Comparing Respiration Rates of Adult Darkling Beetles and their Larvae

Steven Magelowitz, Erik Hauswald


In this experiment we sought to find a correlation between respiration rate and maturity level of darkling beetles. One can infer that an increase in respiration often results in an increase in energy production. Aerobic respiration follows the overall equation C6H12O6  +  6O2    6CO2  +  6 H2O  +  36 ATP. We predict that in conditions of excess glucose, increasing the rate of respiration in the body will increase the ATP energy available for growth. We used the philosophy that organisms that are undergoing development need more energy on average than their full grown counterpart. This led us to the hypothesis that respiration rate will be lower in mature darkling beetles compared to growing larvae.


To test this hypothesis we prepared four different trials: two mealworms, two darkling beetles, three mealworms, and three darkling beetles. The experiment consisted of a gas chamber attached to a respirometer. We ran each trial for a period of ten minutes and monitored the increase of CO2 production. Our controlled variables were temperature and amount of beetles and larvae. Since organisms in development need more energy, we predicted that the mealworms would respire more and produce more CO2 than the adult darkling beetles.


Our results indicated that the rate of respiration was greater for beetle larvae (mean=10.1 ppm CO2/min/unit) than for darkling beetles (mean=7.75 ppm CO2/min/unit P>0.05).


Our results are consistent with out hypothesis. However our t-test does not show that the results are statistically significant. One potential problem with our experimental design was an inaccurate measurement of size. We did not accurately weigh out all of our samples to keep them consistent. We needed to do this as well as run many more trials. Results of Edwards et al. 2005 and Ratliff et al. 2001 on the CABLE web site demonstrated that adult insects actually had higher respiration rates than the larvae. Their methods were similar to ours so we are unsure of a reason for the different results. These studies should be considered another reason to refine our experiment. Based on our own results we should tentatively keep our hypothesis but refine the methods to run more trials and account more accurately for size of the experimental insects.