The joy of going through research with flies ~ Katie Millar

I first got into flies in 2022, after a lecture in the second year of my genetics module, which was solely based on Drosophila melanogaster. I was smitten with these tiny, beautiful things, with their beautiful, bright red eyes, and the gorgeous thoraxes separating them as males and females. I became fixated on the Drosophila melanogaster fruit fly. This obsession started with an Instagram account, @drosothephila.

I was determined to immerse myself in fly research, and following an advertisement for studentship grants to do 8 weeks of research from The Genetics Society, I contacted a fly professor at my university to apply and was luckily successful. My journey in fruit fly research, or research with fruit flies, began with a project based on dietary choice. Using something called a “dietary choice assay” (Churchill et al, 2020), (see Figure 1),

Figure 1

I allowed flies to go into a petri dish, with diets containing different Protein: Carbohydrate ratios. Mated females were the only flies, really, who showed a choice preference, showing a clear preference for feeding on diets high in protein and laying their eggs on diets high in carbohydrates.

I had a lot more questions to ask about dietary choice following my 8-week summer project in my second year, so I asked to stay on in the lab for my third year undergraduate project, doing more work on dietary choice, this time looking at if the texture (hardness and softness) of food overrides usual nutrient preferences, I found that for egg laying, they will prefer a soft diet, and this preference will override their usual nutrient preference, which was surprising as their preference for a high carbohydrate diet in my previous project was very strong!

Having enjoyed these projects in Drosophila melanogaster so much, I decided to pursue a Master of Science by Research, a whole year dedicated to research with no taught content, and finalising with writing it all up in a thesis. This project focused onhow the previous presence of other flies (males, virgin females, and OvoD1 (eggless) females) on a diet patch can affect the dietary choice of other flies. Flies, in fact, preferred these “conditioned diets” and through this, I proposed these were conditioned through: microbe deposition, pheromone deposition and social digestion!

Following these amazing research projects, I knew for sure I wanted to apply for a PhD, and when I saw a PhD advertised involving both FRUIT FLIES and MICROBES, I felt like the fruit fly gods had truly mapped out my brain and blessed me. I was incredibly lucky to get selected for the PhD. I have changed fruit fly families, and I now work on Ceratitis capitata (Medfly), a GORGEOUS fruit fly, although it is unfortunately a pest insect and a very big issue! My PhD project aims to understand its microbiome, where I have a special interest in a microbe, Klebsiella, with hopes we can understand it better as a pest insect.

Figure 2 – A Medfly - Scott Bauer, USDA. Agricultural Research Service

I am very grateful for that Drosophila melanogaster lecture in my second year that started this whole journey off, and I am very grateful to all the fruit fly mums and dads for creating such beautiful creatures. Fruit flies changed my life for the better, and I didn’t know what true love was until I found them. Thank you for all that you have done for me, fruit flies.

I end this post with a beautiful poem that I wrote:

If all things in life are green,

And we are all dressed in our suits,

Then the fruit flies, oh yes the fruit flies,

They do shine, indeed they do.