Quantifying Food Consumption and Growth in Insects

Relative consumption rate is frequently calculated as weight of food consumed divided by mean body weight over the course of the feeding period. However, mean weight incorporates weight change, which is a function of digestive efficiency; relative consumption rate, therefore, is inherently dependent on physiological responses. In short-term (within one instar) experiments quantifying insect behavior, the maximum amount of food an insect can eat is not likely to vary directly with body weight. Under such circumstances, it is more appropriate to relate consumption to the weight of the insect at the beginning of the test, not to mean weight. The use of mean weights produces a similar bias in relative growth rate.