Influence of Substrate Tissue Type on Larval Growth in Calliphora augur and Lucilia cuprina (Diptera: Calliphoridae)^*

Abstract

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.

Effect of temperature on development of the blowfly, Lucilia cuprina (Wiedemann) (Diptera: Calliphoridae)

“…For all four developmental events, the thermal accumulation values from Day and Wallman fell outside the 95% confidence intervals of the models calculated using medians in this study. The minimum values reported by Day and Wallman [17] fell within the confidence intervals for the models derived in this study for minimum time to reach wandering and pupation, but fell outside the confidence intervals of the models for first and second ecdysis. Even though the minimum time taken to reach post-feeding stages show similar developmental thresholds, the differences noted in the earlier instars may be attributed to variation in development rates in blowfly populations at different latitudinal and altitudinal ranges [7].…”

“…These conditions, combined with the low humidity and high risk of desiccation, may have affected the time that post-feeding larvae spent searching for a suitable site to pupate and, if no suitable site was found, may also have contributed to the high mortality rate noted, especially when higher temperatures imposed additional physiological stress. Day and Wallman [17] reported that at 24°C, L. cuprina took an average time of 48 h to reach first ecdysis, 72h to reach second ecdysis, 96h to begin wandering, and 144 h to begin pupation. These values vary from those obtained in this study, which showed that at 24°C, larvae took on average 26.2h to reach first ecdysis, 56.2h to reach second ecdysis, 105.6h to begin wandering, and 165.0h to begin pupation.…”

“…Lucilia cuprina (Wiedemann) (Diptera: Calliphoridae) is a blowfly that causes myiasis in humans and livestock, usually sheep [10,11], and is commonly found around garbage and decaying flesh [2]. As such, L. cuprina has medical, veterinary, agricultural, public health, and forensic significance [12][13][14][15][16], but there are few published data on the postembryonic development of this species [10,[16][17][18], with most applied studies focusing on the effect of L. cuprina on sheep production. L. cuprina is closely related to L. sericata, another forensically important species with which it may be confused due to very similar morphology [19,20].…”

Light-Induced Variability in Development of Forensically Important Blow FlyPhormia regina(Diptera: Calliphoridae)

“…This is largely from a lack of attention to ßaws in design (e.g., pseudoreplication and inaccurate temperature measurement) of temperature-controlled larval rearing (Nabity et al 2006). Several potential sources of error have previously been addressed: pupal handling (Ash andGreenberg 1975, Anderson 2000), maggot mass temperatures (Greenberg 1991), larval substrate (Clark et al 2006, Day andWallman 2006), and constant versus ßuctuating temperatures Allen 2001, Clarkson et al 2004). However, there are many more areas of concern, such as experimental design/units, temperature measurement, photoperiod, and relative humidity.…”

Effect of preservative solutions on preservation of Calliphora augur and Lucilia cuprina larvae (Diptera: Calliphoridae) with implications for post-mortem interval estimates

“…Separate cages containing gravid females and males of each species were presented with a portion of sheep's liver that had been frozen, thawed and equilibrated to room temperature [50,51]. The females were given 1 h to oviposit or larviposit.…”