Terrestrial animals are widely considered to be well protected from damage caused by ambient UV radiation, and thus the direct effects of solar UV-B radiation on arthropods have not attracted a great deal of attention. However, if plant-dwelling arthropods have evolved behavioral adaptations to solar UV-B radiation, but not morphological or physiological adaptations, the resources available to them would be strongly limited. Tetranychus urticae and their dominant natural enemies, phytoseiid mites, usually stay on the lower leaf surfaces. Because of the accumulation of UV-B-absorbing compounds such as flavonoids in the leaves, the upper and lower leaf surfaces provide different UV environments. We tested whether UV irradiation affects survival and reproduction of T. urticae and, if so, whether staying on the lower leaf surfaces is beneficial for their performance in solar UV radiation. Consequently, we observed lethal effects of artificial UV-B irradiation and solar UV radiation on T. urticae. However, by remaining on lower leaf surfaces, the mites could avoid such deleterious effects. These suggest that staying on the lower leaf surfaces is a behavioral adaptation of T. urticae to avoiding harmful solar UV-B radiation. Lethal effects of UV-B irradiation also exerted strong deterrent effects on the hatchability of phytoseiid mites. Additionally, preliminary experiments suggested that phytoseiid mites avoided and quickly escaped from a place irradiated by solar UV. Therefore, solar UV-B radiation may strongly affect the diurnal and spatial patterns of distribution or migration of mite communities on host plant canopies.

This study has carried out to evaluate the effect of NaCl as electrolyte of single (electrolysis and UV process) and complex (electrolysis/UV) processes for the purpose of removal and mineralization of Rhodamine B (RhB) dye in water. It also evaluated the synergetic effect on the combination of electrolysis and UV process. The experimental results showed that RhB removal of UV process was decreased with increase of NaCl, while RhB removal of electrolysis and electrolysis/UV process was increased with increase of NaCl. The decolorization rate of the RhB solution in every process was more rapid than the mineralization rate identified by COD removal. The latter took longer time for further oxidation. Absorption spectra of an aqueous solution containing RhB showed a continued diminution of the RhB concentration in the bulk solution: concomitantly, no new absorption peaks appeared. This confirmed the decolorization of RhB, i.e., the breakup of the chromophores. It was observed that RhB removal in electrolysis/UV process is similar to the sum of the UV and electrolysis. However, it was found that the COD of RhB could be degraded more efficiently by the electrolysis/UV process than the sum of the two individual process. A synergetic effect was demonstrated in electrolysis/UV process.

In the present study we studied the growth, photosynthetic traits and protective mechanisms against oxidative stress in the primary loaves of cucumber (Cucumis sativus L.) seedlings with or without UV-B treatment. Cucumber seedings were irradiated with UV-B for 10 days in environment-controlled growth chambers. The primary leaves irradiated with UV-B showed reduction in leaf length and decreased biomass production. The reduced biomass production seemed to be due to a negative effect of UV-B radiation on the photosynthetic process. Changes in chemical properties of leaf, such as chi a/b ratio affected photosynthesis. UV-B significantly affected chl b content compared with chi a in the light harvesting complex resulting reduced photosynthetic activity Fv/Fm decreased with an UV-B stress, suggesting that the photosynthetic apparatus, and particularly, PS II was damaged under UV-B stress. Malondialdehyde(MDA) concentration which represents the state of membrane lipid peroxidation Increased significantly under UV-B stress confirming an oxidative stress. UV-B exposure with SA solution(0.1-1.0 mM) can partially ameliorated some of the detrimental effects of UV-B stress. Leaf injuries including loss of chlorophyll and decreased ratio of Fv/Fm were reduced with combined application of UV-B and SA. ABA and JA showed similar mode of action in physiological effects on photosynthetic activities though the levels were lower than those from SA treated plants. Chloroplast ultrastructure was also affected by UV-B exposure. The thickness of leaf tissue components decreased and the number of grana and thylakoids was reduced in chloroplast applied UV-B or SA alone. At combined stress granal and stromal thylakoids were less affected. The leaves under combined stress acquired a significant tolerance to oxidative stress. From these results, it can be suggested that SA may have involved a protective role against UV-B induced oxidative damage.