Biomedical subjects

Donnah M Day

Publications and source records attributed to Donnah M Day.

3 recordsLinked to original sources

PubMed2006

A comparison of frozen/thawed and fresh food substrates in development of Calliphora augur (Diptera: Calliphoridae) larvae.

While research has examined the effect of freezing and subsequent thawing on the decomposition of carcasses, no studies have investigated the effect of the freezing and thawing of tissues used as a developmental substrate by fly larvae. This paper reports on the results of such a study using larvae of Calliphora augur (Fabricius) on sheep's liver. Approximately 20 first-instar larvae were collected on sheep liver and subsequently transferred to paired treatments of fresh and frozen/thawed liver equilibrated to room temperature. They were then left undisturbed for 1-10 days. When the allocated time had elapsed, the body length of the larvae in each pair of groups was compared. No significant differences were detected between any pairs at a 1% level and only one pair was significantly different at a 5% level. We conclude that freezing and thawing of a developmental medium of sheep's liver has no significant effect on growth of C. augur larvae.

Animals↗

PubMed2006

Influence of substrate tissue type on larval growth in Calliphora augur and Lucilia cuprina (Diptera: Calliphoridae).

The size of fly larvae is an important variable in the use of these insects to estimate postmortem interval. Furthermore, the nutritional intake of larvae is likely to vary subject to the part of a corpse on which they are feeding. A study was therefore conducted to investigate the effect of type of food substrate on larval growth in two species of forensically important Australian blowflies. After collection on sheep's liver in the laboratory, different groups of larvae of Lucilia cuprina (Wiedemann) and Calliphora augur (Fabricius) were grown on sheep's liver, meat, and brains, and their body lengths compared. Results indicated that the development of larvae fed sheep's liver was adversely affected compared with larvae fed meat and brain; they moulted later, reached maximum length more slowly and sometimes produced significantly smaller pupae. These findings, similar to those of another recent study, have obvious implications for postmortem interval determinations. Estimates may be considerably skewed if the site of collection of larvae at a death scene contains tissue types different to those used in reference experiments. We therefore recommend caution in forensic analyses that interpret crime scene data using developmental studies performed with a single type of larval food substrate.

Adipose Tissue↗

PubMed2005

Width as an alternative measurement to length for post-mortem interval estimations using Calliphora augur (Diptera: Calliphoridae) larvae.

The length of fly larvae collected from corpses is often used to help provide an entomological estimate of time since death. However, 'head-curling' by larvae can affect the accuracy of length measurements. To investigate a possible resolution to this problem, larvae of Calliphora augur were grown on sheep's liver at two constant temperatures (20 and 25 degrees C). Replicate samples were collected at set time intervals until pupation. Body length and width were measured for individual larvae and examined as predictors of age. It was found that body width, as measured at the junction of the fifth and sixth abdominal segments, is comparable with body length for age prediction of maggots of C. augur grown at these temperatures. Furthermore, conversion of width to length can be done with 95% accuracy from a simple linear model.

Animals↗