Japanese oak silkmoth feeding preference for and performance on upper-crown and lower-crown leaves.

摘要

We quantified differences in leaf traits between upper and lower crowns of a deciduous oak, Quercus acutissima, and examined feeding preference, consumption and performance of the Japanese oak silkmoth, Antheraea yamamai, for those leaves. Upper-crown leaves had significantly smaller area, larger dry mass per area, greater thickness, lower water content, higher nitrogen content and a higher N/C ratio than lower-crown leaves. When simultaneously offered upper-crown and lower-crown leaves, moth larvae consumed a significantly larger amount of the former. However, when fed with either upper-crown or lower-crown leaves (no choice), they consumed a significantly larger amount of the latter. Female larvae reared on upper-crown leaves had a significantly smaller fresh weight, but attained a significantly larger pupal fresh and dry weight, with a significantly higher relative growth rate than those on lower-crown leaves. Although, like female larvae, male larvae had a significantly smaller fresh weight when reared on upper-crown leaves, they had a significantly larger value only for pupal dry weight. These results suggest that: (i) larvae ingest a greater amount of lower-crown leaves to compensate for the lower nitrogen content of the foliage, resulting in having an excess of water because of the higher water content of the foliage; (ii) feeding preference for upper-crown leaves accords with better performance (with respect to dry pupal weight and relative growth rate) on the foliage; (iii) better performance is explained by a higher nitrogen content and N/C ratio of the upper-crown foliage; and (iv) the effects of leaf quality on performance differ between sexes..