Ohmart C P, Stewart L G, Thomas J R
CSIRO Division of Forest Research, Queen Victoria Terrace, P.O. Box 4008, 2600, ACT, Australia.
Oecologia. 1985 Mar;65(4):543-549. doi: 10.1007/BF00379670.
Five groups of E. blakelyi seedlings were differentially fertilized to obtain a range of N concentrations from 0.8-3.0% dry wt in the foliage. Groups of P. atomaria larvae were reared from eclosion to the prepupal stage on these seedlings. The effects on larval growth and development caused by foliar concentrations of N, moisture content, and tannins and leaf toughness were measured. Pupal dry weight and development time of P. atomaria did not differ between those reared on foliage with N levels of 1.7-3.0% but there was a significant decrease in pupal weight and increase in development time for individuals fed foliage with N below this level. Larvae fed foliage with an average of 0.8% N died before reaching instar III. Total dry matter consumption increased with a decrease in N concentration. Larval nitrogen utilization efficiency increased as foliar N level decreased until N reached a level somewhere between 1.7%-1.2% below which it decreased. There appeared to be an N concentration threshold above which P. atomaria larvae received adequate N by regulating consumption and nitrogen utilization efficiency but below which they could no longer accumulate enough N by compensation to maintain an optimum growth rate and development time. Effects of food quality variables on relative growth and consumption rates are presented and discussed.
将五组布莱克利伊桉树苗进行不同施肥处理，以使叶片中的氮浓度范围达到干重的0.8 - 3.0%。将粉斑螟幼虫从羽化饲养至预蛹阶段，以这些树苗为食。测定了叶片中氮浓度、含水量、单宁含量和叶片韧性对幼虫生长发育的影响。在氮含量为1.7 - 3.0%的叶片上饲养的粉斑螟，其蛹干重和发育时间没有差异，但对于取食氮含量低于该水平叶片的个体，蛹重显著降低，发育时间延长。取食平均含氮量为0.8%叶片的幼虫在进入三龄前死亡。总干物质消耗量随氮浓度降低而增加。随着叶片氮水平降低，幼虫氮利用效率增加，直到氮含量降至1.7% - 1.2%之间的某个水平，低于该水平后氮利用效率下降。似乎存在一个氮浓度阈值，高于该阈值时，粉斑螟幼虫通过调节消耗量和氮利用效率获得足够的氮，但低于该阈值时，它们无法再通过补偿积累足够的氮以维持最佳生长速率和发育时间。本文展示并讨论了食物质量变量对相对生长率和消耗率的影响。
