Low temperature storage and pupal survival in the Simulium damnosum complex

Pupae of the Simulium damnosum complex were exposed for different time periods to temperatures of 0, 4, 8 and 12 degrees C before returning to ambient temperature (24-28 degrees C). As the period of exposure to the low temperatures increased, pupal survival decreased. A one day exposure even to 0 degrees C had little effect on survival, whereas for a 4 day exposure, the optimum survival occurred at 8 degrees C with a total of 46% emergence. Young pupae (pale cuticle) had greatest emergence after exposure to 12 degrees C, the old ones (dark sclerotised cuticle) after exposure to 8 degrees C. Exposure to the different cold temperatures did not significantly affect the longevity of the emerging adults. Low temperature storage of pupae is thus a viable method for long distance transportation of living specimens of blackflies.