Abstract
Simple SummaryThe decrease of stratospheric ozone contributes to a significant increase in solar ultraviolet (UV-B) radiation. This effect has led to investigation on the impact of increased UV-B radiation on insect physiology. Pea aphid is a worldwide important agricultural pest and is difficult to control due to its small size, high fecundity, and non-sexual reproduction. As such, there is a need for study of the effects of UV-B radiation on aphid physiology, to raise awareness of the mechanisms of aphid responses to UV-B stress. The results reported here revealed that UV-B radiation can lead to an increase in sugar contents in both red and green morphs of this aphid species, and confirmed the effects of UV-B radiation on aphid physiology by means of influencing protective enzyme activity.Natural and anthropogenic changes have been altering many environmental factors. These include the amount of solar radiation reaching the Earth’s surface. However, the effects of solar radiation on insect physiology have received little attention. As a pest for agriculture and horticulture, aphids are one of the most difficult pest groups to control due to their small size, high fecundity, and non-sexual reproduction. Study of the effects of UV-B radiation on aphid physiology may provide alternative control strategies in pest management. In this study, we examined the effects of UV-B radiation on protein and sugar contents, as well as the activities of protective enzymes, of the red and green morphs of the pea aphid over eight generations. The results indicated a significant interaction between UV-B radiation and aphid generations. Exposure of the pea aphids to UV-B radiation caused a significant decrease in the protein content and a significant increase in the glycogen and trehalose contents at each generation as measured in whole aphid bioassays. The enzyme activity of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) of the pea aphids changed significantly at each generation with UV-B treatments. The SOD activity increased over eight generations to the highest level at G7 generation. However, the enzyme activity of CAT first increased and then decreased with UV-B treatments, and POD mostly gradually decreased over the eight generations. Therefore, UV-B radiation is an environmental factor that could result in physiological changes of the pea aphid. Moreover, our study discovered that red and green aphids did not display a significant consistent difference in the response to the UV-B treatments. These results may prove useful in future studies especially for assessing their significance in the adaptation and management against UV-B radiation.
Highlights
IntroductionThe decrease of stratospheric ozone makes solar ultraviolet (UV-B) radiation increase significantly [1], and has great and sometimes adverse effects on the carbon and nitrogen cycle of the whole biosphere [2], living habitat [3], biological characteristics [4], physiology, and biochemistry [5], and this is likely to affect aphids.In recent years, the destruction of the stratospheric ozone layer in the Earth’s atmosphere by the emission of anthropogenically generated pollutants [6,7] has greatly increased interest in the effects of solar ultraviolet radiation, especially ultraviolet-B (UV-B)radiation, which is considerably more harmful to living organisms than UV-A because of its shorter wavelength and higher energy levels [8]
We used one-way ANOVA and Tukey’s honestly significant difference (HSD) test to separately compare the effect of UV-B treatment at G0 –G7 generation and the effect of growth generation under different UV-B treatment
The current study reports the long-term effects and possible mechanisms of UV-B on the protective enzyme activity and nutritional dynamics of the red and green morphs of pea aphids over eight generations
Summary
The decrease of stratospheric ozone makes solar ultraviolet (UV-B) radiation increase significantly [1], and has great and sometimes adverse effects on the carbon and nitrogen cycle of the whole biosphere [2], living habitat [3], biological characteristics [4], physiology, and biochemistry [5], and this is likely to affect aphids.In recent years, the destruction of the stratospheric ozone layer in the Earth’s atmosphere by the emission of anthropogenically generated pollutants [6,7] has greatly increased interest in the effects of solar ultraviolet radiation, especially ultraviolet-B (UV-B)radiation, which is considerably more harmful to living organisms than UV-A because of its shorter wavelength and higher energy levels [8]. The decrease of stratospheric ozone makes solar ultraviolet (UV-B) radiation increase significantly [1], and has great and sometimes adverse effects on the carbon and nitrogen cycle of the whole biosphere [2], living habitat [3], biological characteristics [4], physiology, and biochemistry [5], and this is likely to affect aphids. There is a consensus that gradual UV-B radiation intensity can result in serious climate change, including increase in global temperature, imbalances in natural ecosystems, and risks for the survival of living organisms [7]. It is considered to be an environmental factor that induces oxidative damages to organisms through the production of reactive oxygen species (ROS), and causes damage to DNA, membrane lipids, and proteins [10,11,12,13,14]. Information about oxidative stress induced by UV irradiation in insects is scarce, including for aphids, and relatively few studies have examined the responses of protective enzymes in insects under UV irradiation
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