Studies On Development And Internal Structure Of The Necrophagous Phorid Fly Immatures

The tiny phorid flies are the most important forensic insects in a relatively sealed space.Their developmental rules play an important role in estimation of the death time of corpse.In this study,at 21?,24?,27?,30?,33?with relative humidity of 75%,the shortest developmental duration of M.scalaris(Loew)and M.spiracularis Schmtiz were observed,the larval body length were measured and the pupal internal structures changes were observed by histological section technique which would complete the developmental data of M.scalaris(Loew)and M.spiracularis Schmtiz and provide a basis for determining the death time of a corpse using necrophagous phorid flies.The main results are as follows:1.At 21?,24?,27?,30?,33?with relative humidity of 75%,the shortest developmental duration of M.scalaris(Loew)feeding larvae are 77.22±1.93h,54.17±2.97h,42.27±2.34h,37.61±1.80h,44.53±1.34h,respectively;The shortest larvae developmental duration of M.scalaris(Loew)are 118.19±0.84h,80.58±3.31h,66.84±2.90h,46.26±1.17h,60.81±2.90h,respectively;The shortest developmental duration ofof M.spiracularis Schmitz feeding larvae are 101.17±1.09h,73.26±1.92h,54.86±1.01h,47.46±1.13h,40.79±4.20h,respectively;Theaverageminimum developmental time ofM.spiracularis Schmitz larvae are 153.83±1.67h,95.57±2.63h,73.25±1.28h,55.76±1.79h,66.32±1.42h,respectively;As the temperature increases,the developmental duration of larvae gradually decrease.2.At 21?,24?,27?,30?,33?with relative humidity of 75%,the fitting equations for the body length and developmental time of M.scalaris(Loew)and M.spiracularis Schmtiz larvae were constructed respectively.The fitting equations of M.scalaris(Loew)larvaeareY=-0.0002X~2+0.0733X+0.4572(R~2=0.9793),Y=-0.0004X~2+0.0951X+0.1356(R~2=0.9595),Y=-0.0005X~2+0.115X+0.4955(R~2=0.9684),Y=-0.0005X~2+0.1232X+0.6901(R~2=0.9853),Y=-0.0009X~2+0.1423X+0.6901(R~2=0.9822);ThefittingequationsofM.spiracularisSchmtizlarvaeareY=-0.0003X~2+0.0940X+0.3813(R~2=0.9763),Y=-0.0005X~2+0.1166X+0.4144(R~2=0.9718),Y=-0.0008X~2+0.1423X+0.5663(R~2=0.9718),Y=-0.0005X~2+0.1375X+0.5881(R~2=0.9644),Y=-0.0013X~2+0.1729X+0.8841(R~2=0.9630).3.The histological section method suitable for the necrophagous phorid fly pupae was established.Samples striped off the puparium were fixed by anhydrous ethanol:chloroform:acetic acid=6:3:1 solution,hyalinized by xylene and ethanol in a ratio of1:2,1:1 and 2:1 ratio.The sections werepatched in the water from 50?to 55?,then stained which could obtain the clean slice.There was no difference in the internal morphological structure of the pupae of M.spiracularis Schmitz and M.scalaris(Loew).4.Under 24?,relative humidity 75%conditions,the pupal internal morphology changes from 48 h to 192 h of M.spiracularis Schmitz and M.scalaris(Loew)were same.The changes of brain,thoracic muscle,gonad and compound eye during the development of pupa have the potential to become the indicator of pupal age,which could be used to estimate the corpse PMI.