This study aimed to characterize and correlate the stylet penetration behaviors of nymphs of the Neotropical brown stink bug, Euschistus heros (F.), on immature soybean pods. Waveforms were obtained using electropenetrography (EPG). The findings revealed that the nymphs exploited the xylem vessels and the seed tegument or endosperm. Primarily 4 phases were characterized: nonfeeding, pathway, salivation, and ingestion. The waveforms of each phase were similar in appearance across instars. The biological meanings of waveforms were based on visual observations, comparison with waveforms of adults, and histological studies. Np represents the insect resting or walking on soybean pod surface. Eh1 represents the first contact between the mouthparts (stylets) and plant tissue. Eh2 represents xylem sap ingestion, and Eh3 represents seed activities (including tegument and endosperm). The number of waveform events did not differ among instars for all waveforms. However, for Eh3, fifth instars performed more activities than other instars. The second instars had the smallest value, and third and fourth instars had intermediate values. For total duration, all waveforms differed among instars. Np duration was shorter for third compared with second and fourth instars and intermediate for fifth instar. For Eh1, second and third instars had the longest duration (1.5× to 2× greater) compared with fourth and fifth instars. For Eh2 and Eh3, the second-instar showed the longest (~2× greater) and shortest durations, respectively. Overall, this study provides important insights into the feeding behavior of E. heros nymphs so that effective pest management programs can be developed to contain this pest.

中文翻译：

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大豆荚不同部位取食的英雄大豆（F.）（异翅目：蝽科）若虫的电渗透描记法研究

本研究旨在描述新热带褐蝽（Euschistus Heros，F.）若虫对未成熟大豆豆荚的探针穿透行为并进行关联。使用渗透电图（EPG）获得波形。研究结果表明，若虫利用木质部导管和种子外皮或胚乳。主要分为 4 个阶段：不进食、途径、流涎和摄取。各个龄期的每个阶段的波形在外观上都相似。波形的生物学意义基于视觉观察、与成人波形的比较以及组织学研究。Np代表在豆荚表面休息或行走的昆虫。Eh1 代表口器（管心针）和植物组织之间的第一次接触。Eh2代表木质部汁液摄入，Eh3代表种子活性（包括外皮和胚乳）。对于所有波形，波形事件的数量在不同龄期之间没有差异。然而，对于 Eh3，第五龄虫比其他龄虫进行更多的活动。第二龄的值最小，第三龄和第四龄的值居中。对于总持续时间，所有波形在不同龄期之间都不同。与第二龄和第四龄相比，第三龄的 Np 持续时间较短，第五龄的 Np 持续时间较短。对于 Eh1，与第四龄和第五龄相比，第二龄和第三龄的持续时间最长（长 1.5 倍至 2 倍）。对于 Eh2 和 Eh3，第二龄分别表现出最长（约 2 倍）和最短的持续时间。总的来说，这项研究为英雄若虫的摄食行为提供了重要的见解，以便制定有效的害虫管理计划来遏制这种害虫。