Parasitic Hymenoptera as Forensic Indicator Species

Abstract

Necrophagous insects are the most important ecological evidence associated with a decomposing corpse. Insects provide insight into estimating the post-mortem interval PMI , assessing whether a corpse has been moved, use in toxicological analyses, and provide utility in surveillance and as sniffer systems. Necrophagous Diptera are regarded as the most important forensic indicator species, largely because they colonize a corpse within minutes of death. Other types of carrion-inhabiting insects also offer value, although more limited than flies, to forensic investigations. Perhaps, the most neglected of these groups is the parasitic Hymenoptera, a group comprising several species that utilize necrophagous flies as natural hosts. Parasitic wasps extend the PMI window to include the period of time after necrophagous flies have emerged to when a corpse is discovered. Wasp host preferences and seasonal occurrences can reveal if a body was moved from another location prior to discovery. Foraging behavior of adults can be used to locate concealed bodies and potentially aid in combating entomological terrorism agents. Presently, the full potential of parasitic Hymenoptera as alternate forensic indicator species has not been explored. This chapter relates the life history characteristics of parasitic wasps to their potential usefulness in forensic applications.

First list of parasitoids in flies of medical, veterinary, and forensic importance in Rio Grande do Sul – Brazil

“…Among the collected parasitoids, only N. vitripennis and T. zealandicus have already been reported in a forensic case study (Turchetto and Vanin, 2004). According to Rivers (2016), the potential use of parasitoids of necrophagous flies as forensics evidence is still not very explored due to the lack of knowledge about the biology, ecology, and behavior of these species. The occurrence of N. vitripennis, S. cameroni, S. chontalensis, and S. endius in just some months can be important from the forensic point of view because seasonality is especially useful to determine if a corpse was removed from the crime scene (Rivers, 2016).…”

“…That can be caused by a toxin injected by the female wasp during oviposition, by poisoning through salivary secretion or by feeding (Quicke, 1997;Asgari and Rivers, 2011). These hymenopterans use larvae, prepupae, or pupae of flies to develop, and because of this; they are found next to the sites that the flies occur (Rivers, 2016).…”

“…Precise information on the species of these families that occur in such different ecosystems is of the utmost importance for both medical and forensic entomology (Voss et al, 2009). According to Rivers (2016), these insects can widen the PMI window to include the time after necrophagous flies cease feeding, reveal if the corpse was moved to another location prior to discovery, indicate the period of the year that death occurred and help to find concealed bodies. The information about the natural occurrence of these hymenopterans is also important to develop control strategies of these dipterans in a given region because parasitoids in high abundance are probably the most promising to rearing and mass release (Geden and Hogsette, 2006).…”

Parasitic and predatory behavior of Alysia manducator (Hymenoptera: Braconidae) on blow fly larvae feeding on an adult pig carcass in the Western Cape Province of South Africa: preliminary observations and forensic implications

“…Among them is a special group known as parasitoids. These parasitic wasps are necrophilous in nature; however, they do not feed on vertebrate carrion [ 6 ]. Instead, they make use of the immature (e.g., eggs, larvae, prepupae, and pupae) stages of blow flies (Diptera: Calliphoridae), flesh flies (Diptera: Sarcophagidae), house flies (Diptera: Muscidae), scuttle flies (Diptera: Phoridae), cheese skippers (Diptera: Piophilidae), and rove beetles (Coleoptera: Staphylinidae) as suitable hosts for the breeding and development of their offspring [ 6 – 11 ].…”

“…This, in turn, may interrupt insect colonization and therefore possibly, the decomposition of the vertebrate carrion. In addition, it can jeopardize the attempt to raise collected immature insect specimens (serving as their hosts) to adults for accurate species identification and/or their application in minimum time since death estimation during forensic investigations [ 6 ]. Equally important, wasps can cause post-mortem lacerations and injuries on vertebrate carrion which can potentially create entry sites for other insects and possibly mislead forensic investigators during cause-of-death investigations [ 21 , 24 ].…”