Efficient mate location is critical for reproductive success in male moth. While plant volatiles can synergize attraction to sex pheromones in many insects, the underlying mechanisms remain poorly understood. We examined this interaction using the cotton bollworm Helicoverpa armigera, a major pest that serves as a model due to its well-defined pheromone system. We found that the plant volatiles (Z)-3-hexenyl acetate and linalool were not attractive alone, yet each significantly enhanced male attraction when combined with the sex pheromone in wind tunnel assays. Single sensillum recording revealed that this synergy occurs peripherally within the pheromone-sensitive type A sensilla. Furthermore, transgenic Drosophila OR expression, and CRISPR-Cas9-mediated HarmPBP1 knockout, demonstrated that the pheromone-binding protein HarmPBP1, but not the odorant receptor HarmOR13, is critical for the synergistic effect of (Z)-3-hexenyl acetate. Our study elucidates a peripheral mechanism for olfactory signal integration, providing insights for developing sustainable behavioral control strategies.

Where to lay eggs is critical for insect females to avoid risks and ensure offspring survival. Females of the oriental armyworm, Mythimna separata, deposit their eggs inside narrow slits to evade predators. However, the sensory mechanism by which they choose the optimal slit for egg laying remains unclear. Here, we demonstrate the requirement of mechanosensation for selecting oviposition slit. Females preferentially deposit eggs in the leaf sheath or in folded paper gaps, thereby shielding their eggs from parasitism by Trichogramma dendrolimi. Specifically, females prefer the opening of 0.5 mm in rigid gaps. Surgical ablation of ovipositor bristles leads to disrupted gap selection and increased parasitism. Mechanosensitive receptor Piezo is found within these bristles and responds to the mechanical deflection of a single bristle. Piezo mutants show random egg laying and vulnerability to parasitoids. Collectively, our findings provide insight into the involvement of mechanosensation in insect egg-laying site choice.

The sweet potato whitefly, Bemisia tabaci (Gennadius) is one of the most devastating pests, inflicting severe damage on a wide range of crops. The tetramic acid insecticides, spirotetramat and spiropidion, act as inhibitors of lipid biosynthesis by targeting acetyl-coenzyme A carboxylase (ACCase), disrupting fatty acid biosynthesis and energy metabolism. In the present study, a total of 47 field populations were collected across China in 2021 and 2022, and their susceptibilities to spirotetramat and spiropidion were determined in the laboratory. The results showed that in contrast to their toxicities against nymphs, spirotetramat and spiropidion exhibited minimal toxicity against B. tabaci adults. B. tabaci nymphs from field populations exhibited susceptibility or low resistance to spirotetramat, with LC50 values ranging from 2.85 to 13.58 mg L- 1 and resistance ratio (RR) from 1.7 to 8.2. There was a variation in the sensitivity of B. tabaci field populations towards spiropidion, with LC50 values ranging from 13.12 to 120.13 mg L- 1 and RR from 3.5 to 23.4. The baseline susceptibility of B. tabaci nymphs to spiropidion was determined to be 24.06 mg L-1, corresponding to the median lethal concentration (LC50) calculated from 43 field populations. Cross-resistance was observed between spirotetramat and spiropidion, as well as between cyantraniliprole and tetramic acid insecticides. However, no significant cross-resistance was found between neonicotinoids and tetramic acid insecticides. Collectively, these findings improve our knowledge on the toxicity of tetramic acid insecticides to B. tabaci populations in China and provide valuable information for their scientific application in the field.

Interactions among insects, plants, and microorganisms are fundamental to ecosystem dynamics, with floral nectar and pollen serving as key resources for various organisms. Yeasts, such as Metschnikowia reukaufii, commonly found in nectar, influence nectarial attraction through volatile compounds (VOCs), yet the underlying biological mechanisms remain elusive. Here, we show that isoamyl alcohol, a prominent yeast VOC, attracts oriental armyworm moths (Mythimna separata) to pollen-rich, yeast-fermented nectar. In a series of electrophysiological and behavioral assays, we show that isoamyl alcohol activates a single class of highly specific olfactory sensory neurons expressing the olfactory receptor MsepOR8. In the moth antennal lobe, these neurons target the AM2 glomerulus, which responds to isoamyl alcohol. Genetic disruption of MsepOR8 leads to complete abolition of both physiological and behavioral responses to isoamyl alcohol, resulting in an impaired ability to locate nectar sources. Moreover, we show that isoamyl alcohol-induced foraging behavior fosters a mutualistic relationship between yeast and moths to some extent, enhancing yeast dispersal and increasing moth reproductive success. Our results unveil a highly specific mechanism by which a yeast-derived VOC facilitates insect-yeast mutualism, providing insights into insect-microbe interactions within pollination ecosystems.

The mechanism of sex pheromone reception in the male cotton bollworm Helicoverpa armigera has been extensively studied because it has become an important model system for understanding insect olfaction. However, the pathways of pheromone processing from the antenna to the primary olfactory center in H. armigera have not yet been clarified. Here, the physiology and morphology of male H. armigera olfactory sensory neurons (OSNs) were studied using single sensillum recording along with anterograde filling and intracellular recording with retrograde filling. OSNs localized in type A sensilla responded to the major pheromone component cis-11-hexadecenal, and the axonal terminals projected to the cumulus (Cu) of the macroglomerular complex (MGC). The OSNs in type B sensilla responded to the behavioral antagonist cis-9-tetradecenal, and the axonal terminals projected to the dorsomedial anterior (DMA) unit of the MGC. In type C sensilla, there were 2 OSNs: one that responded to cis-9-tetradecenal and cis-11-hexadecenol with the axonal terminals projecting to the DMA, and another that responded to the secondary pheromone components cis-9-hexadecenal and cis-9-tetradecenal with the axonal terminals projecting to the dorsomedial posterior (DMP) unit of the MGC. Type A and type B sensilla also housed the secondary OSNs, which were silent neurons with axonal terminals projected to the glomerulus G49 and DMP. Overall, the neural pathways that carry information on attractiveness and aversiveness in response to female pheromone components in H. armigera exhibit distinct projections to the MGC units.

The descending neurons (DNs) of insects connect the brain and thoracic ganglia and play a key role in controlling insect behaviors. Here, a comprehensive investigation of the distribution and organization of the DNs in the brain of Helicoverpa armigera (Hübner) was made by using backfilling from the neck connective combined with immunostaining techniques. The maximum number of DN somata labeled in H. armigera was about 980 in males and 840 in females, indicating a sexual difference in DNs. All somata of DNs in H. armigera were classified into six different clusters, and the cluster of DNd was only found in males. The processes of stained neurons in H. armigera were mainly found in the ventral central brain, including in the posterior slope, ventral lateral protocerebrum, lateral accessory lobe, antennal mechanosensory and motor center, gnathal ganglion and other small periesophageal neuropils. These results indicate that the posterior ventral part of the brain is vital for regulating locomotion in insects. These findings provide a detailed description of DNs in the brain that could contribute to investigations on the neural mechanism of moth behaviors.

The sense of taste plays a crucial role in herbivorous insects by discriminating nutrients from complex plant metabolic compounds. The peripheral coding of taste has been thoroughly studied in many insect species, but the central gustatory pathways are poorly described. In the present study, we characterized single neurons in the gnathal ganglion of Helicoverpa armigera larvae using the intracellular recording/staining technique. We identified different types of neurons, including sensory neurons, interneurons, and motor neurons. The morphologies of these neurons were largely diverse and their arborizations seemingly covered the whole gnathal ganglion. The representation of the single neurons responding to the relevant stimuli of sweet and bitter cues showed no distinct patterns in the gnathal ganglion. We postulate that taste signals may be processed in a manner consistent with the principle of population coding in the gnathal ganglion of H. armigera larvae.

The olfactory system of insects is essential in many crucial behaviors, such as host seeking, mate recognition, and locating oviposition sites. Lepidopteran moths possess two main olfactory organs, including antennae and labial palps. Compared to antennae, the labial palps are relatively specific and worthy of further investigation due to the labial-palp pit organ (LPO), which contains a large number of sensilla located on the tip segment. The fall armyworm, Spodoptera frugiperda , is a worldwide lepidopteran pest, which can damage more than 350 plants and cause significant economic losses. In this study, we surveyed the structure of the labial palps and LPO of S. frugiperda using a super-high magnification lens zoom 3D microscope. Then, the distribution and fine structure of sensilla located in the LPO of S. frugiperda were investigated using scanning electron microscopy. Subsequently, the electrophysiological responses of labial palps to CO 2 and 29 plant volatiles were recorded by using electrolabialpalpography. Our results showed the fine structure of labial palps, the LPO, and the sensilla located in the LPO of S. frugiperda . Moreover, we demonstrated that the labial palps are olfactory organs that respond to both CO 2 and other volatile compounds. Our work established a foundation for further study of the roles of labial palps in insect olfactory related behaviors. Further investigations on the function of labial palps and their biological roles together with CO 2 and volatile compound responses in S. frugiperda are necessary, as they may provide better insect behavioral regulators for controlling this pest.

The pheromone system of heliothine moths is an optimal model for studying principles underlying higher-order olfactory processing. In Helicoverpa armigera, three male-specific glomeruli receive input about three female-produced signals, the primary pheromone component, serving as an attractant, and two minor constituents, serving a dual function, that is, attraction versus inhibition of attraction. From the antennal-lobe glomeruli, the information is conveyed to higher olfactory centers, including the lateral protocerebrum, via three main paths – of which the medial tract is the most prominent. In this study, we traced physiologically identified medial-tract projection neurons from each of the three male-specific glomeruli with the aim of mapping their terminal branches in the lateral protocerebrum. Our data suggest that the neurons’ widespread projections are organized according to behavioral significance, including a spatial separation of signals representing attraction versus inhibition – however, with a unique capacity of switching behavioral consequence based on the amount of the minor components.

棉铃虫Helicoverpa armigera主要借助于性信息素通讯完成雌雄识别,实现交配和种群繁衍.关于棉铃虫感受性信息素机制的研究一直是我国化学生态学领域的热点和重心,研究结果有助于开发和改进棉铃虫防治的性引诱剂.本文将对棉铃虫雄虫感受雌虫释放的性信息素的机制进行综述,以期为深入研究棉铃虫及其他相关昆虫的性信息素感受的分子和神经机理提供参考.棉铃虫雌虫性信息素腺体合成和释放多种长链、饱和或非饱和的脂肪醛和醇等化合物,其中Z11-16:Ald为主要性信息素成分,Z9-16: Ald和Z9-14: Ald为次要性信息素成分,不同组分按一定比例混合可明显增强对雄性棉铃虫的引诱效果,而化合物Z11-16: OH和高剂量的Z9-14: Ald对性信息素引诱活性具有明显的抑制效果.相应地,雄性棉铃虫触角上A,B和C3种类型的毛形感器能够感受这些信息化合物.A类型毛形感器内表达受体OR13感受Z11-16∶Ald,B类型毛形感器内表达OR14b感受Z9-14: Ald,C类型毛形感器内表达OR6和OR16感受Z9-16: Ald,Z9-14: Ald,Z11-16:Ac和Z11-16: OH.受体的表达位置和功能与不同类型毛形感器的电生理反应特性相一致.钙离子成像证明在棉铃虫触角叶内的3个扩大型神经纤维球接受这些气味信息,其中神经纤维球云状体接受Z11-16: Ald,背中间后侧纤维球接受Z9-16: Ald,背中间前侧纤维球接受Z9-14: Ald,Z11-16:Ac和Z11-16: OH.这些研究成果在感器、受体和脑中枢水平上揭示了棉铃虫感受性信息素的机制,在这些研究基础上,我们认为需要深入开展以下方面的研究:(1)进一步鉴定相关性信息素受体的功能和定位;(2)深入研究脑内嗅觉高级中枢对性信息素信息的处理和整合神经机制;(3)明确棉铃虫性信息素感受受到寄主植物、光周期、温度、湿度等环境因素的影响及机制.

[目的]鉴定雄性棉铃虫Helicoverpa armigera成虫触角性信息素感器嗅觉受体神经元的功能、形态及中枢投射路径.[方法]利用单感器记录技术记录棉铃虫嗅觉受体神经元对性信息素的反应,同时采用荧光染料作为示踪剂染色标记嗅觉受体神经元;使用免疫组织化学方法处理相应的脑组织,标记脑内触角叶的神经纤维球结构;用激光扫描共聚焦显微镜获取图像数据,使用图形软件ZEN和Amira 4.1.1进行三维结构重建.[结果]记录到雄性棉铃虫成虫触角上长毛形感器对主要性信息素成分Z11-16:Ald产生明显的电生理反应,并成功染色标记了该感器内的嗅觉受体神经元.染色标记显示该感器内具有两个嗅觉受体神经元,其轴突通过触角神经分别投射触角叶内的云状体神经纤维球和普通神经纤维球.[结论]单感器记录与神经元示踪两技术结合能够用于鉴定昆虫触角嗅觉受体神经元的功能、形态和投射至神经纤维球的路径.与赖氨酸钴方法比较,使用荧光染料法进行神经元示踪,操作更简便,且易于进行三维空间分析,为调查棉铃虫其他嗅觉神经元的投射路径以明确外周气味受体感受与中枢系统的联系提供了有力技术支持.

[目的]揭示绿盲蝽Apolygus lucorum腹神经节的组成结构.[方法]采用免疫组织化学染色方法,利用突触蛋白抗体对绿盲蝽成虫的腹神经节进行免疫标记,激光共聚焦扫描显微镜扫描照相获得原始数据,用图像分析软件进行标记,构建三维结构模型.[结果]绿盲蝽成虫腹神经节位于腹神经索的末端,与其前方的后胸神经节和中胸神经节紧密融合,形成后部神经节.与脑和胸神经节类似,腹神经节由周围的细胞体和内部的神经髓构成.腹神经节的神经纤维束主要包括位于腹侧的两条纵向神经连索和向两侧发出的9束神经纤维.9束神经纤维连接着9个神经原节,即富含突触联系的神经髓.这些神经原节紧密融合,无明显的边界,最后两节形成膨大的末端腹神经节.两侧的神经原节由横向的神经连锁连接起来.腹神经节外周的细胞体数量较多,排列紧密,大小一致,仅在前端背侧中间和后端腹侧中间位置分别有2个和5个体积较大的细胞体.[结论]本研究结果明确了绿盲蝽腹神经节的结构,为进一步研究昆虫的行为调控及神经系统发育和演化奠定一定的形态学基础.

The anatomical organization of distinct regions in the insect brain often reflects their functions. In the present study, the brain structure of Apolygus lucorum was examined by using immunolabeling and three-dimensional reconstruction. The results revealed the location and volume of prominent neuropils, such as the antennal lobes (AL), optic lobes (OL), anterior optic tubercles (AOTU), central body (CB), lateral accessory lobes (LAL), mushroom lobes, and distinct tritocerebral neuropils. As expected, this brain is similar to that of other insects. One exception, however, is that the antennal lobes were found to be the most prominent neuropils. Their size relative to the entire brain is the largest among all insect species studied so far. In contrast, the calyx, a region getting direct input from the antennal lobe, has a smaller size relative to the brain than that of other species. These findings may suggest that olfaction plays an essential role for A. lucorum.