PMI Inferring Software Development And Application Of Forensic Entomology

The growth and development of necrophilic insects can provide a unique perspective for Postmortem interval(PMI),but the growth and development rates of different insects are different.Therefore,insect species identification is the premise of inferring PMI.Traditional insect species identification mainly relies on morphological methods,and manual analysis and comparison of insect specific structures.This method is subjective.In addition,the estimation of the growth and development time of necrophilic insects requires the combination of insect morphological characteristics,developmental accumulated temperature,differential genes and hydrocarbons,which is cumbersome.With the development of a new generation of information technology,intelligence gradually replaces labor,and the innovation and application of corresponding software technology emerge.By comparing the phylogenetic analysis methods,collecting the morphological characteristics of wing veins,combining a variety of development age inference methods,the species identification and development time inference are made into software,and the complex professional problems are simplified and practical.It provides a new idea for the combination of forensic entomology and modern information technology.Objective:(1)Collect and sequence necrophilic flies samples from multiple regions nationwide,screen and download relevant data in genebank,research common phylogenetic analysis methods of cadaveric flies,understand the application scope of each method,and provide new ideas for molecular identification in forensic entomology.(2)Combining the morphological identification of flies with modern information technology,explore the software development of wing identification of flies by using image recognition technology,and enrich the methods of species identification of flies.(3)The current methods of estimating the development time of flies are compared and analyzed,and the relevant data system software is developed,which lays a foundation for the popularization and application of the method of inferring PMI by using cadaveric flies.Methods :(1)the study of common phylogenetic analysis methods:samples of collecting flies across the country,sequencing,and download the data in the Gene Bank,it can be divided into a number of different data sets,with ML,BI,NJ method respectively for each data set,phylogenetic analysis using morphological identification and molecular identification verification were analyzed.(2)Development of fly wings identification software: a scanner was used to collect and preprocess the fly wings image,and then the characteristic points of the image were automatically obtained and analyzed.Finally,support vector machine classifier was used for automatic recognition.(3)Development of fly development time data system software: Summarize the general formula of common fly development time estimation methods,use SQLite database to store,delete,modify the data and realize automatic calculation.Results :(1)Research on common phylogenetic analysis methods:Sixteen species of seven genera of necrophilic flies were collected and sequenced.In comparison with nine tree maps of phylogenetic analysis methods of three different data groups,it was found that in necrophilic flies population,BI method was suitable for the data set with large number of samples,ML method was suitable for the remote sequence,and NJ method was suitable for preliminary judgment in the early stage of research.(2)Development of fly vein identification software: use the scanner to collect the fly vein image and preprocess it,then automatically obtain the image vein feature points and analyze them,and finally use the support vector machine classifier for automatic recognition.Seven necrophilic flies could be identified by using fly vein identification software.The success rate of 40 images for each species in the training set was above 85%,and the success rate of 20 images for each species in the external data was above 65%.(3)Software development of fly development time data system: summarize the general formulas of common fly development time estimation methods,and use SQLite database to store,delete,modify and realize automatic calculation.Conclusion:(1)The differences e of common phylogenetic analysis methods of necrophilic flies are compared and analyzed,which provides a relevant basis for the selection of phylogenetic analysis methods in molecular experiments.(2)The software of flies’ wing vein identification is developed,which expands the method of species identification,and provides a new idea for grass-roots public security to identify flies’ species;(3)The development time data system software of flies is developed.In practice,the time prediction process is simplified and the information exploration is carried out.