Standard metabolic rate of Lepisma saccharina and Thermobia domestica: effects of temperature and mass

Silverfish, Lepisma saccharina L., and firebrats, Thermobia domestica (Packard), are two common Thysanuran pests in the urban environment.  Both species consume starchy materials such as book bindings and paper and are capable of causing extensive damage throughout their lifetime.  In addition, these species can be difficult to control.  Most insecticides, particularly bait formulations, are ineffective, and both species can survive extended periods of starvation.  Their long survivorship time while starving suggests that they have some metabolic modification in comparison to other insects which cannot survive starvation for such an extended period of time.  To investigate this and to compare both species, we measured the standard metabolic rate of both species at 5 temperatures (10-40^oC) across a range of body masses using closed system respirometry.  In addition, both firebrats and silverfish were further grouped into adults (>7mg) and immatures (<7mg).   Combining all species and age groups, temperature had a stronger effect on firebrat V̇_O2 (µl mg^-1 h^-1) than on silverfish V̇_O2 for both adults (firebrat Q₁₀=2.32, silverfish Q₁₀=2.07) and immatures (firebrat Q₁₀=2.86, silverfish Q₁₀=2.57).  In addition, temperature had a stronger effect on V̇_O2 of immature than adults, for firebrats (adult Q₁₀=2.32, immature Q₁₀=2.86) and silverfish (adult Q₁₀=2.07, immature Q₁₀=2.57).  Respiratory quotients were also calculated and had a quadratic relationship with temperature from 10-40^oC.  These results are interpreted with the life histories of both species in an attempt to understand how the metabolic rates of different species and ages show different relationships with temperature.