Respiration of maggots

Introduction

Aerobic respiration is the process in which glucose and oxygen, through the action of enzymes in mitochondria, produce carbon dioxide, water and lots of energy. In this experiment the use of oxygen in the aerobic respiration of maggots can be seen in that, in a sealed container, the level of oxygen reduces with time.

Equipment required

• PC with PicoLog datalogging software installed
• DrDAQ data logger
• Oxygen in air sensor
• Temperature sensor
• 2 litre beaker
• 100 ml beaker
• beehive shelf
• gauze fabric
• rubber bands
• trough - ice-cream container
• water
• live maggots (keep in fridge until ready for use) - available from fishing tackle shops

Experiment set up

1. Connect the DrDAQ datalogger to the parallel port (or USB if you are using a USB to parallel port adaptor).
2. Fix the temperature sensor to the oxygen sensor with a couple of rubber bands and mount them pointing upwards on the beehive shelf. A little Blu Tack is useful for anchoring them in place securely. Run their connecting leads through the central hole of the beehive shelf.
3. Fill the trough with water at room temperature to a depth of about 3cm and place the beehive shelf with the sensors into it. Plug their connecting leads into External sockets 1 and 2 on DrDAQ.
4. Put about thirty maggots into the 100 ml  beaker, place a piece of gauze fabric over its open end and anchor in place with a rubber band. Place this beaker in the water alongside the beehive shelf. You may find it useful to anchor it down with Blu Tack.
5. Now place the 2 litre beaker, upside down, over the beehive shelf and 100 ml  beaker and into the water so that it seals in the air.

Figure 1: the equipment set up

A centrally heated and thermostatically controlled room or laboratory should not change much in temperature, probably only of the order of 2-3 °C, assuming that windows are not suddenly opened or lots of bunsen burners lit.

Carrying out the experiment

1. Load PicoLog and configure it to collect readings of the oxygen and temperature sensors every minute for a whole day (1440 samples).
2. Set it to start recording.
3. When datalogging is complete, display the graphs of % oxygen and temperature against time.

Further study

An extension to the experiment could be to place the trough, beehive shelf, beakers. maggots, etc into a thermostatically controlled heated water-bath, or on a hot-plate, and see if temperature affects the rate of respiration and so the speed of uptake of oxygen. Temperatures up to around 40°C are OK.

A further investigation could be to see if light intensity has any effect, illuminating the maggots with a light bulb and additionally recording the light level. One of the energy-saving fluorescent bulbs should be used so that little direct heating is caused. Readings should then be collected from the oxygen and temperature sensors connected to DrDAQ externally and from DrDAQ’s on-board light level sensor.

Credits, comments and further info

This experiment was written by Chris A Butlin of Sutton upon Derwent, UK.