Re: What is the effect of light on ants?

Hi!

You have very interesting ideas about ant behavior. In trying to find an answer to your question, it may be necessary to reconstruct your hypothesis.

Scientists often need to re-work their questions and hypotheses. This is done to isolate single variables to be analyzed one at a time. Your hypothesis that ants "dig better in the dark because it is cooler" is difficult to test directly because it deals with two variables: light and heat. A good test of these variables will treat them individually first. Therefore, let's look at them separately now. (You appear to be interested in daily changes in these variables, instead of season changes, so I will only address daily changes here.)

Your first variable, solar light, probably has minimal influence on digging by worker ants inside the colony. The reason for this is that the tunnels and chambers of the ants are underground. Light artificially introduced into the colony (such as in an ant farm) may have an affect on the worker ants' digging patterns. Under normal conditions, however, solar light probably does not exist deep inside most colonies where new tunnels are being built.

Your main hypothesis seems to be that heat (derived from solar light) affects ant behavior. Worker ant behavior can be divided into two categories based upon their contact with solar heat. Worker ant behavior can be divided into work done outside the colony (searching for and bringing back food, etc.) and work done within the colony (digging tunnels, etc.). Your hypothesis deals with worker ant behavior inside the colony. Unfortunately, I couldn't find much information on the effects of heat (or light) on the daily inside life of ants. We can make some guesses though.

You suggested that ants might prefer to dig tunnels when it is not too hot. You probably derived your hypothesis from the observation that when people become over- heated their ability to work is impaired. As ectothermic (cold blooded) animals, ants can do little to regulate their body temperatures. Ants not only have to worry about having too much heat during their work, they also have to worry about having too little heat. It has been shown that different ant species prefer foraging outside during different times of day, although I haven't found any research that picks apart the different effects of light and heat to see which of these two variables might be the one responsible for this behavior pattern.

But temperatures inside the soil fluctuate very little on a day-by-day basis. While air is heated and cooled very quickly, soil changes temperature over the course of seasons, not days. I doubt there is much change in the temperature inside the colony from day to day. Therefore, I'd guess that it's unlikely that daily fluctuations in temperature affect the tunnel building activities of the worker ants.

Our re-worked hypotheses would be that daily changes in neither solar light nor heat derived from solar light have an affect on worker ant behavior inside the colony. However, these are untested hypotheses. The process of good science has been described as rational empiricism. Rational means that a hypothesis has been created based on sound logic and previous research. Empiricism means that a rational hypothesis has been tested to show that real, repeatable data exists to support the hypothesis. We've now done the rational part; the next step is to test it!

If you'd like some help designing an experiment to test these hypotheses, please see my previous letter on this subject, or write MadSci Network again!

Thank you for your question,

John