Abstract: 【Aim】 The objective of this research is to assess the effects of some snacks in the market on the weight and development of Drosophila melanogaster and then to explore the importance of nutrition balance in the diet for children. 【Methods】 The contents of proteins, fat and carbohydrates of the experimental snacks were detected by Biuret method, Sudan Ⅲ staining method, and iodine tincture staining method, respectively. Fruit flies were reared in the standard food (basal culture medium) or the foods made from the experimental snacks. Five days after egg hatching, the weight of the adults was measured and the midgut was dissected for immunofluorescence experiments. 【Results】 The contents of proteins, fat and carbohydrates in the basal culture medium of D. melanogaster were more balanced, while the experimental snacks were rich in only one kind of these components with imbalanced nutrients. Snacks with high contents of carbohydrates and fat caused fruit flies to be overweight. Meanwhile, theArm/Pros signal of the midgut cells increased significantly, indicating a great increase of stem cells. In addition, the wall of midgut was thickened. Foods lacking carbohydrates or proteins caused developmental disorders Foods with high content of carbohydrates but lacking proteins induced an increase of midgut stem cells, thickening of the midgut wall while loss of weight and slow development. At the same time, foods with high contents of proteins and fat but lacking carbohydrates caused decrease of stem cells, thinning of midgut wall and developmental disorder. For the fruit flies fed with the experimental snacks balanced according to the nutrient proportion of the basal culture medium, the midgut injury and the whole development were improved. 【Conclusion】 Imbalance of nutrition can significantly affect the individual weight, midgut wall and number of stem cells, and then lead to abnormal development in D. melanogaster. Intestinal disorder has a serious impact on its development. These results suggest that favoring snacks only can cause malnutrition, obesity and intestinal dysfunction to children, young children should not prefer snacks only, and the reasonable diet and balanced nutrition are important.

Key words: Drosophila melanogaster, snacks, nutrient balance, development, weight, midgut