New Cultures

We cleaned out our old adult cultures completely today and replaced them with new adults taken from other cultures.

In the crossing tubes, a single fly remained alive in each.

Crosses Update

Two of the genetic crosses, vestigal with white eyed and vestigal with wild type have completely died out. Also, our adult white eyed and vestigal populations are depleted as well. We are now creating new adult populations from the class room cultures, and hopefully these will produce enough virgins needed for successful genetic crosses and use of these crosses to evaluate Medelian principles of genetics in the fruit flies.

Crossing Flies Day One

After collecting a small amount of virgin females, we arranged the following test cultures to cross different phenotypes:

• 2 Vestigal Virgins with two White Eyed Males
• 2 Wild Type Virgins with two White Eyed Males
• 2 Wild Type Virgins with two Vestigal Males

We will watch the reproduction of these cultures, along with other cultures, to see how inheritance patterns change with differences in the parent pairings.
Further research will be added in a later post to describe the expected phenotypes of the new offspring.

We Still Couldn't Cross Them-Here's Why

Genetic crosses of different fruit flies have not started yet, because virgin females of each phenotype had not been isolated. Today, we released all remaining adults, sorted the newly hatched flies, and isolated a small number of white-eyed and wild type females into new cultures. Hopefully there will be new flies present in the vestigal culture tomorrow.

Final Sexing Before Thanksgiving/Genetic Crosses

For the last sexing (Wednesday) before Thanksgiving break and the actual genetic crosses of the project, the cultures containing White eyed flies were focused on. Although the other cultures have seen hatchings, white eyed flies had the largest population growth that needed to be addressed in the shortened period.
37 new females and 21 males were accounted for.

For the vestigal flies, the tube containing the largest amount of slime mold was thrown out, because the contaminated food had begun to kill off the flies within that culture. However, the other vestigal culture is well, containing a healthy mixture of adult flies, larvae, and cacoons.

Hatching Update

This week, the fruit fly cultures were moved from the classroom environmental chamber to an incubator set at ____ degrees. This has resulted in an increase in the number of hatched flies per culture; especially with the white-eyed flies. The adults in separate cultures are still thriving, and laying eggs. Sexing information on the newly hatched flies will come in the next post.
Slime molds are still an issue within the cultures, but changes in the levels of food have not done anything to reduce their presence. More research will be done to evaluate this issue.
Next week, virgin flies will be taken from each culture to be used in the genetic crossings of each phenotype.

Second Generation

The eggs in our cultures have finally starting hatching. At this point, they have not been sexed.

• Wild Type
• Three flies hatched during the day--more had been retrieved earlier.
• Larvae are still crawling in the food and up the sides of the culture.
• White Eyed
• Small number of white-eyed (around 4) had hatched over the weekend; one hatched later today.
• larvae are still crawling in the food and up the sides of the culture.
• Vestigal
• Although food is infected, larvae are moving within it and stabilizing on the sides of the culture.
• 5 hatched during the course of the day, none from the weekend.

November 3 Update

Sexing of remaining vestigial adults:
20 females and 2 males.

Sexing the flies this time was easier, because another distinguishing trait between the two sexes was also used: male fruit flies have dark patches of sex combs on their upper limbs, while female fruit flies only have sparse hairs.

Observations of the other cultures:
Wild type eggs/larva--larvae are still present in the food, and chrysalises on the sides of the culture have still not hatched. Slight discoloration that can be attributed to slime mold growth is also present.
Wild type adults--only one is left alive (a male); more flies may need to be added into this culture.
Vestigial Developing flies--larvae are still digging tunnels in the food, and chrysalises on the sides of the culture have not yet hatched.
Vestigial Adults, previously sexed-- 11 have died, 10 are still alive, and there is no evidence of reproduction within the culture.
White eyed--the culture is still thriving overall, but a large number died in the last 24 hours (no sufficient time to get a count). Larvae are still burrowing in the food source.

**For future reference: When genetic crosses begin, females will have to be counted in the morning. If there are old females mixed in with males, they will need to be killed or released. Newly hatched females will be moved to a separate culture, because they are still virgins for their first 10 hours of life. If they are left to have sex after this time period, they are useless for genetic crosses, as they can store sperm from more than one parent and the specific genes that the offspring will have will not be evident.

Life Cycles: November 1

After a long weekend, many changes were noted in the cultures of fruit flies.

• Vestigal:
• Only two males were left alive in the vestigal culture. Because of this, we had to take flies out of the teacher's culture and add them to ours. Then, they were sexed in two groups. For the first group, there were 6 females and 10 males. For the second group, there were
• In the culture that had been contaminated with slime mold (which the adults had been separated from), metamorphic casings had appeared on the sides of the container and larvae were also visible within the food.
• Wild Type:
• Within the cultures for the wild type flies, the larvae had made metamorphic casings, while others were still scurrying around the food as worms.
• For the adults, only three were still alive, and had not laid any new eggs.
• White Eyed:
• The many adults that had been added to the white-eyed sample were still thriving, but had not laid any new larvae. Some were still visible in the food, but had not progressed to the stage where they made metamorphic casings

For future reference:
--While food should be kept in a one-to-one ratio, there should be less of the food and water added total. Because slime molds accumulate so quickly in the cultures, lessening the amounts of food might be beneficial to the prolonged survival of the flies.

Weekend Update

This week with my flies:
--All but two of the white-eyed flies died; Friday a large group of others from the original teacher culture were moved to mine (stats on sex to come later).
--There was evidence of larvae in all three cultures.
--Slime mold grew on the food supply of the wild-type and vestigal; because there was larvae within that food, the adults were moved to new cultures with clean food supply and the larvae were kept in the old food supply until they crawl up the sides of the culture.

Day (?)-More Deaths and Stock Culture Additions

When I went to check on my cultures this morning, I found that the death toll had exceeded to the following (these are totals, not deaths specific to today):

• Vestigal--2 dead
• Wild Type-- 1 dead
• White Eye-- 3 dead

However, there were some new additions to the cultures as well. Thankfully, the lone female in the vestigal culture had not died, but I added two females from the original stock culture held by Mrs. Morrison to be safe.
Also, worms were visible deep in the food of the Wild type culture, along the sides of the container. While actual worms were not visible in the other two cultures, the holes in the food associated with worms were present in the vestigal culture.

They're Dropping Like Flies!

Sorry, I couldn't resist.


It is with great sorrow that I record the deaths of two male flies, one from the white-eyed group and one from the vestigal. Time of death is estimated to be sometime between class on Wednesday and the time I checked on the flies Friday morning. Luckily, no females died, as we only have small amounts of females in each vial.

Day 2: Stock Cultures & Sexing, Part 2

Today's section of the experiment focused on constructing the vials that our first generations of fruit flies would be living in. Using the standard procedure (see research links for exact steps), my lab partner and I made vials for the white-eyed, vestigial, and wild type fruit flies. Then, these individual groups were put under the microscope and evaluated for sex. Males displayed fewer abdominal sections and black splotches on their anterior ends, and females had a greater amount of abdominal sections and no dark coloring on their anterior ends. In each group, there was a fewer amount of females than males.When we finished sexing the flies under the microscope, they were returned to their respective food vials and put in the environmental chamber.

Research: Life Cycles

The general life cycle for Drosophila melanogaster has four stages: egg, larva, pupil, and adult. If the temperature of the environment is around 21 degrees Celsius, the fruit fly will undergo the egg and larval stages for eight days, and pupa for six; their time as an adult can span up to several weeks.

The eggs hatch around twenty four hours after they are laid. The larva that emerges from the egg will have two molting periods, during which the cuticle, mouth, hooks, and spiracles are shed. The larva is called an instar during the periods of growth before and after molting. Thus, the fruit fly has three instars. The puparium develops from the third instar which becomes hard in texture and dark in color.
The puparium is where metamorphosis takes place. Just before the adult fly emerges from the puparium, the pupa darkens. Approximately 24 hours before the adult fly emerges, one can see the folded wings and the pigment of the eyes if one looks closely through the puparium.
Upon completion of metamorphosis, the adult forces its way through the operculum (anterior end) of the puparium. Initially the fruit fly appears light in color with a long abdomen and unexpanded wings. In just a few hours the fly gets darker in color, rounder in the abdomen and extends its wings.
Approximately 48 hours after emerging from the puparium, it is possible for females to start laying eggs. However, there are only 12 hours that a female can be considered virgin after emerging as an adult. After reaching this maturity, the flies are fertile for life. A female fruit fly can store sperm after a single insemination and use it for many reproductions; therefore it is important to use virgin females for genetic crosses.

Day 2: Stock Cultures & Sexing, Part 1

Stock Culture Sexing (In-Class Notes):
--Anestitizing happens in a separate vial
--flip vial over, flies move up (need to be a top surface)
or bang flies to the bottom of the vial
Uncap vial with food and flies, while still banging, overlap with new vial, bang flies into new vial and reseal

--Flys are anestitzed with "Fly Nap" (too much kills them!)
--anestitize within the vial, use stick with cotton on the end.
--1st flies are white-eyes, 1:1 ratio for food and water
--sexing 1st thing, use microscope, separate females & male
How can you tell the sex?
**black anterior ends are males
only males have a sex comb (fringe of black bristles on the forelegs)
tip of the abdomen is elongated and somewhat pointed in females and more rounded in males
abdomen of a female has several segments, whereas the male has only 5

• 5 males, one female in white-eyes 
• 8 male, one female in wild
•   3 male, 2 female  in vestigal 

     To be researched in correlation: life cycles, morphology, care & keeping

Day 1: Introduction and WAY too much information

If you're here because you're my AP Biology teacher, I hope this meets your standards. If you're here because you read my real blog, you might want to go back there. And if you just loooooove fruit flies? I highly recommend you seek psychiatric help.


Classification: Drosophila melanogaster
In Drosophila melanogaster wing type is controlled by an autosomal or non-sex-linked gene. Flies having the dominant gene for normal wings (V) would have either a VV or a Vv genotype. Flies with normal wings have fully developed wings and are able to fly. Those having no dominant (V) gene would have vestigial wings and would have a vv genotype. Flies with vestigial wings have nothing more than vestiges or degenerated elements of wings and are unable to fly. However, they can still jump and run quite well. The inheritance of these traits follows the simple rules for alleles having a dominant - recessive relationship with the sex of the fly having no influence.

Eye color is controlled by a sex-linked gene. More specifically, this gene is X-linked in Drosophila melanogaster. Male flies with red eyes having the dominant gene for red eyes will have an XWY genotype. Female flies with red eyes having the dominant gene will either have an XWXW or XWXw genotype. Male flies with white eyes (the recessive trait) will have an X wY genotype. Female flies with white eyes will have an XwXw genotype. Remember that in Drosophila melanogaster males are heterogametic and females are homogametic. Eye color in Drosophila melanogaster is actually controlled by multiple alleles, however, we are only examining the most dominant (red) and most recessive (white) alleles in the allele dominance heirarchy. Because the genes for eye color are X - linked, the sex of the fly has a definite bearing on the frequency of the red and white phenotypes in males and females. Remember to use the W (red) and w (white) symbols as superscripts on your X symbols in order to account for this fact.

These flies were used by Thomas Hunt Morgan to study inheritance.
The fruit fly culture is completely self-contained and needs no cleaning or special care.

Larvae will continually pupate from eggs laid by the adults in the culture. It is important to keep at least 25-50 adult flies in the culture. These adult flies will be busy laying more eggs and ensuring that you will have a successful and constant supply of flies. It is best to keep the fruit fly culture at room temperature (around 70° F). The higher the temperature, the higher the bacterial growth. But, you may want to raise or lower the temperature to control the lifespan of your culture. Optimum reproductive rate occurs at temperatures of approximately 80� F. At around 60� F, reproductive rate slows, thus allowing longer feeding time and longer use from a single culture. 

1:1 ratio is necessary for food media.