胡萝卜微管蚜是重要药用植物金银花的优势害虫，在金银花采收期高发，严重影响药材产量和品质。胡萝卜微管蚜是寄主转换型蚜虫，在金银花上越冬后，春季在其抽捎现蕾期爆发成灾，春末夏初金银花开花期后则迁飞到夏季寄主，其离开原生寄主金银花的机制尚不明确。鉴于该蚜虫主要在金银花叶片背面取食，以及抽捎期叶片是幼嫩状态、开花期叶片是成熟状态，推测金银花叶片的正背面和发育阶段是影响胡萝卜微管蚜取食行为及寄主选择的重要原因。为明确胡萝卜微管蚜在金银花叶片上的取食行为时空差异及机制，本研究利用刺吸电位图谱技术（electrical penetration graph，EPG）先探究了金银花叶片正面和背面形态结构差异对胡萝卜微管蚜取食行为的影响；在此基础上对胡萝卜微管蚜在金银花叶片不同发育阶段（幼嫩叶片：15 d 叶龄叶片；成熟叶片：30 d 叶龄叶片）的取食行为差异进行研究；再通过石蜡切片法和代谢组学技术分析比较幼嫩和成熟金银花叶片的内部结构和韧皮部汁液化学成分，从而揭示金银花叶片不同发育阶段对胡萝卜微管蚜取食行为的影响，为阐释胡萝卜微管蚜寄主转换机制及其科学防控提供理论依据。主要结果如下：

1.明确了胡萝卜微管蚜在金银花叶片的取食波形和阶段

根据口针穿刺路径的振幅和频率不同，胡萝卜微管蚜成虫在金银花叶片上刺探取食的EPG波形可分为np、C(A+B+C)、pd、F、E1、E2、G波7个波形，可分为蚜虫口针未刺探阶段（非刺探np波）、韧皮部之前的刺探路径阶段（刺探路径C（pd）波、机械障碍F波）、韧皮部阶段（分泌唾液E1波和韧皮部汁液吸食E2波）和木质部阶段（水分吸食G波）4个阶段。

2.明确了胡萝卜微管蚜在金银花叶片正面和背面的取食行为差异与机制

胡萝卜微管蚜叶片正面取食的非刺探波（np波）的总持续时间显著高于背面，是背面的2.03倍；在背面取食时口针在韧皮部分泌唾液波（E1波）、吸食汁液波（E2波）和木质部吸食水分波（G波）的出现概率分别为正面的2.00、2.25和1.29倍，其中E1波和G波的总持续时间显著高于正面（P＜0.05），是正面的3.24和2.00倍，而E2波的总持续时间在正面和背面无显著差异。进一步对金银花叶正背面的外部形态和解剖结构进行研究，发现金银花正面较背面颜色深、光滑、蜡质层厚。金银花叶片的组织结构从正面到背面依次包括上表皮，栅栏组织，海绵组织和下表皮。其中金银花叶表面上角质层的厚度（3.15±0.08 µm）显著高于下角质层（1.72±0.07 µm）（P＜0.05）。猜测金银花叶片上角质层影响了胡萝卜微管蚜在金银花叶正面的取食。

3.揭示了胡萝卜微管蚜在幼嫩和成熟叶片上的取食行为差异与机制

EPG结果表明，刺探路径阶段，胡萝卜微管蚜在成熟叶片上刺吸时机械障碍F波的出现概率（44.00±10.13%）是幼嫩叶片（20.00%±0.00%）的2.20倍。且胡萝卜微管蚜在成熟叶片上刺吸时F波的次数（1.36±0.38）是幼嫩叶片（0.21±0.09）的6.48倍（P＜0.05），说明成熟叶片内部存在物理抗性因子；韧皮部阶段，胡萝卜微管蚜取食幼嫩叶片E2波的总持续时间（63.54±16.69 min）是成熟叶片（10.86±5.27 min）的5.85倍（P＜0.05），猜测成熟叶片韧皮部汁液中存在化学抗性因子影响胡萝卜蚜的取食行为。

金银花叶片解剖结构结果表明，成熟叶片的厚度（136.96±10.13 μm）显著高于幼嫩叶片，且成熟叶片的上角质层厚度（1.92±0.16 μm）和下角质层厚度（1.56±0.08 μm）均显著高于幼嫩叶片（P＜0.05）。鉴于胡萝卜微管蚜在金银花叶片背面为害，所以猜测推测叶片的角质层影响了胡萝卜微管蚜的刺探。

金银花叶片韧皮部汁液化学成分分析结果表明，在幼嫩和成熟叶片韧皮部汁液中共鉴定了1310个代谢物，其中幼嫩vs成熟处理组的差异代谢物总数为340个，其中成熟组上调的代谢物为174个，下调的代谢物为168个。利用KEGG数据库对差异代谢物进行注释，发现相比于幼嫩叶片，成熟叶片中淀粉和蔗糖代谢、果糖和甘露糖代谢、戊糖磷酸途径等糖类代谢通路上调，而苯丙氨酸、酪氨酸和色氨酸生物合成等通路下调。猜测可能是淀粉和蔗糖代谢等通路上调导致韧皮部内可溶性糖浓度高，蚜虫体内渗透势升高引起蚜虫脱水，并且苯丙氨酸、酪氨酸和色氨酸生物合成通路下调影响了相关氨基酸的浓度，从而影响了蚜虫吸食能量来生存繁殖。

本文研究了胡萝卜微管蚜的取食行为偏好及机制，为阐释胡萝卜微管蚜寄主转换机制及其科学防控提供理论依据。

Semiaphis heraclei is a dominant pest of the important medicinal plant honeysuckle, and it is particularly prevalent during the harvest period of honeysuckle, severely affecting the yield and quality of the medicinal material. S. heraclei is a host-alternating aphid species. After overwintering on honeysuckle, it becomes a pest during the shoot elongation and bud formation stages in spring. After the flowering period of honeysuckle in late spring and early summer, the aphids migrate to their summer hosts. The mechanism by which they leave their primary host, honeysuckle, is still unclear. Given that this aphid mainly feeds on the underside of honeysuckle leaves, and considering that the leaves are in a tender state during the shoot elongation stage and in a mature state during the flowering stage, it is speculated that the leaf surface (adaxial vs. abaxial) and developmental stage of honeysuckle leaves are important factors influencing the feeding behavior and host selection of S. heraclei. To clarify the temporal and spatial differences in the feeding behavior of S. heraclei on honeysuckle leaves and the underlying mechanisms, this study first used electrical penetration graph (EPG) technology to investigate the effects of the morphological and structural differences between the adaxial and abaxial surfaces of honeysuckle leaves on the feeding behavior of S. heraclei. Based on this, the study further examined the differences in feeding behavior of S. heraclei on honeysuckle leaves at different developmental stages (tender leaves: 15-day-old leaves; mature leaves: 30-day-old leaves). Finally, paraffin sectioning and metabolomics techniques were used to analyze and compare the internal structure and phloem sap chemical composition of tender and mature honeysuckle leaves, thereby revealing the impact of different developmental stages of honeysuckle leaves on the feeding behavior of S. heraclei, providing a theoretical basis for elucidating the host-alternating mechanism of S. heraclei and its scientific control. The main results are as follows:

1.Clarified the feeding waveforms and stages of Semiaphis heraclei on honeysuckle leaves

Based on the amplitude and frequency of the stylet penetration paths, the EPG waveforms of adult S. heracleis feeding on honeysuckle leaves can be divided into seven types: np, C(A+B+C), pd, F, E1, E2, and G waves. These can be categorized into four stages: non-probing stage (np wave), probing stage before reaching the phloem (pathway C (pd) wave, mechanical barrier F wave), phloem stage (saliva secretion E1 wave and phloem sap ingestion E2 wave), and xylem stage (water ingestion G wave).

2.Clarified the differences and mechanisms in feeding behavior of Semiaphis heraclei on the adaxial and abaxial surfaces of honeysuckle leaves 

The total duration of non-probing (np) waves during feeding on the adaxial surface was significantly higher than that on the abaxial surface, being 2.03 times longer. When feeding on the abaxial surface, the occurrence probabilities of the stylet salivation wave (E1 wave), phloem sap ingestion wave (E2 wave), and xylem water ingestion wave (G wave) were 2.00, 2.25, and 1.29 times higher than those on the adaxial surface, respectively. The total durations of E1 and G waves were significantly longer on the abaxial surface than on the adaxial surface (P < 0.05), being 3.24 and 2.00 times longer, respectively, while the total duration of E2 wave showed no significant difference between the two surfaces. Further studies on the external morphology and anatomical structure of the adaxial and abaxial surfaces of honeysuckle leaves revealed that the adaxial surface was darker, smoother, and had a thicker wax layer compared to the abaxial surface. The leaf tissue structure of honeysuckle, from the adaxial to the abaxial surface, consists of the upper epidermis, palisade tissue, spongy tissue, and lower epidermis. The thickness of the upper cuticle (3.15 ± 0.08 µm) was significantly higher than that of the lower cuticle (1.72 ± 0.07 µm) (P < 0.05). It is speculated that the upper cuticle of honeysuckle leaves affects the feeding behavior of S. heraclei on the adaxial surface.

3.Revealed the differences and mechanisms in feeding behavior of Semiaphis heraclei on tender and mature leaves 

EPG results showed that during the probing stage, the occurrence probability of the mechanical barrier F wave during probing on mature leaves (44.00 ± 10.13%) was 2.20 times higher than that on tender leaves (20.00% ± 0.00%). The number of F waves during probing on mature leaves (1.36 ± 0.38) was 6.48 times higher than that on tender leaves (0.21 ± 0.09) (P < 0.05), indicating the presence of physical resistance factors in mature leaves. During the phloem stage, the total duration of E2 waves when feeding on tender leaves (63.54 ± 16.69 min) was 5.85 times longer than that on mature leaves (10.86 ± 5.27 min) (P < 0.05), suggesting that chemical resistance factors in the phloem sap of mature leaves affect the feeding behavior of S. heraclei.

The anatomical structure results of honeysuckle leaves showed that the thickness of mature leaves (136.96 ± 10.13 µm) was significantly higher than that of tender leaves, and the thicknesses of the upper and lower cuticles of mature leaves (1.92 ± 0.16 µm and 1.56 ± 0.08 µm, respectively) were also significantly higher than those of tender leaves (P < 0.05). Given that S. heraclei mainly feeds on the underside of honeysuckle leaves, it is speculated that the leaf cuticle affects the probing behavior of S. heraclei.

The chemical composition analysis of phloem sap from honeysuckle leaves revealed a total of 1310 metabolites in the phloem sap of tender and mature leaves, with 340 differential metabolites between the tender and mature treatment groups. Among these, 174 metabolites were upregulated and 168 were downregulated in mature leaves. Annotation of differential metabolites using the KEGG database showed that compared with tender leaves, metabolic pathways such as starch and sucrose metabolism, fructose and mannose metabolism, and pentose phosphate pathway were upregulated in mature leaves, while pathways such as phenylalanine, tyrosine, and tryptophan biosynthesis were downregulated. It is speculated that the upregulation of starch and sucrose metabolism pathways may lead to higher concentrations of soluble sugars in the phloem, causing an increase in the osmotic potential within the aphid's body, leading to dehydration of the aphid. Additionally, the downregulation of phenylalanine, tyrosine, and tryptophan biosynthesis pathways may affect the concentration of related amino acids, thereby influencing the aphid's feeding energy for survival and reproduction.

This study investigated the feeding behavior preferences and mechanisms of S. heraclei, providing a theoretical basis for elucidating the host-alternating mechanism of S. heraclei and its scientific control.