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Objective: To study the growth and development patterns of the larval weight, the content and composition of hemolymph soluble proteins of Lucilia sericata and Chrysomya megacephala (Diptera: Calliphoridae) under different temperat- ures and accumulate biological data on necrophagous flies in Shijiazhuang area. These data would help to provide a scientific basis for deducing the postmortem interval (PMI) in criminal investigation.Methods: The adults of L. sericata and C. megacephala were collected outdoor and bred in laboratory, provided with a diet of sugar, powdered milk and water. Then they were maintained in an incubator where the temperatures were 24℃, 28℃, 32℃, the humidity was 50~60% and the photoperiod was 12h: 12h.At 24 hours post hatch the larvae were began to collect. From then on, every 24 hours collected once until 50% larvae had pupated.Ten larvae were collected killed immediately in 80℃water, and then preserved in 70% alcohol mixed with solution. The samples were taken out from the preservation solution. The liquid on the surface was blotted up by filter paper then weighting them by electronic balance.Sixty larvae were collected cleaned with 75% alcohol two times and ice distilled water some times. When the larvae dried using the filter paper, they were cut by dissecting needle. Hemolymph was placed at glacial centrifugal tube, centrifuged at 10,000r/min (10min, 4℃). Clear supernatant liquid was conserved at -20℃.Using QHS method to determine the content of larval hemolymph protein.The larval hemolymph proteins were separated by gradient SDS-PAGE and analyzed using FR-980 Biological Electrophoresis Image Analysis System.Data were analyzed using SPSS 11.5 and EXCEL 2003. Pictures were handled with PHOTOSHOP.Results:1 Biochemical character of two species of necrophagous flies during the development of larvaeAt 24℃, 28℃, 32℃, L. sericata arrived at their maximum body weights at 5d, 4d and 4d respectively; C. megacephala arrived at their maximum body weight at 5d, 4d and 3d respectively. After then, the body weights of two species decreased as daily age increased. A trinomial equation was fitted as the form: Y=b0+b1X+b2 X2+b3X3 to estimate the relationship between the body weight and age of larvae. The fitting results were satisfactory. At 24℃, 28℃, 32℃, the protein content of L. sericata reached maximum at 5d, 4d and 4d respectively; C. megacephala reached maximum at 4d, 4d and 3d respectively. After then, the protein content decreased as daily age increased. A trinomial equation was fitted as the form: Y=b0+b1X+b2 X2+b3X3 to estimate the relationship between the protein content and age of larvae. The fitting results were satisfactory. 2 Effect of temperatures on the biochemical characterAt 24℃, 28℃, 32℃, larval body weight increased with increasing age. After they reached maximum, they decreased slightly. But the time shortened as increasing temperature.At 24℃, 28℃, 32℃, larval protein content increased with increasing age. After they reached maximum, they decreased slightly. But the time shortened as increasing temperature. 3 Development profiles of hemolymph soluble proteins during the larval stages in two species of necrophagous fliesAt 24℃, 28℃, 32℃, thirteen distinct component bands were detected. They were A band(230KDa), B band(79KDa), C band(73KDa), D band(46KDa), E band(40KDa), F band (37KDa), G band (31KDa), H band(L. sericata: 28KDa, C. megacephala: 27KDa), I band (L. sericata: 27KDa, C. megacephala: 22KDa), J band (L. sericata: 22KDa, C. megacephala: 18KDa), K band (L. sericata: 18KDa, C. megacephala: 17KDa), L band (13KDa), M band (11KDa). The content of every protein band present various regularities. In all protein bands, the content of band A, (B+C), and G was differentiated during the larval third instar. The content of“A”band increased with increasing age. A single linear equation was fitted as the form: Y=a+bX to estimate the relationship between the protein content of“A”band and larval age. The fitting results were satisfactory.Conclusions:1 Under three constant temperatures, the body weight of L. sericata and C. megacephala increased with increasing age. After they reached maximum, they decreased slightly. The time shortened as the increasing temperature.2 Under three constant temperatures, the protein content of L. sericata and C. megacephala increased with increasing age. After they reached maximum, they decreased slightly. The time shortened as the increasing temperature.3 Under three constant temperatures, thirteen bands were detected in larval hemolymph. In all protein bands, the content of band A, (B+C), and G had significant differences during the larval stage, so they would be applied to deducing the PMI.
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