Aphids, mainly distributed in temperate zones, exhibit seasonal generation-alternating phenomena. Across the life cycle, different morphs are produced. Sitobion avenae (Fabricius 1775) is a major pest of wheat worldwide. To elucidate olfactory perception of morph-specific behavior across their life cycle, we investigated antennal sensilla among seven morphs using scanning electron microscopy. Trichoid, placoid, coeloconic, and campaniform sensilla were identified. Trichoid sensilla, big multiporous placoid sensilla (primary rhinarium), a group of sensilla (primary rhinaria), and campaniform sensilla showed similar distribution and resemblance among morphs, whereas small multiporous placoid sensilla (secondary rhinaria) exhibited obvious differences. Compared to apterous morphs, alate morphs possessed a greater abundance of secondary rhinaria, with the greatest found in males on antennal segments III-V. Alate virginoparae and alate sexuparae ranged from six to fourteen rhinaria on antennal segment III. Fundatrices, apterous virginoparae and apterous sexuparae only had one or two secondary rhinaria on antennal segment III while they disappeared in oviparae. Secondary rhinaria, lying in a cuticle cavity, are convex or concave in their central part. In males, both forms were present, with a greater proportion of convex form than that of the concave form. Fundatrices and virginoparae had the convex form while sexuparae had the concave form. Polyphenism of secondary rhinaria might suggest their association with the olfactory functions of morph-specific behavior. These results have improved our understanding of the adaptive evolution of the antennal sensilla in nonhost-alternating, holocyclic aphids.

中文翻译：

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非寄主交替全环 Sitobion avenae（半翅目：蚜科）不同成虫形态中触角感受器的多态性。

蚜虫主要分布于温带地区，表现出季节性的世代交替现象。在整个生命周期中，会产生不同的变形。Sitobion avenae (Fabricius 1775) 是全球小麦的主要害虫。为了阐明在整个生命周期中形态特异性行为的嗅觉感知，我们使用扫描电子显微镜研究了七种形态中的触角感受器。确定了毛状体、扁体、腔体和钟状感受器。毛状感受器、大多孔板状感受器(primary rhinarium)、一组感受器(primary rhinaria)和钟形感受器在变体间的分布和相似性相似，而小的多孔板状感受器(secondary rhinarium)表现出明显的差异。与无尾变体相比，alate morphs 具有更丰富的次生鼻，在触角节 III-V 上的男性中发现的最多。Alate virginoparae 和 alate sexuparae 在触角 III 段上的范围从 6 到 14 个 rhinaria。Fundatrices, apterous virginoparae 和 apterous sexuparae 仅在触角 III 节有 1 个或 2 个次生鼻，而在卵生中消失。次生鼻，位于角质腔内，中央部分呈凸形或凹形。在男性中，两种形式都存在，凸形的比例大于凹形的比例。Fundatrices和virginoparae具有凸形，而sexuparae具有凹形。次生鼻的多态性可能表明它们与形态特异性行为的嗅觉功能有关。这些结果提高了我们对非宿主交替中触角感受器自适应进化的理解，