Biological and ecological studies on the myiasis producing larvae of Megaselia scalaris with special morphology by scanning electron microscopy.

Laboratory study was conducted on the biology of the phorid fly Megaselia sacalaris. The influence of 3 constant temperatures and various larval densities was researched in the laboratory as these relate to mean life stage rate of development and survival. Flay development on a synthetic diet at 25 degrees C. 75=2% RH and 18 hr photophase was used as the standard. Mean times for development and survival were egg incubation 16.3 h (97.6%); larval period 7.3 days (97.6%); pupal period 9.8 days (95.8%, 91.6%); adult longevity 29.9 days, 24.8 days. Fecundity was 664.8 eggs. One generation required 19.7 days. Data are presented on the influence of 20 degrees C and 15 degrees C on the duration of survival and fecundity life-stages. Theoretical lower thresholds of development for life stages are reported. The adverse effect of larval crowding was reflected at the 100 larvae/10 g diet medium as larval and pupal periods increased. At the 200 larvae/10 g diet medium larval survival declined pupal survival decline began at 100/10 g level. Fecundity was not significant altered. The ultrastructure of the larval stages of M. scalaris was studied by scanning electron microscopy (SEM). Significant changes in morphological features were observed in the anterior and posterior spiracles, but only minimal changes in the labium and mouth-hooks were seen. The ultrastructure of M. scalaris larvae not only provided the chronological transformation of the larval instars, but also can be used to explain their feeding behavior and mode of respiration. Besides, morphological structures useful for specific identification of first and second-instar larvae collected from human corpses may be used in forensic practice.