A Pollen Diet Confers Ultraviolet-B Resistance in Phytoseiid Mites by Providing Antioxidants

Abstract

Many plant-dwelling mites including phytophagous spider mites and predacious phytoseiid mites suffer lethal deleterious effects from solar ultraviolet-B (UVB; 280-315 nm wavelength) radiation. Phytoseiid species also often feed on pollen as an alternative food source. As pollen is frequently exposed to solar radiation, it is likely to contain compounds that protect germ cells from UVB radiation and radiant heat. If phytoseiid mites can obtain these protective compounds, pollen feeding may play a role in their adaptation to UVB. In this study, we compared the potential protective effects of tea pollen, peach pollen, and Tetranychus urticae mites as food items in Neoseiulus californicus. Egg hatchability and adult female survival after UVB irradiation were higher in pollen-fed than mite-fed N. californicus. The major protective effects of peach pollen and tea pollen were UVB shielding effects and antioxidant capacity, respectively, and these were derived from distinctive antioxidant components. The major antioxidant in peach pollen was trip -coumaroylspermidine, although its antioxidant capacity was relatively low; instead, it effectively absorbed UVB radiation. By contrast, the major antioxidants of tea pollen were catechin and epicatechin 3-gallate, which had high antioxidant capacities. Our results indicate that the protective antioxidant components in pollen improved UVB resistance in N. californicus, contributing to their adaptation to solar radiation.

Biological impact of ultraviolet-B radiation on spider mites and its application in integrated pest management

“…Then, the UV-B tolerance of the eggs increases, reaching a maximum just prior to hatching (Murata and Osakabe 2014). Neoseiulus californicus eggs show their highest UV-B vulnerability at similar embryonic development periods as those of T. urticae eggs (Sugioka et al 2018). Interestingly, the goldfish Carassius auratus (L.) embryo shows a similar time course of sensitivity and resistance to UV-B as that of mites (Wiegand et al 2004).…”

“…Considering the reciprocity of UV-B-induced mortality (Murata and Osakabe 2013), the difference in vulnerability could be attributed to the shorter egg duration of phytoseiid mites relative to spider mites. Moreover, variations in UV-B vulnerability among the embryonic developmental stages (Murata and Osakabe 2014;Sugioka et al 2018;Yoshioka et al 2018) may be involved. This topic may be related to the interaction between UV damage and temperature and thus linked to the issue of global climate change.…”

“…The studies described above suggest the involvement of multiple factors, such as developmental stage and timing of gene expression. In spider mites, some stages are specifically vulnerable, such as developing embryo and quiescent juvenile Osakabe 2014, 2017b;Sugioka et al 2018;Yoshioka et al 2018). Research in the association of such stage-specific UV-B vulnerability with variation in the thermal dependence of UV damage will be worthwhile for elucidating adaptation to UV-B radiation in mites.…”

“…The germ cells contained in pollen must be protected from ambient UV-B, and therefore, pollen contains UV-B-protective compounds (Feng et al 2000;Wang et al 2010;Žilić et al 2014). Sugioka et al (2018) identified tri-coumaroylspermidine and catechins as the major antioxidants in peach pollen and tea pollen, respectively. Neoseiulus californicus females fed pollen showed increased survivorship after exposure to artificial UV-B irradiation, and the viability of eggs produced by pollen-fed females was higher than that of T. urticae-fed females (Sugioka et al 2018).…”

“…Sugioka et al (2018) identified tri-coumaroylspermidine and catechins as the major antioxidants in peach pollen and tea pollen, respectively. Neoseiulus californicus females fed pollen showed increased survivorship after exposure to artificial UV-B irradiation, and the viability of eggs produced by pollen-fed females was higher than that of T. urticae-fed females (Sugioka et al 2018). The transmission of those antioxidants into eggs has not been proven unfortunately.…”