Effect of cocooning conditions on the structure, carbon and nitrogen isotope ratios of silks

Abstract

The stable isotope technique provides the possibility to trace ancient textiles because the technique is associated with advantages such as trace indication, fast detection, and accurate results. Since different cocooning conditions may impact cocoons even under identical habitats, it is important to investigate the effects of different cocooning temperatures and humidity on the isotope incorporation values in the cocoons. In this study, silk fibers were reeled under different conditions of temperature and humidity, followed by analysis of the secondary structure of cocoon proteins and isotope incorporation patterns. We found that the deviations in carbon isotope values of silk under different cocooning conditions could reach up to 0.76‰, while the deviation in carbon isotope values at different locations of a single silk was 2.75‰. Further, during the cocooning process, depletion of the 13C-isotope at different locations of the silk fibers was observed, reducing the δ13C values. We proposed that the changes in carbon isotopes in silk were related to the content of sericin and silk fibroin in silk. Finally, we did not observe a significant difference in isotope ratios in degummed cocoons. In summary, the 13C isotope was enriched in sericin, whereas 15N was enriched in fibroin, and these findings provide basic information for tracing the provenance of silks.

Distribution patterns of Phytoseiulus persimilis in response to climate change

“…Differed from P. persimilis, maximum temperature in November (tmax11) and the precipitation of the coldest quarter were the most critical variables for N. californicus and N. cucumeris, respectively. 45,46,60 Precipitation of the coldest quarter was found to be important for all these species, but with much more influence on P. persimilis. A plausible explanation is that it is more sensitive to humidity than the other two predator species.…”

“…Among a wide variety of the abiotic factors, temperature and humidity were the most critical environmental factors for many species. [43][44][45]47 According to the prediction, the minimum temperature of the coldest month is the first and foremost critical bioclimatic variable determining the distribution of the predatory mite, indicating that the extreme temperature in winter is crucial for this species. These findings align with a prevailing hypothesis that climatic extremes, rather than averages, exert more substantial constraints on biota.…”

“…58 In recent years, the MaxEnt model has been also employed to evaluate the potential distribution of other predatory mite species, such as Neoseiulus californicus and Neoseiulus cucumeris. 45,46,59,60 Although these three species were all predators of spider mite T. urticae, the dominant climatic variable for their distribution model and their contribution rate varied. Differed from P. persimilis, maximum temperature in November (tmax11) and the precipitation of the coldest quarter were the most critical variables for N. californicus and N. cucumeris, respectively.…”