To clarify the types, number, and distribution of sensilla on the head of the fifth instar Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae) larvae and identify the main sensilla of azadirachtin acting on larvae, scanning electron microscopy was used to study the morphology of the head and sensilla on the mouthparts. The four sensilla—sensillum basiconicum, sensillum chaeticum, sensillum styloconicum, and sensillum trichodeum—on the head of the fifth instar larvae were treated with 0, 0.1, 0.5, 1, 2, and 4 mg/kg azadirachtin by a microdrop method. The larvae showed an obvious antifeeding effect with azadirachtin. And higher the concentration of azadirachtin, the more obvious the phenomenon of antifeeding activity. The sensillum styloconicum and the sensillum trichodeum were the main sensilla for azadirachtin. When 1 mg/kg azadirachtin was used to treat sensillum styloconicum and sensillum basiconicum, the fifth instar larvae of S. litura showed obvious antifeedant activity and the cumulative feed intake for 24 hr was no more than 30% of the leaf area. Quantitative reverse‐transcription polymerase chain reaction verified the expression patterns of some Grs, indicating that Grst43a was upregulated by 1.3‐ and 3.9‐fold, Gor24 was upregulated by 2.5‐ and 3.3‐fold, Gr5a was downregulated by 0.6‐fold and upregulated by 2.0‐fold, and Gr28a was downregulated by 0.8‐fold and upregulated by 3.6‐fold upon treatment with 0.5 mg/kg and 1 mg/kg azadirachtin in 24 hr. Gr genes participated in the identification of bitterness and we speculated that Gr genes may indirectly lead to the occurrence of antifeeding behavior.

中文翻译：

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印za素对第五龄斜纹夜蛾幼虫的拒食作用及印za素对口器周围目标感官的分析。

弄清第五龄斜纹夜蛾头上的感性的类型，数量和分布（Fabricius）（鳞翅目：夜蛾科）幼虫，并鉴定印ach素作用于幼虫的主要感觉器，使用扫描电子显微镜研究头部和口器上的感觉器的形态。通过微滴法将五龄幼虫头部上的四个感官-基本感官，感性感官，stylosnic styloconicum和感性感线虫-分别以0、0.1、0.5、1、2和4 mg / kg印za素处理。幼虫对印za素具有明显的拒食作用。印za素的浓度越高，其抗喂食活性的现象越明显。stylosoniconicum和Trichodeum senzalum是印za素的主要感受器官。当使用1 mg / kg印za素治疗stystyoniconicum和sensillum basiconicum时，其第五龄幼虫斜纹夜蛾显示出明显的拒食活性，24小时的累积采食量不超过叶面积的30％。定量逆转录聚合酶链反应验证了某些Grs的表达模式，表明Grst43a上调了1.3和3.9倍，Gor24上调了2.5和3.3倍，Gr5a下调了0.6倍和2.0上调倍数，用0.5 mg / kg和1 mg / kg印za素治疗24小时后，Gr28a下调0.8倍，上调3.6倍。Gr基因参与了苦味的鉴定，我们推测Gr 基因可能间接导致反喂食行为的发生。