Abstract

Although well documented in vertebrates, correlated changes between metabolic rate and cardiovascular function of insects have rarely been described. Using the very large cockroach species Gromphadorhina portentosa, we examined oxygen consumption and heart rate across a range of body sizes and temperatures. Metabolic rate scaled positively and heart rate negatively with body size, but neither scaled linearly. The response of these two variables to temperature was similar. This correlated response to endogenous (body mass) and exogenous (temperature) variables is likely explained by a mutual dependence on similar metabolic substrate use and/or coupled regulatory pathways. The intraspecific scaling for oxygen consumption rate showed an apparent plateauing at body masses greater than about 3 g. An examination of cuticle mass across all instars revealed isometric scaling with no evidence of an ontogenetic shift towards proportionally larger cuticles. Published oxygen consumption rates of other Blattodea species were also examined and, as in our intraspecific examination of G. portentosa, the scaling relationship was found to be non-linear with a decreasing slope at larger body masses. The decreasing slope at very large body masses in both intraspecific and interspecific comparisons may have important implications for future investigations of the relationship between oxygen transport and maximum body size in insects.

Links

Publisher Full Text

Authors

Streicher JW, Cox CL, Birchard GF

Institution

Department of Molecular and Microbiology, George Mason University, Fairfax, VA 22030, USA. streicher@uta.edu

Source

The Journal of experimental biology 215:Pt 7 2012 Apr 1 pg 1137-43

MeSH

Animals
Basal Metabolism
Body Size
Body Temperature
Body Weight
Cockroaches
Female
Heart Rate
Male
Nonlinear Dynamics
Organ Size
Oxygen Consumption
Species Specificity

Pub Type(s)

Journal Article

Language

eng

PubMed ID

22399658