Data
Introduction: Fruit fly or Drosophila melanogaster is a small fly that measures about 3 mm long. The fly has several advantages that make it a preferred model in genetic studies. It has four pairs of chromosomes that codes for 16,000 genes (Jacob, 2012). The complete genome of the fly is sequenced and the information coded has been completely deciphered. In addition, fruit flies are easy to culture, have a short life cycle and easy to work with. The food preference in Drosophila is influenced by many factors and there are few studies that have explored this phenomenon. The olfactory and gustatory receptors are important in deciding the food preference of the fruit flies. These flies are useful models in studying the importance of chemosensory receptors of animals in finding food. Insects like Drosophila has the ability to evaluate their nutritional status and the environmental supplies, before modulating their food seeking behavior. There is no clear understanding on how this mechanism is regulated. The fruit flies are a useful model to study the genetic regulation of food preference for sugar, protein and lipid as well.
In this study, the food preference of Drosophila is studied. The Drosophila that feeds on sucrose were identified by the red color on their abdomen and those feeding on banana were identified by a blue color on the abdomen, as both these food items were stained with the respective food color. Drosophila has ~68 gustatory receptors that help it to select nutrients (Jacob, 2012). The gustatory receptor in the legs or proboscis helps the flies sense taste. In addition, the smell of the food and sensory clues received from other flies that feed together is all important for making eating decisions. Flavor helps the flies to differentiate between food that is good and harmful. Short term feeding decisions in flies are based on palatability, rather than nutritional content. Sucrose and banana are conventional food source for the flies are thus employed in this study.
Result:
Chi Square Test: The significance in the difference of food preference between plain sucrose and banana flavored sucrose was tested at 30 minutes and later phase using Chi-square test and the readings are as follows: Chi-square value 7.8767, p value = 0.005008. The result is significant at p < 0.005.
Discussion: Fruit flies are a pest in commercial enterprises and finding ways to attract them and trap them can help with pest control. Baits like banana mash with yeast have been used as attractants from the early 20th century. In Drosophila, taste plays an important role in early stage of food selection. Though there is a genetic preference for food and flavor, all strains of Drosophila have a preference for sweet taste (Matsuo et al., 2007). However, after the initial attraction that was based on taste, with time, the flies prefer to move towards food that have attractive flavor. Drosophila has a keen ability of differentiating flavor even when paired with sugars. Flavor affect taste preference in flies. There is a genetic regulation on the flies’ odor preference.
In this study, the food preference of the flies was examined in the presence of plain sucrose and to sucrose flavored with banana flavor. Though there was initially an equal distribution to plain sucrose and banana flavored sucrose, with time a majority preferred sucrose flavored with banana Table 1. Though flavor may modulate food preference behavior, the final decision on consuming food is made on the bases of gustatory receptor. Flavor also helps the flies in differentiating palatable food from toxic foods. The observation from this study also suggests how flies use environmental clues to select food. Though insects and mammals are separated by millions years’ evolution, the flavor remains one factor that decides whether the food is appealing.
The flies that preferred the banana flavor within the first 30 minutes, acts as demonstrators and send visual and contact clues to observer flies (Battesti et al., 2012). These flies then eventually follow the crowd. By following what the majority of the flies do, these observatory flies that do not participate in the initial 30 minutes, later follows the clues offered by the demonstrators and this helps them avoid risk associated with trial and error (Battesti et al., 2012). From this study, it is concluded that after 30 minutes of exposure to two food choices, a majority of the flies preferred banana flavored sucrose over plain sucrose.
References:
Battesti, M., Moreno, C., Joly, D. and Mery, F. (2012). Spread of Social Information and Dynamics of Social Transmission within Drosophila Groups. Current Biology, 22(4), pp.309-313.
Jeevan, J. (2012). Study of Food Preferance in Drosophila. M.S. Massachusetts Academy of Math and Science.
Matsuo, T., Sugaya, S., Yasukawa, J., Aigaki, T. and Fuyama, Y. (2007). Odorant-Binding Proteins OBP57d and OBP57e Affect Taste Perception and Host-Plant Preference in Drosophila sechellia. PLoS Biology, 5(5), p.e118.
