SOFT 2004 Meeting Abstracts - Society of Forensic Toxicologists

M44
FORENSIC ENTOMOTOXICOLOGY: A STUDY IN THE DEPOSITION OF BARBITURATES
INTO THE LARVAE OF THE BLACK BLOW FLY, PHORMIA REGINA
Michelle R. Peace, M.F.S.* and Alphonse Poklis, Ph.D., Department of Pathology and the Forensic Science
Program, Virginia Commonwealth University, Richmond VA 23284
Due to events in severe decomposition, either no soft tissue remains on which to perform a toxicological
analysis or putrefactive fluids complicate and interfere with the analysis of the soft tissues. The purpose of
this experiment was to study the trends in the deposition of barbiturates into the larvae of the black blow
fly, Phormia regina, in order to better understand the value of entomological evidence as toxicological
specimens. Drug deposition was analyzed by linear regression to find a correlation between whole larvae
drug concentration and food source drug concentration. P. regina larvae were raised at 21°C on pork
homogenized with three concentrations of barbital (200, 400, 800mglkg), phenobarbital (20, 40, 80mglkg),
pentobarbital (20, 40, 80mglkg), and thiopental (15.5, 31, 62mglkg). The middle dosage of each drug
reflected the LDso of the drug in rabbits. At the end of the feeding stage, the larvae were harvested,
washed, and frozen. Ten larvae were subsequently homogenized, diluted in 2 ml water, and subjected to a
liquid-liquid extraction. The extracted drugs were derivatized with MethElute and analyzed by GCiMS. In
the concentration ranges investigated, the concentrations of barbital, phenobarbital, pentobarbital, and
thiopental found in the larvae strongly correlated with the concentration of the drug in the food source (R 2
= 0.9976, 0.9914, 0.8938, and 0.9095, respectively). Larvae feeding on pork homogenized with 800mglkg
of barbital accumulated 1.8 times more drug than those feeding on 200mgikg. Larvae which fed on the
high concentrations of phenobarbital, pentobarbital, and thiopental accumulated, respectively, 3.1, 5.4, and
68.5 times more drug than those that fed on the low concentrations of drugs. This data indicated that as the
Iipophilicity of the drug increased, the larvae accumulated significantly more drug.
Keywords: Entomology, Toxicology, Barbiturates
Page 327