Alcoholic Fruit Flies


There have been several papers in recent months on alcohol consumption by one of our smaller neighbors – the fruit fly. Before we rush off and criticize their drinking behavior we need to keep in mind that there are medicinal benefits from supping a wee dram.

Fruit flies start their drinking early on in their lives. The larvae eat the yeast on rotting fruit and develop a tolerance to alcohol when very young. A paper in Current Biology last month by Milan et al from Emory U brings out the medical benefits of their self-medication by killing parasites in their blood (1).

Endoparasitoid wasps inject their eggs into fruit fly larvae to provide a live meal for their offspring. Firstly, an alcoholic larva is repellent to the wasps, and secondly, the alcohol in the blood kills off the parasites. If a larva gets infected, it is aware of what happened and goes off to find some alcohol to sort itself out.

Of course, it’s not only parasites that fruit flies have to worry about. Their busy lives can, like ours, be quite stressful. Male fruit flies spend a deal of their time finding mates and if successful, the levels of neuropeptide F are enhanced. If their love life is going badly the levels are reduced.

For the bio-geeks among us, neuropeptide F controls the feeding response in the larvae and when it is reduced in older larvae they get into burrowing mode. It is the analogue of neuropeptide Y that we mammals make use of to regulate our feeding habits. Neuropeptide Y deficient mice overeat and end up with a severe obesity problem.

Now Shohat-Ophir et al from U Cal. SF reported on their experiments with groups of male fruit flies and their drinking habits in the current edition of Science (2). They took some males (fruit flies, that is) and introduced them to a large group of eager females and checked out their alcohol consumption. They then compared that to another group of males after introducing them to a group of pregnant females who had no interest in amorous males.

They noted that the alcohol consumption was markedly higher in the group of males who had been put under stress by universal rejections. Of course, they weren’t just allowed to drown their sorrows in peace, but, like their successful colleagues, were thrown into the blender and the levels of neuropeptide F measured. A successful love life led to high levels and rejection led to low levels and loss of control on the alcohol.

  1. http://www.sciencedirect.com/science/article/pii/S0960982212000759
  2. G.Shohat-Ophir, K.R.Kaun, R.Azanchi and U.Huberlin, Science, 335, 1351, (2012)



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Gases And The Greenhouse


The Danes have a good lifestyle on average and a system that works towards a healthy population. Like most of the developed world, they are concerned about the state of their hearts and have been monitoring their citizens for almost a quarter of a century.

They have seen the average weights go up for everybody whether fat or thin and they have developed a theory for why that should be. It is due to the burning of fossil fuels increasing the carbon dioxide levels in the cities. They explain that the increased levels of carbon dioxide may be stimulating the orexin levels in the brain thus making us all want to eat more (1).

Of course, this is just a theory, but they do have supporting information. The first observation they mention is that in the US, the obesity rates increased fastest on the east coast where the carbon dioxide levels are highest.

Secondly, they have a fascinating snippet in that in a wide range of laboratories where there were animals on normal diets, the animals are now heavier on that diet than they were some years ago. This goes for a survey of 20,000 animals from eight different species, which included mice, cats, dogs and monkeys.

Finally, a paper hit the streets that showed how the acidity of our blood can effect our orexin levels. They have checked this out with six guys in special environmentally controlled rooms and found that an increased carbon dioxide level had them eating 6% more food.

So we’re back to a life in the fresh air away from pollution and preferably wandering around in the mountains. For those of us who are stuck in our suburbs we will have to steer clear of beer and sodas and have lots of pot plants around us hungry for our exhalations on which to grow larger. If we have a greenhouse, the gases inside may help us slim


  1. http://sciencenordic.com/new-theory-co2-makes-you-fat


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Teaching Young bees


Honey bees have a well organized career path with different duties at different ages. When young, they sort out the incoming nectar, feed the larvae, keep the place tidy, and build new comb. Later on, they become foragers and collect water, nectar and pollen.

They can be trained to take home sucrose and recruit others to help and scents can be used to take them to fresh sources. Young, eager foragers are the easiest to train using scents to indicate sources according to a new paper in the Journal of Experimental Biology (1).

When freshly emerged, the young bees have trouble getting their minds on the job and don’t do so well. The same is true of old foraging hands who have got set in their ways. For the old girls there isn’t much hope, but for the young ones science can come to the rescue.

Behrends and Scheiner showed that by spiking the nectar with octopamine, the young foragers got right on top of the task in hand. It wasn’t helpful with teaching an old bee new tricks though.

Octopamine is a neural hormone that plays a major role in learning and memory for bees and fruit flies, but clearly only on the young ones. It has other functions as well, but so far we don’t know how they change with age. For us it has rumored fat control properties, but doesn’t seem to help with our learning as the addition in slimming remedies haven’t been shown to be all that efficacious.

  1. A. Behrends & R. Scheiner, J. Exp. Biol., 215, 1076, (2012)


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Farming Herds Of Aphids


Yesterday’s post mentioned the farming characteristics of ant populations who look after herds of aphids. Now if you’re an ant this is serious husbandry information and continues to be a problem with our (human) interference in the natural scheme of things.

Now what about our interference in ant farming? Johansson and Gibb of Umeå U have had a look at our forestry practices on ant husbandry of aphids (1). They looked at the spruce forests in Sweden and how clear cutting affected the ant honeydew harvest.

They interviewed a large number of ants with a pretty invasive approach. Firstly theyweighed a large number on their way to work as well as a large number returning from herding duties. But that’s not all. They also put the squeeze on and made some worker ants give up their load.

The honeydew was then analyzed. So what is the effect of clear cutting? The sugar content is lower and the amino acid content is higher. That is the honeydew is a good indicator of the sap content being processed by the herds of aphids.

Does this matter, I can hear you asking. It does to the ants. The ants living in the clear-cut areas were physically disadvantaged as they grew smaller heads and could store less honeydew. In summary, clear cutting is bad news for ant populations.

Just as well we don’t allow ants to vote.

  1. http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0032817;jsessionid=D119C2E7A6F74323C0BB82B5A949B8E6


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How We Predators Should Manage Our Prey


As a member of the world’s top predator class I take an interest in keeping my meals coming with special emphasis on farming as we don’t have sufficient of our prey species roaming wild to keep us feeling complacent. This leaves the question open as to what do other species do when it comes to securing their food supply.

The usual answer is to fight for it. Ants, though, are rather more thoughtful and have introduced farming so that they can harvest honeydew. Of course, they will fight to protect their aphid herds in the same way we will defend our cattle to ensure our milk and meat supply.

It turns out that farming, or perhaps managed hunting, is practiced out in the wild world far away from humans and state regulations. The ecologists among us theorize that predators have an effect on the diversity of prey species and will eat their favorite delicacies thus encouraging others to proliferate.

In order to test this, Ishii and Shimada set up a laboratory with two types of bruchid beetles, C chinensis and C macalatus and studied these for a while (1). Bruchid beetles munch away on crops, but they are not particularly good neighbors and C macalatus ousted all C chinensis from the lab-world in just a couple of weeks.

However, there is a wasp, A calandrae, that likes to lay her eggs in these beetles giving her young a nice fresh food source to munch through after hatching. This wasp was introduced into lab-world and she rather favored C maculatus as a host and in 20 weeks these little bruchids no longer had the advantage.

As always, things are not quite as simple as that our wasp friend had a simple preference. When lab-world was observed over time, it was clear that our wasp was having a run on one beetle and then the other causing cyclic beetle population oscillations, while managing the population nicely for her own offspring.

So it seems that even parasitizing wasps know one beetle from another and are sharp enough to manage wild populations of species that they hunt. They are sensible enough not to drive their preferred target to extinction. It is a pity that we still don’t seem to have learned the same wisdom.

Y. Ishii and M. Shimada Proc. Nat. Academy. Sci., (2012).   
doi:10.1073/pnas.1115133109

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The Gambler’s Fallacy and Brain Activity


Betting on the toss is something most of us have done at one time or another, even it is as harmless as deciding who should start first in some game or other. Our logic tells us that heads or tails is a 50:50 chance. Of course, logic sometimes goes out the window.

If we repeatedly toss a coin and we get a run of heads or tails, our logic weakens and we misquote the law of averages and bet against the run, even though in calmer moments we know that the chance of that last coin toss is still 50:50 for heads or tails.

This poor judgment is known as the gambler’s fallacy and is very difficult to resist if the run is a long one. In order to see where in our brains we work so hard to make silly decisions, Xue et al has used fMRI scans with a card choice game and have published their data in the Proceedings of the National Academy of Science (1).

The choice was to guess the color of a black or white card so, like coin tossing, each choice had a 50:50 chance. However, the gambler’s fallacy is alive and well and the subjects made bad decisions when there was a run of one color so over the long run, they did rather worse than the 50% correct that would always be approached with enough turns.

The interesting new bit of information is that there was a rush of oxygenated blood to the heads of the subjects about 10 seconds before letting their instinct over-ride their better judgment. To be precise, the blood oxygen levels in the left lateral prefrontal cortex were elevated.

Now remember that the prefrontal cortex is where our emotional responses are buzzing around and that the dopamine and serotonin receptors are making us feel good so its not surprising that our logic can slip a little. If the region was externally stimulated electrically, the bad decisions on card choice were exacerbated.

Would holding our breath before making decisions help, I wonder or would that be counter productive by subsequently increasing our heart rate? Perhaps it’s better to avoid such excitement altogether.

  1. G. Xue, C-H. Juan, C-F. Chang Z-L. Lu and Q. Dong, Proc. Nat. Academy. Sci., (2012). doi:10.1073/pnas.1111927109


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