CHANGES IN TEMPERATURE, NOT PHOTOPERIOD, CONTROL THE PATTERN OF ADULTECLOSION IN THE TSETSE, GLOSSINA-MORSITANS

The timing of adult eclosion in tsetse, an event that normally occurs in midafternoon, is regulated by the daily cycle of temperature elevat ion. If a temperature cycle is maintained, the rhythm of eclosion pers ists under continuous light or continuous darkness. Artificially shift ing the temperature peak to the scotophase results in a concomitant sh ift in the eclosion pattern. Daily temperature variations as small as 0.4 degrees C are sufficient to establish the rhythm. Eclosion activit y tracks the temperature peak, even if the pulses are of short duratio n (4 h) or with irregular frequencies of 12 or 36 h. The temperature-i nduced rhythm offers a simple mechanism for separating females and mal es. Individuals that pupariate on the same day eclose as adults over a 3-5 day period at 25 degrees C, and in such collections, females are the first to eclose. This distinction makes it possible to collect sam ples of predominately one sex, a feature that may facilitate the colle cting of males for use in the sterile-male technique.