Why Fruit Flies?

Even though fruit flies, classified under the family Drosophilidae, have been used in genetic research on heredity for centuries, people often wonder, why fruit flies? Why do scientists prefer fruit flies to famous lab animals like white mice in the study of genetics? We now provide some answers.


1. Its Size


As everyone knows, fruit flies are small: in fact, they are only 3mm in size, and thus, easy to grow and keep in small containers in laboratories, reducing the hassle of working with big and cumbersome lab animals. Being small and helpless, scientists can manipulate them easily, for example, in anesthetizing and sexing them (refer to bottom post for definition of "sexing").



2. Easy to raise


How difficult can it be? Fruit flies are hardy and resilient to changes in environmental conditions, and only need a miniumum amount of food to survive. And, they feed on almost anything.



3. Short life cycle


Fruit flies only have a full life cycle of about a month. Thus, breeding experiments carried out on flies can garner results in the shortest possible time, since scientists do not like to waste time. The study of various continuous generations of fruit flies can be undertaken in only a matter of a few months. Fruit flies are fertile throughout the year and extremely prolific, producing a new generation every 12 days, or 30 generations in a year! Since they reproduce so rapidly, and in such great amounts, many breeding experiments can be carried out at once, thus there will be greater chances of successful experimens and breakthroughs. Compare all that to breeding chimpanzees. One generation can take decades to develop.






Life cycle of the fruit fly. Taken from http://www.anatomy.unimelb.edu.au/



4. Easily distinguishable


The males can be easily distinguishable from their female counterparts by observing their physical features, making it easy for seperate breeding experiments to be carried out.



5. Embryonic development


The eggs of the fruit flies develop outside the body, thus it is easy to study the effects of mutations on their development.




Can you see the fruit fly eggs? Taken from http://upload.wikimedia.org/wikipedia/en/thumb/c/c4/Drosophila_eggs_Nuuanu.jpg/200px-Drosophila_eggs_Nuuanu.jpg



6. Simple


Fruit flies only have 4 chromosomes, making it easy to study the different effects of different genes on their development. Morever, all the genes, and their functions, had already been identified and stored in databases worldwide, making the information easy to access to be used by scientists.






Fruit fly chromosomes. Taken from http://www.news.bbc.co.uk/



Thomas Hunt Morgan and his beloved flies


Morgan was one of the most famous geneticists who worked extensively with fruit flies. He started working seriously with Drosophila in 1907, with the intention of breeding many generations of flies, and perhaps getting one that is different from the others. He hoped to find one that was mutated. After wasting two years of work, he failed to detect a single mutation. However, he did not give up even after that, and continued with his interest, passion, and devotion to the study of fruit fly genetics.

Most of this information is taken from http://www.columbia.edu/cu/alumni/Magazine/Legacies/Morgan/

Experiment

On Day 1 we conducted hands on experiments to go through the whole process of breeding fruit flies (drosophila). In summary, these are the things that we did:



1. Make fly food
We were told that the ingredients for making the fly food were mainly agar powder, milo powder, mashed bananas, vinegar and yeast. For our very first try, we first poured vinegar into a cup, then added milo powder and agar powder and stirred until the mixture curdled up and was adequately moist for the fruit flies to feed on. The food was also to be the medium in which the flies lay their eggs.



2. Anesthetize the flies
In order to investigate heredity (the passing down of genetic information) in fruit flies, we had to seperate them into males and females. But to do that, we had to anesthetize the flies in order to analyze their physical characteristics. We dipped a cotton bud into a vial of FlyNap, knocked the containers containing the flies on the table to prevent the flies from escaping, and removed the cotton wool enclosing the vials just a fraction in order to insert the cotton bud. All the flies were "knocked out" in just a matter of minutes.





credits of https://www2.carolina.com/webapp/wcs/stores/servlet/CarolinaBio/images/medium/173010_d_gen.jpg



3. Sex the flies
To sex the flies means to seperate them into them males and females. We first tipped the unconscious flies onto a piece of paper,moving them around carefully using a brush to avoid kiling them, and, analyzing them one by one under a microscope, seperated the males from the females. Using our knowledge of the physical features of the males and females, we were able to do so. The males had sex combs on their legs while the females did not. The males had rounder, shorter and darker abdomens than the females. Also, the males were comparatively smaller than the females.



taken from http://www.berkeley.edu/



4. The breeding itself
We put one identified male and female fruit fly into another seperate container containing the previously prepared fly food. We then capped the container with a plastic lid and poked holes in it to enable the fruit flies to breathe. Then all we had to do was to wait for the fruit flies to wake up from the effects of the anesthetic and breed.

Fruit Fly Grow Up Kit

We created a Fruit Fly (Drosophila) Grow-up Kit called WonderGro which comprises of the following items in a package:

l Box (to store everything)
l cup with holes
l packet of agar agar powder
l packet of milo
l vial of vinegar
l packet of mashed banana
Drosophila eggs
(given in small container to prevent squashing)
l stirrer
l instruction manual

vials of fruit flies, taken from http://www.wormman.com/cat_fruit.cfm

prepared fruit fly food, also taken from http://www.wormman.com/cat_fruit.cfm

How does it work???

The food for the fruit flies (drosophila) is made by mixing the agar agar powder, milo, vinegar and mashed bananas in the prepared proportions. The food will only have to be prepared once, as it will contain enough nutrients for newly hatched fruit flies to grow to maturity and complete their life cycle. It will take around 6 days for the drosophila larvae to develop into pupae, and four days for the adult drosophila to emerge from the pupae. The provided cup has a lid which comes with holes for the fruit flies to breathe. After preparing the fly food in the provided cup, which will take less than THREE minutes, the buyers/owners will be able to add in the drosophila eggs (20 per pax) into the cup. The cup is totally transparent and will allow the owners to watch their drosophilas' growth and progress through their entire life cycle! It's that simple!

Commercial Fruit Fly Kit, credits to

https://www2.carolina.com/webapp/wcs/stores/servlet/ProductDisplay?jdeAddressId=&catalogId=10101&storeId=10151&productId=48411&langId=-1&parent_category_rn=&crumbs=n

We even included an instruction manual in the WonderGro package to make everything idiot-proof for everyone. Even 5 year old kids will be able to follow these instructions at ease!!!

1.Add the vinegar from its vial into the provided cup
2.Add in the packet of milo powder and stir
3.Add in the packet of mashed bananas from its packet and spread it out evenly
4.Add in the agar agar powder from its packet. (Note: It will curdle almost immediately after stirring, so try to make the mixture level)
5.Open the small, labeled container containing the drosophila eggs and tip in the eggs carefully onto the fly food
6.Cover the cup with the given lid (with holes)
7.Wait for the drosophila to hatch and go through its life cycle!