Cockroaches on a Treadmill: Aerobic Running

Abatraet-Five species of cockroach were tested on a miniature tr~dmill at three velocities as Or consumption (PO>) was measured: Gromphadorhina ~hop~rd~, Blaberus d~cojd~~is, ~ubluber~ posricus, Byrsotria fimugata and Peripluneta americana. All cockroaches showed a classical aerobic response to running: ljol increased rapidly from a resting rate to a steady-state (PO;,,): lliZ on-response varied from under 30 s to 3 min. Recovery after exercise was rapid as well; z,,r, off-response varied from under 30 s to 6 min. These times are faster or similar to mammalian values. VoZ varied directly with velocity as in running mammals, birds and reptiles. ci,, during steady-state running was only 412 times higher than at rest. Running is energetically much less costly per unit time than flying, but the cost of transport per unit distance is much more expensive for pedestrians. The minimal cost of transport (M,,), the lowest po, necessary to transport a given mass a specific distance, is high in cockroaches due to their small size. The new data suggest that insects may be less economical than comparable sized vertebrates.