Molecular analyses of DNA samples necessitate careful attention to experimental protocols to prevent contamination of samples during the specimen collection and DNA extraction, amplification, and visualisation stages. When these studies involve insects that are collected in the field, standard procedures require samples to be individually sorted and stored in single tubes to prevent cross-contamination of DNA between specimens. This additional step can be time consuming and impractical when the survey population is large. The focus of our study was to experimentally determine if this assumed contamination risk is valid and if it varies with storage conditions. To test this, we co-stored a single intact fruit fly (Drosophilia melanogaster) (Diptera: Drosophilidae) known to be infected with the bacterial endosymbiont Wolbachia (Anaplasmataceae) with uninfected flies in tubes for three-hour, 24-hour, and one-week durations. For each treatment time, replicates of five tubes contained one infected fly and either one or five uninfected flies (1:1 and 1:5 ratios). Overall, eight of 30 tubes had contamination regardless of storage duration, and storing samples in crowded (1:5 ratio) conditions significantly increased the risk of Wolbachia DNA transference. Our results suggest that researchers should make efforts to sample and store specimens individually if cross-contamination is a concern in molecular analyses.

DNA样品的分子分析需要仔细注意实验规程，以防止在样品收集以及DNA提取，扩增和可视化阶段污染样品。当这些研究涉及在现场收集的昆虫时，标准程序要求将样品单独分类并存储在单个试管中，以防止标本之间的DNA交叉污染。当调查人口很大时，此附加步骤可能很耗时且不切实际。我们研究的重点是通过实验确定这种假定的污染风险是否有效以及它是否随存储条件而变化。为了对此进行测试，我们共同存储了一个完整的果蝇（果蝇（Drosophilia melanogaster））（双翅目：果蝇科）已知已被感染的细菌内共生菌Wolbachia（Anaplasmataceae）感染，而未感染的蝇在试管中持续了3小时，24小时和1周。对于每个处理时间，五支试管的重复样本包含一只受感染的果蝇和一或五个未感染的果蝇（1：1和1：5的比例）。总体而言，无论储存时间长短，30个试管中有8个受到污染，并且在拥挤（比例为1：5）的条件下储存样品显着增加了Wolbachia DNA转移的风险。我们的结果表明，如果交叉污染是分子分析中关注的问题，那么研究人员应努力单独对样品进行取样和存储。