The feeding habits of adult Brachycera are understudied and may provide important context for understanding invasive pest biology, as with the polyphagous small fruit pest Drosophila suzukii. We developed molecular methods to study adult D. suzukii gut content in order to understand its feeding habits. We designed and verified two primer pairs specific for either blueberries or blackberries and used a qPCR melt curve analysis to determine whether we can detect the presence or absence of berry feeding by adult flies. In a laboratory assay, the blueberry fly meal DNA can be detected for longer periods than the blackberry meal DNA. Generally, female gut contents are less variable than male gut contents. We also tested recently emerged flies that were not fed as adults but developed as larvae in either blueberries or blackberries. Some adult flies from each fruit had detectable fruit DNA in their gut, which could be due to pupal meconium feeding after emergence. Next, we aimed to test the primers in the field to develop techniques to track fruit feeding by D. suzukii in its natural field environment. First, to identify the most appropriate collection method, we determined how long we could detect fruit DNA, using previously developed primers within D. suzukii gut preserved in four types of trap fluid in the laboratory. The likelihood of detecting blackberry DNA differed by day, trap fluid, and between sexes. For the blueberry primer, the possibility of detecting blueberry DNA differed by trap fluid only. Based on those results, we used RV antifreeze with a Scentry SWD lure in field trials at two research station locations, one containing blackberries and one with blueberries. We established transects away from each fruit planting and collected up to 120 total flies at each point along transects. There were no significant differences in the number of flies containing berry DNA among collection points along the transect in both locations. These results suggest that adult flies move between crop and non-crop habitats and may not be highly dependent on fruit food resources.

中文翻译：

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在实验室饲养和野外捕获的成年果蝇（双翅目：果蝇科）内脏中检测水果粉

成年短角纲的摄食习性尚未得到充分研究，可能为了解侵入性害虫生物学提供重要的背景，如多食性小水果害虫 Drosophila suzukii。我们开发了分子方法来研究成年 D. suzukii 肠道含量，以了解其摄食习惯。我们设计并验证了两个特定于蓝莓或黑莓的引物对，并使用 qPCR 熔解曲线分析来确定我们是否可以检测到成年果蝇是否存在浆果喂养。在实验室检测中，蓝莓蝇粉 DNA 的检测时间比黑莓粉 DNA 的检测时间长。一般来说，雌性肠道内容物的可变性低于雄性肠道内容物。我们还测试了最近出现的苍蝇，这些苍蝇不是成虫喂养的，而是在蓝莓或黑莓中发育成幼虫。来自每个果实的一些成年果蝇在它们的肠道中具有可检测的果实 DNA，这可能是由于蛹在羽化后取食胎粪所致。接下来，我们旨在测试田间引物，以开发跟踪 D. suzukii 在自然田间环境中采食果实的技术。首先，为了确定最合适的收集方法，我们使用先前在实验室四种类型的捕集液中保存的铃木果蝇肠道内开发的引物，确定了我们可以检测水果 DNA 的时间。检测黑莓 DNA 的可能性因天、诱捕液和性别而异。对于蓝莓引物，检测蓝莓 DNA 的可能性仅因捕集液而异。基于这些结果，我们在两个研究站位置的现场试验中使用了带有 Scentry SWD 诱饵的 RV 防冻剂，一种含有黑莓，一种含有蓝莓。我们在远离每个水果种植区的地方建立了横断面，并在横断面的每个点收集了多达 120 只苍蝇。两个地点沿横断面的收集点之间含有浆果 DNA 的苍蝇数量没有显着差异。这些结果表明，成年果蝇在作物和非作物栖息地之间移动，可能不高度依赖水果食物资源。