Standard metabolic rates 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 can survive for extended periods without feeding, suggesting that they have some metabolic modifications compared with other insects which cannot tolerate extended starvation. To investigate potential metabolic modifications and to compare silverfish and firebrats, we measured the standard metabolic rate of both species at five temperatures (10, 20, 25, 30, 40°C) across a range of body masses using closed system respirometry. Temperature had a stronger effect on firebrat mass specific VO2 (mlg^-1h^-1) than on silverfish mass specific VO2 for adults (>0.00700g: firebrat Q₁₀=2.32, silverfish Q₁₀=2.07) and immatures (<0.00700g: firebrat Q₁₀=2.86, silverfish Q₁₀=2.57). In addition, temperature had a stronger effect on the mass specific VO2 of immatures than adults for both firebrats and silverfish. Respiratory quotients showed complex relationships with temperature from 10 to 40°C, indicating a change in metabolic substrate with temperature. These results are interpreted with respect to the life histories and environment of both species. Finally, metabolic rates are compared with those of ticks and other arthropods.