Postfeeding Larval Dispersal Behavior of Late Season Blow Flies (Calliphoridae) in Southern Ontario,Canada

Postfeeding dispersal involves migration of larvae away from their food source in order to pupate. Puparia are difficult to find, yet are important for estimating PMI, and missing puparia during collection can result in inaccurate estimations. This study investigates the late season maggot dispersal patterns for blow flies at coyote carcasses in two habitats with an aim to improving puparia collection procedures. Puparia samples collected from various dispersal distances and directions tested the spatial distribution patterns of the various species using the variance/mean ratio (VMR). Lucilia illustris was the most common species to emerge, with a preferred minimum dispersal distance of more than 50.8 cm and an overall VMR value of 14.91, indicating this species had a clumped distribution pattern. These findings highlight that current collection procedures that use random sampling from under carcasses do not adequately account for the spatial distribution of larvae.     

广东省室内、室外及中毒死亡案件中法医昆虫学的应用报道

基于昆虫的死亡时间推断是目前最为有效和最准确的方法,本文介绍了广东省4例应用昆虫准确判断死亡时间的案例,这些案例分别发生于3月、5月和6月,现场包括室外现场和室内现场,尸体类型包括死亡不久的尸体和高度腐败的尸体,死亡原因包括钝器窒息、锐器致死、勒颈致死及过量药物中毒致死,其中过量药物中毒致死的案例由于体内含有49倍致死剂量的氯氮平从而使昆虫的发育受到严重影响进一步使得死亡时间推断时间结果比真实时间短。     

Blowfly Larval Tissues as a Secondary Detector for Determining Paraquat-Related Death in Rabbit Carcass

Paraquat poisoning is commonly associated with suicide or homicide in Malaysia. In a case involving advanced body decomposition, pathological analysis regarding the cause of death may become difficult or almost impossible. Insects serve as common alternative matrix for poison detection in forensic analysis. Paraquat detection via secondary bioaccumulation in fly larvae tissue has never been reported. In this study, tissues from blowfly larvae collected from a rabbit carcass with paraquat poisoning were analyzed for secondary bioaccumulation. Larvae samples were collected and analyzed using liquid–liquid extraction. The detection was performed via reduction of quaternary ammonium presence in paraquat and analyzed using gas chromatography–mass spectrometry (GC-MS) with selected ion monitoring mode (SIM mode). GC-MS showed the elution of reduced paraquat was at retention time 12.8 min. Blowfly larvae tissue has proven useful as a secondary detector in paraquat-related deaths.     

Quantifying the Temperature of Maggot Masses and its Relationship to Decomposition

Numerous Calliphoridae species have been observed to form larval aggregations during the feeding stage of development, resulting in localized increases in temperature. This study investigates the relationship between maggot numbers in a mass and heat generation. Single‐species aggregations (Lucilia sericata) of various sizes (50–2500 individuals) were reared in the laboratory at a constant ambient temperature of 22°C. Internal mass temperatures were recorded every 5 min throughout the feeding stage of development. Results showed that mass temperatures increased with mass numbers (p‐value < 0.001), ranging from 2.5 to 14°C above ambient. A minimum mass size of 1200 produced overall temperatures that were significantly warmer than ambient, diverging away from 22°C after c. 26 h. These results indicate that the microclimate of a mass has the potential to differ significantly from ambient, which may be influencing larval development rates and should therefore be factored into mPMI estimates to increase accuracy.