DEVELOPMENT AND SURVIVAL OF CHIRONOMUS-TEPPERI SKUSE (DIPTERA, CHIRONOMIDAE) AT A RANGE OF CONSTANT TEMPERATURES

Chironomus tepperi Skuse were reared individually at a range of consta nt temperatures from 12.5 to 37.5 degrees C (2.5 degrees C intervals), with development and survival monitored at regular intervals. C. tepp eri is protandrous, with males developing significantly faster than fe males at the majority of temperatures examined, due primarily to a sho rter final instar. Some individuals completed development at all tempe ratures, however emergent adults failed to successfully inflate their appendages at 37.5 degrees C. Developmental rate increased with increa sing temperature up to 32.5 degrees C, but fell at 35 degrees C. Low a dult emergence at 37.5 degrees C precluded a reliable estimate of tota l development time at that temperature. Survival to adult emergence va ried from 10 to 60%, with highest mortality in the pupal stage at all temperatures. Degree-days (DD) and developmental zero (DZ) estimates f or egg to adult development are 150.5 DD and 10.5 degrees C for males and 167.1 DD and 10.3 degrees C for females. DD and DZ estimates are p resented for each developmental stage. The significance of wide therma l tolerances in a colonist midge species is discussed.