Changes in temperature, not photoperiod, control the pattern of adult eclosion in the tsetse, Glossina morsitans

Abstract. The timing of adult eclosion in tsetse, an event that normally occurs in mid‐afternoon, is regulated by the daily cycle of temperature elevation. If a temperature cycle is maintained, the rhythm of eclosion persists under continuous light or continuous darkness. Artificially shifting the temperature peak to the scotophase results in a concomitant shift in the eclosion pattern. Daily temperature variations as small as 0.4°C are sufficient to establish the rhythm. Eclosion activity tracks the temperature peak, even if the pulses are of short duration (4 h) or with irregular frequencies of 12 or 36 h. The temperature‐induced rhythm offers a simple mechanism for separating females and males. Individuals that pupariate on the same day eclose as adults over a 4–5 day period at 25°C, and in such collections, females are the first to eclose. This distinction makes it possible to collect samples of predominately one sex, a feature that may facilitate the collecting of males for use in the sterile‐male technique.