Introduction
Foraging Behavior is an important mechanism used by Drosophila for feeding. This behavior is associated to the for gene, particularly to the alleles related to the rover and sitter, named forR and forS, respectively. The presence of these alleles in Drosophila is related to food behavior (Kent et al., 2009).
D. melanogaster is an insect known as the fruit fly and it has been used in different studies, including those related to sensory systems, such as hunger and diet selection (Schwarz et al., 2013). Their preferred food is rotting fruits, particularly those having sugars and amino acids, being carbohydrates the major source of food in adult individuals (Thorne et al., 2014).
Yeasts and sucrose provide many nutrients to flies. When flies are deprived of amino acids, they prefer to ingest yeast instead of sugar. In contrast, when they are deprived of sugar, they prefer sucrose instead of sugar (Piper et al., 2014).
This investigation will focus on the determination of Drosophila melanogaster feeding selection behavior between yeast and sucrose. The related question is “Do hungry fruit flies prefer yeast solution or sucrose solution?” Furthermore, this investigation will use the null hypothesis that no significant difference is found between the observed and expected results for yeast and sucrose feeding preference in fruit flies, particularly in Drosophila melanogaster.
Results
Data is shown on Table 1. At 30 min, the highest quantity of flies was reported for the yeast solution (50), similar to fly quantities reported for sucrose (42). On the other hand, at 60 minutes, the experiment quantities for sucrose solution and yeast solution were very different, being 76 and 20 flies, respectively. Significant difference (p<0.001), was found when the chi-squared test was applied for 30 min and 60 min observations. Calculated chi-squared and p is presented in Table 1. A high quantity of not fed flies (96) was observed at 30 min, yet they reduced considerably (24) at 60 min.
Discussion
Foraging Drosophila localize the food using the chemoreceptors. They feed on bacteria and fungi present or rotting fruit (Aracena, 2011). The main components of the media prepared in laboratory to cultivate Drosophila contain a source of sugar, yeast and agar. Variation in quantities of flies was found during the time of the experiment, reflecting the preference of flies for each substrate. At the beginning, most of the flies did not feed, and had little preference for the yeast solution. This small difference between yeast and sucrose could be related to the adaptation of flies to the different substrates. At 60 minutes, the end of the experiment, most of the flies fed with sucrose solution. This means that flies prefer sucrose solution instead of yeast or both. Sucrose is a carbohydrate and when Drosophila detects sweetness, they associate it with the presence of sugar and caloric source from a substrate (Burke and Wadell, 2012). Sucrose is also a good source of nutrients for Drosophila, and a relation between memory and nutrient presence (Burke and Waddell, 2012) can influence in the preference of sucrose over yeast. This experiment shows the preference of sucrose over yeast by hungry Drosophila, rejecting the null hypothesis, since a significant difference was found (p<0.001). More experiments related to the feeding behavior in Drosophila are important because they can be related to human feeding behavior, especially because they are related through gene homology.
References
Aracena J. (2011) Using Foraging Behavior of Fruit Flies to Introduce Undergraduates to Research. Tested Studies for Laboratory Teaching Proceedings of the Association for Biology Laboratory Education. 32. 304-309.
Burke C. J. and Wadell S. (2012)Remembering nutrient quality of sugar in Drosophila.Current Biology. 21. 746-750.
Kent C. F., Daskalchuk T., Cook L., Sokolowski M. B. and Greenspan R. J. (2009) The Drosophila foraging Gene Mediates Adult Plasticity and Gene–Environment Interactions in Behaviour, Metabolites, and Gene Expression in Response to Food Deprivation. Public Library of Science. DOI: 10.1371/journal.pgen.1000609.
Piper M. D. W., Blanc E., Leitão-Gonçalves R., Yang M., He X., Linford N. J., Hoddinott M. P., Hopfen C., Soultoukis G. A., Niemeyer C., Kerr F., Pletcher S. D., Ribeiro C. and Partridge L. (2014) A holidic medium for Drosophila melanogaster.Nature Methods. 11. 100-105.
Schwarz S., Zachary D. and Dukas R. (2014) Food selection in larval fruit flies: dynamics and effects on larval development. Naturwissenschaften. 101. 61-68.
Thorne N., Chromey C., Bray S. and Amrein H. (2014) Taste Perception and Coding in Drosophila. Current Biology. 14. 1065-1079.
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