Department of Parasitology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
Vector Biology and Vector Borne Diseases Research Unit, Department of Parasitology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
PLoS One. 2022 Feb 25;17(2):e0263268. doi: 10.1371/journal.pone.0263268. eCollection 2022.
Morphological characteristics of eggshells are important in sand fly ootaxonomy. In this study, eggshells from Phlebotomus stantoni Newstead, Sergentomyia khawi (Raynal), and Grassomyia indica (Theodor) sand flies collected in Chiang Mai province, Thailand were examined and characterized using light microscopy (LM) and scanning electron microscopy (SEM). Then, eggshell morphology of these three species was described for the first time. Each gravid female was forced to lay eggs by decapitation and the eggs were collected for SEM analysis. Egg laying females were identified by morphological examination and molecular typing using cytochrome b (Cytb) as a molecular marker. The chorionic sculpturing of Ph. stantoni eggs combines two patterns on the same egg: unconnected parallel ridges and reticular patterns. Sergentomyia khawi and Gr. indica have similar chorionic polygonal patterns, but their exochorionic morphology and aeropylar area are different. Results indicate that eggshell morphological characteristics such as chorionic pattern, exochorionic morphology, inter-ridge/boundary area, aeropylar area (including the number of aeropyles) and basal layer, can be useful to develop morphological identification keys of eggs. These can serve as an additional tool to distinguish species of sand flies. In addition, the chorionic sculpturing of the eggs of the three species of sand flies observed by LM is useful for species identification in gravid females with spermathecae obscured by eggs.
卵壳的形态特征在白蛉分类学中很重要。本研究使用光学显微镜（LM）和扫描电子显微镜（SEM）检查和描述了来自泰国清迈省的斯氏按蚊、卡氏白蛉和印度库蚊的卵壳，并首次描述了这三个物种的卵壳形态。通过断头强迫每只怀孕雌蚊产卵，并收集卵进行 SEM 分析。通过形态学检查和以细胞色素 b（Cytb）作为分子标记的分子分型来鉴定产卵雌蚊。斯氏按蚊卵的绒毛层结构在同一卵上结合了两种模式：不相连的平行脊和网状图案。塞氏白蛉和印度库蚊具有相似的绒毛多边形模式，但它们的外绒毛形态和呼吸孔区不同。结果表明，卵壳形态特征，如绒毛层模式、外绒毛形态、脊间/边界区域、呼吸孔区（包括呼吸孔的数量）和基底层，可以用于开发卵的形态识别特征。这些可以作为区分白蛉种的附加工具。此外，通过 LM 观察到的这三种白蛉卵的绒毛层结构对于被卵掩盖的受精囊的怀孕雌蚊的物种鉴定很有用。
