Hello, the Internet!
I’ve just started doing Honours in Biology with the Behaviour and Physiology Research Group run by Prof. Steve Simpson here at the University of Sydney. I’ve had a rabid obsession with biology and ecology for quite a long time. I once owned a small colony of guinea pigs (species name) which became so in-bred over time that they rebelled and built a nuclear device out of lucerne pellets and launched a sneak attack on the rabbits next door. I will never know why.
But back to the reason why I’m writing this – HONOURS! What is it all about?
In my opinion, honours is about getting to plan and execute my own independent research project with a level of freedom that you just don’t get in the first years of an undergraduate degree. For example, I really enjoyed second year entomology – especially the assignment where you learn about nutritional ecology using locusts as an example. However, by the time I had to hand in the assignment paper, I still didn’t really know what the hell had been going on during the experiment, so I didn’t really get a chance to learn about insects and their feeding choices as much as I would have liked to. Hence, Honours! Over nine months you get to think up something interesting to do, do it, and then write about it so that everyone else can read about all the things you did. Sure, there are bound to be quite a few moments of ‘OMFG WTFBBQ ROFLCOPTERS I HATE SCIENCE!’ along the way, but I’m sure that it will all be fairly awesome in the end! (That’s what she said...)
So finally a chance to obsess a little more about insects and things that insects like to eat!
My project will be looking at temperature selection by insect herbivores (plant- eaters) when they’ve either had different things to eat (nutrient availability) or nothing to eat at all (food supply). Insects are ectotherms (like lizards and fish...only not), so they can’t heat themselves from the inside like humans and other endothermic (warm-blooded) animals do. Instead, insects have to use the heat from their environment to control their body temperature so that they can maintain functions as simple as walking around and looking for food.
Many ectothermic animals seem to prefer temperatures that allow them to grow faster and reach maturity first. In the migratory locust (a fifth instar nymph, shown below), this temperature is around 38 degrees.
Sadly for the locust, sitting at high temperatures so that they can grow up faster means that they must eat a *bleep*-load of food in order to stay alive. Therefore, it is likely that access to a very large food supply will be the determining factor in growth prioritisation. My question then, is whether or not locusts will choose lower body temperatures as food supplies dwindle in order to avoid starvation and to conserve their energy?
At the university we have a large room full of locusts, which is handy. This is because I’ll be using the locusts to conduct temperature-selection trials to find out which body temperatures are preferred by the locusts when they haven’t had enough to eat. The locusts will be fed different artificial diets, in which the amount of nutrients can be controlled. Then, the locusts will be put onto a long steel plank that has been heated so that it offers the locusts a range of different temperatures that they can select. I’ll let the locusts settle down on the plank for a while (60 minutes) and then I’ll take their picture with an infra-red thermal imaging camera, which takes rainbow-tastic pictures that look like this:
This way I can find out if and how the body temperature preferences of insects change when they are running out of food. In all, I will do six or seven experiments to look at the effects of amount and timing of deprivation in the locust’s food supply, as well as the importance of nutrient dilution and nutrient ratios available in the food itself, to see if the actual quality of the food available is as important as the amount of food there is to eat.
The anticipated outcome of my research is for a refined understanding of the interactions between temperature selection and the nutritional status of insect herbivores. It will also be relevant to interpreting the plasticity of thermal responses to changes in the food supply. We can also use the results to predict the feeding behaviour and distribution of various insect feeding guilds (like caterpillars and beetles that chew leaves, or sap-sucking aphids, for example) within different thermal environments. This can then be applied to conservation, forestry and agriculture.