I am trying to find which are the best LEDs and voltages to do the phototaxis experiments.

For that, I was doing experiments with big and small white LEDs (the big ones are much more brighter than the other ones), and with two different voltages: 2,6V and 3V.

This are the results that I have obtained:

As we can see in the pictures, the best results are obtained when we use a voltage of 2,6, and for now big LEDs seem to be better than the smaller ones (we find more differences between flies with clipped wings and flies with intact wings).

But the number of experiments I have done are still not enough to make a good comparison between LEDs size and voltage.

The first picture shows the experimental results obtained with the first white LEDs I have used (using a voltage of 3.0V).

The second one shows the experimental results obtained with the new white LEDs I am using this week (2.6 V).

The first ones are bigger than the second ones, and they are also much more brighter.

We can see in both graphs that there are some differences between flies with intact and clipped wings, being the ones with clipped wings less phototrophic than the others.

For now, graphics do not tell us almost anything about differences between both LEDs.

Yesterday, we cut the wings of half of the experimental flies.

We let them get over for 2 hours, and after that I repeated the same experiment we did last day, letting them choose between darkness and light.

There wasn’t a big difference between flies with wings and flies without wings, but the experiment shows flies without wings have less light preference than the other ones.

Today, I started the experiment with 3 day-old flies.

We found out that they are responding as we thought they were going to do.

There was a white LED in one side of the T-maze, and darkness on the other side.

I run the experiment for 20 seconds, letting them choose between these two conditions. After counting them, I had these results:

82 flies were in the bright side, and 20 were in the dark side.

Tomorrow we will do the same experiment after cutting flies wings, and also we are going to try different LEDs.

I checked the putative non-flying flies we ordered. All are normal when grown at 18°. While developing at 25°, different phenotypes can be seen:
CyK: those flies have curled wings, but can fly.
U2: those flies have curled wings, cannot fly, but still beat their wings while walking (like if they could not figure out that they cannot fly ?).

other flies show no phenotype at all.