Institute of Forensic Medicine, Kennedyallee 104, 60596 Frankfurt am Main, Germany.
Forensic Sci Int. 2012 Sep 10;221(1-3):65-9. doi: 10.1016/j.forsciint.2012.04.001. Epub 2012 May 1.
By estimating the age of the immature stages of flies developing on a corpse, forensic entomologists are able to establish the minimum post-mortem interval. Blowflies, which are the first and most important colonizers, usually leave the cadaver at the end of the last larval stage searching for a pupation site. This period of development is referred as the post-feeding or wandering stage. The characteristics of the ground where the corpse was placed might be of notable importance for the post-feeding dispersal time: For pupariation the larvae prefer an environment protected from light and predators and may have a longer dispersal time in order to reach an appropriate pupation site. Hence, the dispersal time can vary and may influence the total time of development which may lead to an erroneous calculation of the post-mortem interval. This study investigates the effect of various post-feeding time intervals on the development of the blowfly Lucilia sericata at a temperature of 25°C. As larvae reached the post-feeding stage a pupariation substrate was offered at 0 and after 12, 24 and 48h. Only the larvae with a dispersal time of 24h (total time of development 325.2h; median) and 48h (total time of development 347.7h; median) showed a significantly longer total development time compared to the control group (total time of development 318.4h; median). The mortality rate did not differ between groups; however the flies that emerged from the group with a dispersal of 48h were significantly smaller indicating increased energy consumption during dispersal. The results of this study indicate that a prolonged post-feeding stage could increase the total developmental time of L. sericata which should be taken into consideration when interpreting entomological findings. The need for a serious examination of current rearing practices in forensic entomology laboratories is indicated because reference data sets for the time of development are usually produced by offering the post-feeding stage a substrate for pupariation immediately.
通过估计在尸体上发育的蝇类未成熟阶段的年龄，法医昆虫学家能够确定最小的死后间隔时间。第一且最重要的定居者——丽蝇，通常在最后一个幼虫阶段结束时离开尸体，寻找化蛹地点。这个发育阶段被称为取食后或漫游阶段。尸体放置地点的地面特征可能对取食后扩散时间有重要影响：对于化蛹，幼虫更喜欢避光和免受捕食者侵害的环境，并且可能需要更长的扩散时间才能到达合适的化蛹地点。因此，扩散时间可能会有所不同，并可能影响总发育时间，从而导致死后间隔时间的错误计算。本研究调查了在 25°C 温度下，不同取食后时间间隔对丝光绿蝇（Lucilia sericata）幼虫发育的影响。当幼虫进入取食后阶段时，在 0 小时和 12、24 和 48 小时后提供化蛹基质。只有扩散时间为 24 小时（总发育时间 325.2 小时；中位数）和 48 小时（总发育时间 347.7 小时；中位数）的幼虫总发育时间明显长于对照组（总发育时间 318.4 小时；中位数）。各组之间的死亡率没有差异；然而，从扩散 48 小时的组中出现的苍蝇明显更小，表明在扩散过程中消耗了更多的能量。本研究结果表明，取食后阶段的延长可能会增加丝光绿蝇的总发育时间，在解释昆虫学发现时应考虑到这一点。由于通常通过立即为取食后阶段提供化蛹基质来生成发育时间的参考数据集，因此有必要对法医昆虫学实验室中的当前饲养实践进行认真检查。
