Department of Biology, Loyola University Maryland, Baltimore, MD 21210, USA.
Forensic Studies Program, Loyola University Maryland, Baltimore, MD 21210, USA.
J Med Entomol. 2021 Jul 16;58(4):1663-1672. doi: 10.1093/jme/tjab029.
Foraging by Calliphora vicina Robineau-Desvoidy often leads to a period of bubbling behavior, followed by either deposition of the regurgitate onto surfaces or reuptake of the bubble. Eventually, the partially or undigested food is passed in the excreta forming fecal or defecatory stains on surfaces in which deposition occurs. This study examined the digestive artifacts (i.e., regurgitate and defecatory stains) formed following consumption of human blood and semen by adult flies in an attempt to determine the length of time the meal was retained in the crop. The morphological appearance of either type of stain appeared consistent with the color of blood or semen for 10-20 d after feeding. When tested with ABA Hematrace immunochromatographic strip assays, blood was detectable in at least 33% of fly artifacts 25 d after the initial consumption of blood. Similarly, semen was detected in nearly 34% of digestive artifacts 30 d after feeding on human semen when using ABA p30 cards. Human body fluids were also detected in fly artifacts when using RSID lateral flow assays, but a much lower percentage of artifacts tested positive for blood (4.9%) and semen (4.6%) 25-d postfeeding in comparison to ABA strip assays. The difference between the types of lateral flow assays appeared to be due to extraction efficiencies of the buffers used for isolation of blood or semen from the fly artifacts. The implications of these observations in reference to seasonal adaptations and to bloodstain pattern analysis at crime scenes are discussed.
麻蝇（Calliphora vicina Robineau-Desvoidy）在觅食时常会出现冒泡行为，之后会将反刍物吐出或再次吞下。最终，部分或未消化的食物会随粪便排出，在沉积发生的表面形成粪便或排泄斑。本研究通过观察成年蝇在进食人血和精液后的消化痕迹（即反刍物和排泄斑），试图确定食物在胃中停留的时间。这两种痕迹的形态外观在进食后 10-20 天内与血液或精液的颜色一致。在用 ABA Hematrace 免疫层析条进行检测时，在最初进食血液后 25 天，至少有 33%的蝇消化痕迹中仍能检测到血液。类似地，在用 ABA p30 卡进行检测时，在进食人精液后 30 天，近 34%的消化痕迹中可检测到精液。使用 RSID 侧向流动检测也可以在蝇消化痕迹中检测到人体体液，但与 ABA 条检测相比，血液（4.9%）和精液（4.6%）阳性的痕迹比例要低得多，在进食后 25 天进行检测时。两种侧向流动检测类型之间的差异似乎是由于用于从蝇消化痕迹中分离血液或精液的缓冲液的提取效率不同所致。这些观察结果对季节性适应和犯罪现场血迹模式分析的意义将在文中讨论。
