As a result of nitrogen uptake from chitin and protein (BSA), leaf
N content significantly increased in comparison with the control
plants (Table 1). The decrease of the foliar N content in control
plants in comparison to the plants at the beginning of the experiment
indicates that the prey-deprived plants were nutrientstressed and they were not able to maintain a higher foliar N
content (Table 1). The shoots of chitin-fed D. capensis plants
showed significantly more negative d15N values than the unfed
plants or plants at the beginning of the experiment (Fig. 1). Given
the d15N value of chitin (d15N ¼ 4.560‰), we estimated that
D. capensis derived on average 49% of the shoot N from chitin. By
comparing the N content in the chitin before and after digestion, it
was found that 93% of the nitrogenwas still in the undigested chitin
and only 7% was absorbed.