when in high intensity and prolonged UV-B treatments generated a significant difference, and were lower than the control group. Under the same duration treatments, fecundity(F) decreased significantly with the increased UV-B intensity, the similar effect of UV-B occurred when increased the duration of UV-B under the same intensity. Reproduction days and longevity of adult S.avenae were also affected by the UV-B radiation, the reproduction days and longevity of adult aphid decreased with the higher intensity or longer duration of UV-B, they were more remarkable in the high intensity(0.75 mW/cm2) and long term duration(15 h) treatments. The aphid in the UV treatments had a higher proportion of alataes than the control group, and there was a rising trend with the increased radiation intensity and duration of UV-B.2. Effects of different intensity of UV-B radiation on the feeding behavior of S.avenaeCompared to the aphids which feed with no UV-B radiation, the total duration of non-probing waveforms(np) and pathway phase waveforms(C) of S.avenae showed significant increase, and prolonged with the increasing intensity, the occurrence of np and C waveforms were also increased with the higher UV-B intensity. The phloem feeding activities include sieve-element salivation(waveform E1) and phloem ingestion(waveform E2), both the total duration showed significant decrease with the increasing UV-B intensity, the occurrence of E2 waveforms were also decreased with the higher UV-B intensity. The total duration of xylem ingestion waveforms(G) were not significantly different among the treatments.To summarize, through the control of different ultraviolet radiation intensity and different duration, UV-B can reduce population growth, development and reproduction parameters of S.avenae, aggravating with the higher intensity or longer duration of UV-B, and there was a significant interaction between the two factors. The feeding behaviors of S.avenae were significant influenced by the high UV-B intensity, with decreasing the feeding ability of S.avenae.