Short Communication: Ventilation and Oxygen Consumption During Rest and Locomotion in a Tropical Cockroach, Blaberus Giganteus

The importance of the autoventilation associated with wing movements to gas exchange in the tracheal system of insects is well established (Weis-Fogh, 1967), and data are available on the relative effectiveness of autoventilation and abdominal pumping in ventilatory exchange (Bartholomew & Barnhart, 1984). However, only preliminary information relating ventilatory behaviour and oxygen consumption during terrestrial locomotion have been published (Bartholomew, Lighton & Louw, 1985; Lighton, 1985). Published information on the minimum energy cost of walking and running in insects exists for five species of cockroaches (Herreid, Full & Prawel, 1981; Herreid, Prawel & Full, 1981; Herreid & Full, 1984) and six species of flightless beetles (Bartholomew et al. 1985; Lighton, 1985). Clearly, more data are needed before the relationship between mass and cost of transport in insects can be evaluated. Our studies took place during July and August, 1984 at the Barro Colorado Island station of the Smithsonian Tropical Research Institute in the Republic of Panama. Adult Blaberus giganteus (L.), mean mass 4-33 g, were captured at lights and housed communally in a windowless container measuring 70x50x50 cm. Water and food (rolled oats, cheese and fruit) were available in excess. All measurements were made at night at 25—27 °C. Temperatures were measured with copper-constantan thermocouples connected to Bailey Bat thermometers. Thoracic temperature (Tth) was measured with a 40-gauge thermocouple inserted dorsolaterally into the flight muscles to a depth of about 2 mm and sealed in place with wax. Rates of oxygen consumption (Vo2) were measured with an Applied Electrochemistry S3-A two-channel oxygen analyser using a flow-through system. Airflows were measured with flow meters calibrated against a Brooks mass flow meter. The respirometer was a bottomless box of Lucite (inside dimensions,