FOOD AND WATER ECONOMY AND ITS RELATION TO GROWTH IN 5TH-INSTAR LARVAE OF THE TOBACCO HORNWORM, MANDUCA-SEXTA
FOOD AND WATER ECONOMY AND ITS RELATION TO GROWTH IN 5TH-INSTAR LARVAE OF THE TOBACCO HORNWORM, MANDUCA-SEXTA
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DOI：
10.1016/0022-1910(85)90016-2
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发表时间：
1985-01-01
影响因子：
2.2
通讯作者：
STEPHENS, AE
中科院分区：
文献类型：
--
作者：
REYNOLDS, SE;NOTTINGHAM, SF;STEPHENS, AE
在25℃下用人工饲料饲养M. sexta的五龄幼虫。 C. 每日测量昆虫的湿重和干重、吃的食物和产生的粪便，以便为粮食和水经济制定详细的预算。近似消化率（AD）为.apprx。干重和能量均为 60%。尽管在同一时期昆虫的大小和摄食量发生了非常大的变化，但在龄期的连续几天中，这种情况并没有显着变化。在此期间，两个转换效率指数（ECI 和 ECD）也仅显示出微不足道的变化。 ECI 和 ECD 都非常高：处于最大值。 ECI 为 43%（以能源计算为 51%），ECD 为 72%（以能源计算为 81%）。在所有情况下，对肠道中食物存在的营养指数进行校正都会略微降低其价值。幼虫对水的大部分需求由饮食提供。代谢水的估计增益占总水输入的 3.5-10%。粪便占了体内流失的大部分水分；在一种条件下，蒸腾损失非常小。食物中吸收的水分几乎有一半被保留在体内。肠道内容物比食物的水分含量更高。粪便中的水分少于肠道内容物。毛毛虫可能通过从粪便中吸收水并将其返回到中肠内容物来循环利用水。提出了体内这种水运动的定量模型。这些数据提供了间接证据，表明毛毛虫可以优化食物在肠道（以及 AD）中的保留时间，以最大限度地提高营养吸收的绝对率。
Fifth-instar larvae of M. sexta were reared on artificial diet at 25.degree. C. Daily measurement of the wet and dry weights of insects, food eaten and feces produced, allowed the construction of detailed budgets for food and water economy. Approximate digestibility (AD) was .apprx. 60% both in dry weight and energetic terms. This did not change significantly on successive days of the instar, despite the very considerable changes that occur in the size of the insect and the amount of food eaten during the same period. Two indices of conversion efficiency (ECI and ECD) also showed only insignificant changes during this time. ECI and ECD were both very high: at their maximal values. ECI was 43% (51% in energy terms) and ECD was 72% (81% in energy terms). Correction of the nutritional indices for the presence of food in the gut reduced their value slightly in all cases. Most of the water requirements of the larva were provided by the diet. The estimated gain from metabolic water was between 3.5-10% of the total water input. Feces accounted for most of the water lost from the body; under one conditions transpirational losses were very small. Almost half of the water taken up with the food was retained in the body. The gut contents are more hydrated than the food. The feces contain less water than the gut contents. The caterpillars probably recycle water by absorbing it from the feces and returning it to the contents of the midgut. A quantitative model of such water movement within the body is presented. The data provide indirect evidence that caterpillars may optimize the retention time of food in the gut (and thus the AD) in order to maximize the absolute rate of nutrient uptake from it.