ABSTRACT
@#Development of insects in laboratory for minimum post mortem interval estimation (mPMI) or time of colonisation (TOC) in forensic entomology can be affected by the type and quality of food consumed during larval period. Since mPMI estimation also involves analysis of larval specimens collected from burned human remains, it is important to study if burned tissues could affect growth of sarcosaprophagous larvae. This study investigated the effect of burned tissues on the size and developmental period of Megaselia scalaris (Loew) (Diptera: Phoridae), a species of forensic importance. Development of M. scalaris on 75 g burned cow’s liver was compared with control liver in three study replicates. Mean larval length (2.87 ± 0.11 mm) and weight (0.81 ± 0.08 mg) of M. scalaris larvae in burned liver diets were significantly lower than larval length (5.03 ± 0.15 mm) and weight (2.85 ± 0.21 mg) of control liver diets (p < 0.001) whilst mean pupal length (2.53 ± 0.06 mm) and weight (0.92 ± 0.06 mg) in burned liver diets were significantly lower than pupal length (3.52 ± 0.06 mm) and weight (2.84 ± 0.16 mg) in control liver diets (p < 0.001). Development of larvae in burned liver was 5-9 hours slower than those feeding on control liver based on single observation. Although the assessment is preliminary, the findings indicate physical growth of larvae feeding on burned animal tissues was affected and entomological specimens recovered from burned remains should be evaluated carefully to avoid errors in mPMI/TOC estimation. Limitations and suggestions for further research are also presented herein.
ABSTRACT
The objective of this study was to evaluate the precision of the non linear models of Davidson (1942, 1944), Stinner et al. (1974), Sharpe & DeMichele (1977), and Lactin et al. (1995) to describe relationship between developmental rate of different stages of Podisus nigrispinus (Dallas) and temperature. Lower values of R² for the models of Davidson (0.1593 to 0.2672, and 0.1406 to 0.2804 for males and females, respectively) and of Stinner et al. (0.2136 to 0.6389, and 0.1417 to 0.3045 for males and females, respectively) showed that these models were not adequate to estimate developmental rate of P. nigrispinus as function of temperature. However, high values of R² for the models of Sharpe & DeMichele (0.9226 to 0.9893, and 0.8818 to 0.9914 for males and females, respectively), and of Lactin et al. (0.9485 to 0.9997, and 0.8961 to 0.9997 for males and females, respectively) showed that these models are suitable to estimate developmental rate of P. nigrispinus as function of temperature. Females of P. nigrispinus showed high tolerance to high temperature which is represented by high values of H H for immature stage of this insect obtained with the Sharpe & DeMichele model. According to this model females of P. nigrispinus present thermal stress at 33.3°C, which indicates that maximum thermal estimated by this model was close to the real one.
O objetivo deste estudo foi avaliar a precisão dos modelos não lineares de Davidson (1942, 1944), Stinner et al. (1974), Sharpe & DeMichele (1977) e Lactin et al. (1995) no estudo da relação entre as taxas de desenvolvimento das diferentes fases de Podisus nigrispinus (Dallas) e a temperatura. Os menores valores de R² para os modelos de Davidson (0,1593 a 0,2672, e de 0,1406 a 0,2804 para machos e fêmeas, respectivamente) e de Stinner et al. (0,2136 a 0,6389, e de 0,1417 a 0,3045 para machos e fêmeas, respectivamente), indicaram que esses modelos não são adequados para a estimativa do tempo de desenvolvimento de P. nigrispinus, em função da temperatura. Entretanto, os altos valores de R² para os modelos de Sharpe & DeMichele (0,9226 a 0,9893, e de 0,8818 a 0,9914 para machos e fêmeas, respectivamente), e de Lactin et al. (0,9485 a 0,9997, e de 0,8961 a 0,9997 para machos e fêmeas, respectivamente), indicaram que esses modelos são adequados para a estimativa do tempo de desenvolvimento de P. nigrispinus, em função da temperatura. Fêmeas de P. nigrispinus, na fase imatura, mostraram maior tolerância à alta temperatura, a qual é representada pelo parâmetro H H obtido do modelo de Sharpe & DeMichele. De acordo com este modelo, fêmeas de P. nigrispinus na fase imatura apresentam estresse térmico a 33,3°C, indicando que a estimativa da ação térmica máxima foi bastante realista.