The Effect of intermittent Starvation upon the Development of Larvae of the Meadow Moth (Loxostege sticticalis, L.)

Abstract

1. When studying the effect of intermittent starvation upon the length of development of the larval phase it is necessary to carry out experiments with each stage separately. Ignoring this factor and carrying out experiments on the larval phase as a whole results in serious errors.2. The shorter the periods of feeding and consequently the longer starvation periods during each 24 hours the stronger their effect upon the length of development of each stage.3. More than 50 per cent. of larvae fed only for 2 hours a day and starved for 22 hours accomplish their complete metamorphosis and produce moths that are fully capable of living.4. The length of development of each stage depends upon the feeding regime during the previous stage. Using the same starving regime, development of the last stage is the longer the earlier the stage at which larvae were subjected to this regime.5. At different stages of development larvae react differently to the same starvation regime. Thus starving for 12 hours a day increases the duration of the development of the 3rd stage by 104 per cent. ; that of the 4th stage does not increase at all, while the development of the 5th stage increases only by 31 per cent.6. Nature of food greatly influences the length of development under conditions of intermittent starvation. Starving for 8 hours a day when feeding larvae on wormwood results in greater increase of development than starving for 12 hours a day when feeding on goose-foot.7. All factors influencing the development of the larval phase result in decreasing the weight of the pupae. Decrease in weight of pupae is the greater the longer the starvation periods and the earlier larvae were subjected to starvation effect. Nature of food also highly affects the weight of pupae.8. Intensity of feeding during feeding periods of starving larvae does not decrease as compared to control. With very strongly starving larvae intensiveness of feeding even increases.9. There is no direct proportion between the quantity of excrement passed, that is amount of food consumed and the weight of pupae. The longer the development, the more there are feeding periods and consequently the more excrement passed. Owing to the lengthening of development the most part of substances consumed are spent on vegetative functions ; therefore there cannot exist direct connection between the number of excrement passed and the weight of pupae.