A THREE-COMPARTMENT MODEL DESCRIBING TEMPERATURE CHANGES IN TETHERED FLYING BLOWFLIES

A three-compartment model is presented that describes temperature measurements of tethered flying blowflies, obtained by thermal imaging. During rest, the body temperature is approximately equal to the ambient temperature. At the start of flight, the thorax temperature increases exponentially with a time constant of 30 s; in steady flight, a temperature of approximately 30°C is reached (ambient temperature approximately 25°C). After flight, the temperature of the thorax decreases exponentially with a time constant of 50 s. Fitting the time courses of the three body compartments, i.e. head, thorax and abdomen, with the model allows the thermal parameters to be calculated. The metabolic heat produced by a blowfly during tethered flight is estimated to be approximately 23 mW.

Warm-Up and Stridulation in the Buschcricket, Hexacentrus Unicolor Serville (Orthoptera, Conocephalidae, Listroscelidinae)

The morphology of the stridulatory organ of the tropical bushcricket Hexacentrus unicolor is described and an investigation is made of stridulatory movements and muscle activities. 1. The song is produced by extremely fast stridulatory movements (320–415 Hz), during which, while closing the wings, a highly specialized file is brought into contact with the plectrum to produce sound. The muscles are activated with the same frequency, i.e. they work synchronously (neurogenic). 2. A few minutes before the stridulation starts, the muscles are activated in a similar rhythm to that pertaining during singing (pattern of spike trains and pauses). As a result, the thorax temperature increases considerably (up to approximately 37°C, 13–15°C higher than the ambient temperature). The frequency of the muscle potentials within the spike trains rises during warm-up. There are, however, indications that no phase displacement of antagonistically working muscles takes place.