An investigation of key blow fly (Diptera:Calliphoridae) species of forensic importance occurring in Brazos and Burleson Counties of Central Texas

Abstract

Forensic entomology makes use of an entomologist's knowledge about biology, insect taxonomy, and carrion ecology. This knowledge can be used as a tool to help investigators solve crimes. In order to use entomological information to help solve crimes committed in Texas, a database of pertinent information must be prepared. The two orders of insects that are most commonly used to help establish such things as time of death (Post Mortem Interval), location, and manner of death are Diptera and Coleoptera. Of these orders, blow flies (Diptera:Calliphoridae) are the insects of most importance because they colonize a corpse or carcass first, often within minutes of exposure. Exposed pig carcasses were used to survey the species of blow flies present in Brazos and Burleson Counties. Cynomyopsis (=Cynomya) cadaverina (Townsend), Calliphora vicina (Robineau-Desvoidy), and Calliphora livida (Hall) have proved to be the three most important species to colonize carcasses during the winter and early spring. These are blue bottle flies, and morphologically very similar. The larvae are so similar that taxonomic keys do not distinguish between C. livida and C. vicina. These species of blow flies were chosen for identification using a method involving analysis of their mitochondrial DNA. The results of this study have shown that the species of blow flies in a given geographical area (Brazos and Burleson Counties) differ between seasons and locations, and that analysis of the mtDNA of these flies can be used as a method of identification when morphological methods are unavailable. In addition, some common methods of preservation were tested in order to provide recommendations about how these methods affect the amplification of the mtDNA of preserved specimens.