Age-determination in the old-world screw-worm fly Chrysomya bezziana by pteridine fluorescence

Highly significant positive relationships were observed between pteridine fluorescence in the head and chronological age for both sexes of the old-world screw-worm fly Chrysomya bezziana Villeneuve in the laboratory and in field mark-release-recapture trials in Papua New Guinea. The relationships were multiplicative in form and, in most cases, age accounted for in excess of 80–90% of the variance in fluorescence. The rate of accumulation of pteridines with age was greater for males than females, was not affected by the absence or presence of protein in the diet, but was highly dependent on temperature. Pteridine levels appear to be a good indicator of age in this species and will enable the chronological age of wild flies to be determined with a relatively high degree of accuracy.