gustatory input substantially contributes to the preferential ingestion of beer

Bugs and Bass Ale

One year ago, I visited the NSF website on a very regular basis. I was in the midst of a glorious sabbatical (probably a redundancy) during which time I submitted two research proposals. Today I was on that site to update a budget for somebody's project they are resubmitting and for which I would be the evaluator if things work as planned. One interesting thing was that I had forgotten my password but could recall my NSF ID number – a nine digit sequence that my fingers remembered even though I could not have listed those numbers out loud. While navigating the NSF site, my eyes were drawn to a press release that included the word "beer." Neuroscientists at University of California-Riverside have been hard at work.

Apparently fruit flies are attracted to beer and the researchers wanted to know more. More than describing that Drosophila like beer, the scientists wanted to uncover a causal model that explained how the bugs were drawn to the beer. The flies were hungry and thirsty so they had been primed to go after something. Using Bass Ale as one temptation and yeast solution, rotting grapes, or smashed bananas as alternate choices, various strains of fruit flies were allowed to choose between the drinking options and regular sugar water. Some fruit flies had a certain gene removed from their DNA, a gene that would otherwise allow them to detect glycerol. In this diagram, the white boxes represent the strain of files with the Gr64e sequence missing from their bodies. Because they lacked that gene, their attraction to beer was much reduced compared to "normal" wild fruit flies. The quoted line that forms the title of this entry translates to: "flies with taste will drink beer." Not only is this an important discovery, it was sufficiently noteworthy to appear in Nature.

What'll you have, Bugsy?

I, for one, have no problems with paying a research team to do this work. Their article provided answers to some of my question such as "how did they know which liquid the flies ingested?" Turns out the flies were presented with beer dyed one color and another liquid containing another color. That sounds smart and resourceful to me. But I felt bad for the treatment of the satiated flies: "Starved flies were placed in the Petri dishes in a humidified box at 25°C for 2 h, after which they were frozen and scored for abdomen coloration." That's right: starved, allowed to feed, then captured, frozen and torn open to see what was in their guts! Gratefully, no images of this procedure were included in the report. What was also fascinating to me was that the researchers provided the DNA sequence for flies that could taste beer* as well as those variants who could not. All in all, a pretty nice linkage between DNA and behaviors. I wonder what sorts of petty machinations the researchers had to go through to buy beer. Why an Irish important rather than something more local -- even though Sierra Nevada brewing is a nine hour roadtrip away? Especially since NSF funded projects are required to use domestic air carriers for international trips (say, a conference trip to Belgium in 2013), it seems logical that domestic beers would be preferred instead of imports. Apparently the logic fails in this situation.

All of this got me thinking. What other research has been done with insects and beers? The tragic news is that drinking beer can make one more susceptible to mosquito bites. In the geography, that could result in malaria:

Body odours of volunteers who consumed beer increased mosquito activation (proportion of mosquitoes engaging in take-off and up-wind flight) and orientation (proportion of mosquitoes flying towards volunteers' odours). The level of exhaled carbon dioxide and body temperature had no effect on human attractiveness to mosquitoes. Despite individual volunteer variation, beer consumption consistently increased attractiveness to mosquitoes. These results suggest that beer consumption is a risk factor for malaria and needs to be integrated into public health policies for the design of control measures

The moral:

1. It is NOT impossible to receive federal funds to do beer research.
2. Beings who drink beer prefer its taste over other spoiled liquids.
3. If you are going to drink beer in malaria country, be sure to get your shots. Or maybe do shots instead of drinking beer.

* In case you are curious, Gr64a (5’-GGCGTTAAGCAGGTGGAGAG and 5’-CCAGATTCGAACAACTGCTGG),