Smith Joshua L, Palermo Nicholas A, Theobald Jamie C, Wells Jeffrey D
Department of Biological Sciences, Florida International University, 11200 SW 8th St, Miami, FL 33199, United States.
Department of Biological Sciences, Florida International University, 11200 SW 8th St, Miami, FL 33199, United States.
Forensic Sci Int. 2016 Sep;266:245-249. doi: 10.1016/j.forsciint.2016.06.004. Epub 2016 Jun 14.
One factor that influences estimates of time since death using entomological evidence is whether or not blow flies nocturnally oviposit. Field studies focusing on egg laying have found it occurs on an inconsistent basis. A key but poorly understood factor in nocturnal oviposition is a blow fly's ability to locate carrion under low light levels. It has been speculated that blow flies are more likely to walk than fly to carrion during the night, but this has not been empirically tested. We directly compared guided walking versus flying using infrared sensors under low light levels in laboratory conditions for Chrysomya megacephala (F.) (Diptera: Calliphoridae), a blow fly previously described to be nocturnal. We found C. megacephala is more likely to walk than fly toward carrion under low light levels (p=0.016). We did not, however, find differences between males and females for walking (p=0.48) or flying (p=0.42) despite male C. megacephala possessing eyes better suited for increased light capture. These results demonstrate the need to better understand where blow flies go at night, as bodies found within a fly's walking distance are more likely to be colonized.
利用昆虫学证据估计死亡时间时，一个影响因素是丽蝇是否在夜间产卵。专注于产卵情况的实地研究发现，其产卵情况并不稳定。夜间产卵的一个关键但尚未被充分理解的因素是丽蝇在低光照水平下定位腐肉的能力。据推测，丽蝇在夜间更有可能步行而非飞行前往腐肉，但这一点尚未得到实证检验。我们在实验室条件下，利用红外传感器，在低光照水平下直接比较了大头金蝇（Chrysomya megacephala (F.) ，双翅目：丽蝇科）的引导步行与飞行情况，此前曾描述这种丽蝇具有夜行性。我们发现，在低光照水平下，大头金蝇更有可能步行而非飞行前往腐肉（p = 0.016）。然而，尽管雄性大头金蝇的眼睛更适合在增加光照的情况下捕捉光线，但我们并未发现雄性和雌性在步行（p = 0.48）或飞行（p = 0.42）方面存在差异。这些结果表明，有必要更好地了解丽蝇夜间的去向，因为在丽蝇步行距离内发现的尸体更有可能被其寄生。
