Effectiveness of wound cleansing treatments on maggot (Diptera, Calliphoridae) mortality

Myiasis is defined as an infestation of the organs and/or tissues of human and other animals by fly maggots. Fly species that normally breed in meat or carrion (Diptera: Calliphoridae, Sarcophagidae) may become involved in cutaneous myiasis by colonizing preexisting wounds. Reports of human wound myiasis contracted in hospitals and nursing homes, especially when patients are chronically ill or bed-ridden, are not uncommon across North America and often result in cases of neglect and civil litigation. Based on a case history dealing with this latter situation and circumstances surrounding the treatment of maggot infestation, we designed an experiment to assess the effectiveness of wound cleansing solutions on maggot mortality. Treatments, consisting of four commonly used cleaning solutions (isopropyl alcohol, Dakin's solution, iodine, and hydrogen peroxide) and a control (deionized water), were applied to experimental units (n=5), with each unit consisting of groups of actively feeding Lucilia sericata maggots (Diptera: Calliphoridae). Every 24h, treatments were applied and mortality was assessed for the duration of the study (14 days). Total mean mortality increased over the duration of the experiment, with an initial large increase (10-25%) after the first treatment application, followed by a gradual increase over the remainder of the study. General differences among treatments indicated greatest mean total mortality for Dakin's solution (sodium hypochlorite) (46%), followed by isopropyl alcohol (42%), Betadine (37%), hydrogen peroxide (33%) and lowest mortality for the control (25%); however, no statistically significant differences were observed among treatments and no treatment resulted in 100% maggot mortality. Traditional wound cleansing solutions may not be sufficient for maggot infestations of pre-existing wounds and supplemental treatments may be necessary to effectively treat cases of wound myiasis.     

Caddisflies assist with homicide case: determining a postmortem submersion interval using aquatic insects

Although few indicators of time since death for corpses found in aquatic ecosystems are comparable in precision to the insect indicators used in terrestrial cases, there are observations that can be useful in suggesting or ruling out an approximate PMSI (postmortem submersion interval). For example, the time intervals required for certain growth phases of aquatic insects, such as caddisflies, that may attach themselves to the submerged remains can be used to estimate a minimum PMSI. Approximately 8 of the 13 orders of insects containing species with aquatic or semi-aquatic stages are likely to be associated with carrion or corpses in aquatic habitats. We present a case study in which portions of a body from an adult male were discovered in a south central Michigan stream. The body was dismembered and portions were recovered from two bags floating and submerged in the stream. Insect specimens collected from mesh and plastic bags consisted of one fly larva belonging to the family Muscidae, and caddisfly larvae belonging to two families: the Limnephilidae. (case-makers) and the Hydropsychidae, (net spinners). We used unique case-building behaviors of the limnephilid caddisflies found on the remains to elucidate a PMSI range consistent with the disappearance of the victim. It is important for forensic investigators to understand that although some precision is lost in estimating a PMSI with aquatic insects, these organisms should not be ignored in gathering evidence from aquatic crime scenes, and in fact, they can provide valuable details in estimating a PMSI.     

Collembola of the grave: a cold case history involving arthropods 28 years after death

This report describes a cold case in which a cadaver of a 28-year-old female was exhumed in February 2005 from a cemetery in Battle Creek, Michigan. She had sustained a gunshot wound to the head and was found dead in her home on November 15, 1977. The body of the victim was subsequently embalmed and then buried at a depth of 1.8 m in an unsealed casket that was placed inside an unsealed cement vault. The exhumation yielded thousands of live specimens of a single species of the order Collembola or spring tails, Sinella (Coecobrya) tenebricosa (Entomobryidae). This species is considered to be a "tramp" species, cosmopolitan in the United States and Canada. Due to the ideal environmental conditions at the site, the population of this species underwent growth and development inside the casket for a number of years. Collected with the Collembola were large numbers of Acarina (mites) of the Family Glycyphagidae, and fly puparia, Conicera tibialis Schmitz (Order: Diptera, Family: Phoridae), also known as coffin flies. These invertebrates are sometimes mentioned by forensic investigators as occurring on corpses in graves, but aspects of their life history are rarely described. The species of Collembola that was found surviving and reproducing on this corpse in a casket exhumed after 28 years was the oldest reported grave site occurrence for any collembolan species based on a survey of the literature back to 1898.     

Institutional constraints on cabinet formation: Veto points and party system dynamics

Research on government formation in parliamentary democracies has presented contradicting evidence on the role of political veto institutions and parliamentary polarization on the formation of cabinet types. Institutional rules may either provide significant leeway for political parties or seriously constrain them when forming sustainable coalitions. In contrast to previous studies we argue that the effect of political institutions is conditional on the degree of polarization in parliament. We test our hypotheses using original data on 842 cabinet formations in 33 advanced democracies between 1945–2018. In line with previous research, we find that the institutional rules have a pronounced effect on the type of cabinet formed, but that institutional rules moderate the effect of party system polarization. Thus, our findings provide important new insights on cabinet formation which are particularly relevant for today's increasingly polarized parliaments.