Entomotoxicology

Over the past 2 decades, drug-related deaths have increased in the United States and other countries. In many instances, these deaths are not immediately reported and the remains may be undiscovered for several days. Because of decomposi-tional processes, estimations of the time of death or postmortem interval are based on analyses of insects and other arthropods infesting the remains. The data most frequently employed are those associated with insect development rates and successional patterns. Recently, the accuracy of these estimations has been questioned in deaths involving narcotic intoxication. Relatively few studies are currently available detailing the effects of drugs, such as cocaine and heroin, in decomposing tissues on the rates and patterns of development of carrion-feeding arthropods. Additionally, there are few data dealing with effects of other tissue contaminants, such as toxins and environmental pollutants, in decomposing tissues on rates and/or developmental patterns of arthropods using such tissues as food. Interest also has focused on the potential use of arthropods as alternate specimens for toxico-logical analyses, in situations in which more normal specimens of blood, tissue, or body fluids are not available. These two areas now comprise entomotoxicology.

Detection of Drugs and Toxins

It is not unusual for remains to be discovered in a highly decomposed or skeletal stage, when there is insufficient tissue for toxicological analyses. There frequently are, however, arthropods or their cast larval or puparial skins still associated with the remains. Various toxic and controlled substances can be detected by analyses of these arthropods and their residues. Generally, arthropod materials have been homogenized and then processed in the same manner as other tissues or fluids of toxicological interest. Analytic procedures include radio-immunoassay, gas chromatography, thin layer chromatography, and high-performance liquid chromatography—mass spectrometry.

Effects of Drugs on Development of Insects

Although many of the studies mentioned documented the potential for use of maggots and puparia as alternate specimens for toxicological analyses, few were concerned with the potential effects of these drugs on the development of the insects ingesting them. In providing an estimate of the postmortem interval, particularly within the first 2 to 4 weeks of decomposition, it has been assumed that the insects will develop at predictable rates for given environmental conditions. That this might not always be true was established by studies on the effects of cocaine on development of the sarcophagid Boettcheriscaperegrina. In this example, maggots were reared on tissues from rabbits that had received known dosages of cocaine, corresponding to 0.5, 1.0, and 2.0 times the median lethal dosage by weight. Two patterns of development were noted. Control and sublethal-dosage colonies developed at approximately the same rate, as indicated by total body length. In contrast, the colonies fed on tissues from the lethal and twice-lethal dosages developed more rapidly. This difference continued until maximum size was attained and the postfeeding portion of the third instar was reached. Due to the increased rate of development during the feeding stages, pupariation occurred first in the lethal and twice-lethal colonies, but the actual duration of the puparial period was the same for all colonies and there were no detectable differences in puparial mortality.

The potential significance of these alterations in the rates of larval and puparial development is illustrated in trying to establish the postmortem interval of a Caucasian woman, approximately 20 years of age, discovered in a pine woods area northeast of Spokane, Washington. The body was in the early bloated stage of decomposition and had extensive populations of maggots on the face and upper torso. Maggots were submitted to the entomologist after being refrigerated for 5 days and reared to the adult stage. Two species were identified from the adults: C. cadaverina and Phaenicia sericata. Typically, P. sericata oviposits within 24 h following death, whereas C. cadaverina oviposits 1 to 2 days following death. Three size classes of maggots were present on the corpse. The first consisted of maggots measuring 6 to 9 mm in length that were consistent of a period of development of approximately 7 days. The second consisted of smaller maggots, consistent with continued oviposition by adult flies. The third consisted of a single maggot measuring 17.7 mm in length and indicative of a developmental period, under prevailing conditions at the scene, of approximately 3 weeks. Given the other data associated with the case, this period did not seem possible. The possibility that this maggot had migrated from another nearby source was eliminated, as no carrion could be located nearby and the probability of only a single maggot migrating was low. The alternate explanation was that the maggot's growth rate had been accelerated in some manner. It was learned that the victim had a history of cocaine abuse and that she had snorted cocaine shortly before her death. This maggot had most probably developed in a particular pocket in the nasal region containing a significant amount of cocaine.

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