Diatoms in maggots; a potential tool for drowning diagnosis - A preliminary study

Area of Science:

• Forensic Science
• Environmental Science
• Biology

Background:

• Advanced decomposition significantly hinders the reliability of the diatom test in drowning investigations due to soft tissue loss.
• Carrion insect larvae, particularly blowfly maggots, consume decomposed tissues, presenting a potential alternative source for diatom analysis.
• Establishing the utility of diatom testing in maggots is crucial for improving drowning investigations in severely decomposed cases.

Purpose of the Study:

• To determine the effectiveness of the diatom test in carrion insect larvae for identifying drowning in severely decomposed bodies.
• To investigate the presence and types of diatoms in maggots feeding on drowned animal carcasses.

Main Methods:

• A modified acid digestion method using nitric acid, K2Cr2O7, and HCl was employed to process blowfly larvae.
• Larvae were collected from piglet carcasses that had been experimentally drowned in freshwater and seawater.
• Extracted diatoms were analyzed and characterized using light microscopy and digital imaging.

Main Results:

• Diatoms recovered from maggots on seawater-drowned piglets matched diatoms found in the seawater drowning medium.
• Centric diatoms (200 ± 60 diatoms/mL) were more abundant than pennate diatoms (80 ± 20 diatoms/mL) in maggots from sea-drowned piglets.
• Common diatom species identified in both maggots and water samples included Coscinodiscus sp. and Navicular spp.; no diatoms were found in maggots from freshwater-drowned piglets.

Conclusions:

• The diatom test remains a reliable diagnostic tool for determining drowning, even in fully decomposed bodies, by analyzing associated insect larvae.
• This study is the first to isolate diatoms from maggots feeding on drowned bodies, validating their use in forensic entomology.
• The findings support further research into the application of maggots for confirming drowning in forensic investigations.