Woods H A
Department of Zoology, University of Washington, Seattle, WA, 98195, USA.
Physiol Biochem Zool. 1999 Jul-Aug;72(4):445-54. doi: 10.1086/316678.
For many insect herbivores, variation in protein availability is a pervasive part of the environment. I explore how variable protein availability affects growth rates of fifth-instar Manduca sexta caterpillars and how growth is related to behavior and physiology. Groups of larvae were reared on low- or high-protein artificial diets (5.9% and 17.7% casein by dry weight, respectively) and then transferred in the fifth instar to the same or opposite diet. During or after the 24-h period following transfer, I measured growth rate, consumption rate, growth efficiency, midgut proteolytic activity, and masses of midgut contents and tissues. Fifth-instar caterpillars reared in earlier instars on high-protein diet grew about 20% more rapidly over 24 h than did caterpillars reared on low-protein diet. This growth pattern appears to be caused by differences in consumption and growth efficiency: caterpillars reared on high protein consumed more food, and used it more efficiently, than did caterpillars reared on low-protein diet. Over the short term (24 h), in contrast, fifth instars that received low-protein diet grew as rapidly as caterpillars that received high-protein diet. Increased (compensatory) consumption appears to be the primary mechanism by which caterpillars consuming low-protein food maintained growth rates.
对于许多食草昆虫而言，蛋白质可利用性的变化是其生存环境中普遍存在的一部分。我探究了蛋白质可利用性的变化如何影响烟草天蛾五龄幼虫的生长速率，以及生长与行为和生理之间的关系。将幼虫分组饲养在低蛋白或高蛋白人工饲料上（干重分别含5.9%和17.7%的酪蛋白），然后在五龄时转移到相同或相反的饲料上。在转移后的24小时期间内或之后，我测量了生长速率、消耗速率、生长效率、中肠蛋白水解活性以及中肠内容物和组织的质量。在早期龄期以高蛋白饲料饲养的五龄幼虫，在24小时内的生长速度比以低蛋白饲料饲养的幼虫快约20%。这种生长模式似乎是由消耗和生长效率的差异造成的：以高蛋白饲料饲养的幼虫比以低蛋白饲料饲养的幼虫消耗更多食物，且利用得更高效。相比之下，在短期内（24小时），接受低蛋白饲料的五龄幼虫与接受高蛋白饲料的幼虫生长速度一样快。摄入量增加（补偿性）似乎是食用低蛋白食物的幼虫维持生长速率的主要机制。
