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Simple Summary: Aphis gossypii Glover (Hemiptera, Aphidoidae) is a worldwide pest. The life history of A. gossypii is complex and there are at least two reproductive strategies in China: holocyclic and anholocyclic types. At present, the strategies of anholocyclic A. gosspii for coping with photoperiod and temperature conditions in autumn and winter remain unknown. Therefore, we studied the reproduction pattern of anholocyclic A. gossypii under different light conditions at low temperatures and performed a transcriptional analysis of them. In this study, the results showed that changes in photoperiod affect the reproduction of A. gossypii. High-throughput sequencing analysis revealed that photoperiodic changes lead to differentially expressed genes (DEGs) in corresponding pathways. Through screening, we found that these DEGs were concentrated in Hsp70 family genes, legumain-like genes, and cathepsin B-like genes. This suggested that these DEGs play an important role in photoperiod changes that regulate the reproduction of A. gossypii. Our results will provide insights into control populations of A. gossypii through the regulation of reproduction. Aphis gossypii Glover (Hemiptera, Aphidoidae) is a polyphagous pest, whose complex phenotypic form, combined with its high fecundity and short reproductive cycle, has caused serious economic losses to agriculture worldwide. Photoperiod plays an important role in the reproduction of aphids. However, the molecular mechanisms underlying its response to seasonal photoperiodic changes are not known. In this study, the effects of different photoperiod treatments (8 L:16 D, 10 L:14 D, 12 L:12 D and 14 L:10 D) on A. gossypii reproduction in the first, third, and fifth generations at low temperatures were investigated. Then, transcriptome sequencing analysis was performed after the fifth generation of A. gossypii, exposed to different photoperiods (8 L:16 D and 12 L:12 D), using high-throughput sequencing technology. The results showed that (I) the effect of photoperiod on aphids was gradually evident with increasing exposure generations. In general, daylight extension help the A. gossypii to reproduce with the optimum photoperiod of L:D 12:12. (II) The transcriptome analysis results showed that 170 differentially expressed genes (DEGs) (123 downregulated and 47 upregulated genes) were identified between aphids under 8 h daylight and 12 h daylight. (III) Gene Ontology (GO) enrichment analysis showed that the DEGs involved in "proteolysis", "metabolic process", "peptidase activity" and "structural molecule activity" were significantly enriched; Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that there were more DEGs in "Longevity regulating pathway-multiple species", "Lysosome", "Endocytosis", "Spliceosome" and "Protein processing in endoplasmic reticulum". (IV) Ten related genes were chosen for validation of statistical analysis based on RNA-Seq by the reverse transcription quantitative (RT-qPCR). The comparison was consistent with the expression pattern and supported the accuracy and reliability of RNA-Seq. In summary, the genes involved in these pathways play an important role in the reproduction of A. gossypii under photoperiodical changes. These will contribute to the sustainable management of cotton aphids through the disruption of their reproduction by the method of RNA interference in the future. [ABSTRACT FROM AUTHOR]

Simple Summary: Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) was first observed in tobacco in Greece in 1889. In China, since the introduction of Euphorbia pulcherrima (Euphorbiales: Euphorbiaceae, native to Central America) at the end of the previous century, B. tabaci has gradually become an increasingly significant agricultural pest. In recent years, the push–pull strategy has been widely applied to the control of the pest. The distinct volatiles are emitted of plants directly affect the efficiency of pushing and pulling; hence, we aimed to study the behavioral responses of B. tabaci to three plants (Gossypium hirsutum, Abutilon theophrasti, and Ricinus communis) during various growth phases (pre-flowering, fluorescence, and fruiting) and analyzed the quality and quantity of volatiles from of three growth stage, as well as identified few compounds that attract or repel the B. tabaci. The results demonstrated that the distinct volatiles are emitted by pre-flowering, flowering, and fruiting plants with varying effects on B. tabaci preference. Three volatile compounds (linalool, (Z)-3-hexenyl acetate, and nonanal) analyzed in this study had trapping/repellent effects on B. tabaci. Therefore, these compounds can be adopted as potential attractants or repellents to control B. tabaci. Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) is a worldwide pest that damages over 900 host plant species. The volatile organic compounds (volatiles) of contrasting plants, as well as their growth stage, influence this pest's infestation behavior. The chemical contents of volatiles isolated from three plants (Gossypium hirsutum, Abutilon theophrasti, and Ricinus communis) during various growth phases (pre-flowering, fluorescence, and fruiting) were examined, as well as their influence on the behavior of adult B. tabaci. The olfactometer studies demonstrated that growth periods of the three plants affected the preference of B. tabaci. Volatiles of piemarker and cotton plants had dissimilar levels of attraction to adults during all stages. Volatile substances released by the castor at the stage of flowering had repellent effect on B. tabaci. In the plant versus plant combination, piemarker volatiles before and during anthesis were most preferred by adults, followed by cotton and then castor. A total of 24, 24, and 20 compounds were detected from volatiles of piemarker, cotton, and castor, respectively, and proportions among the compounds changed during different stages of plant development. The olfactory responses of B. tabaci to volatile compounds presented that linalool and high concentration of (Z)-3-hexenyl acetate had a strong trapping effect on this pest, while nonanal had a significant repellent effect at high concentration. This study indicates that distinct plants and their growth stage affect their attractiveness or repellency to B.tabaci adults, which are mediated by changing plant volatiles. These compounds obtained by analysis screening can be adopted as potential attractants or repellents to control Mediterranean (MED) B. tabaci. [ABSTRACT FROM AUTHOR]

Simple Summary: To elucidate the cotton plant's defense mechanism against Apolygus lucorum, the transcriptomic and metabolomic differences in cotton plants after infestation with A. lucorum were investigated. The results showed that A. lucorum feeding elicits a rapid and strong defense response involved in many primary and secondary metabolic processes during the whole infestation process. The jasmonic acid pathway was shown to mediate the defense mechanisms in cotton plants, and the salicylic acid pathway was attenuated after damage from A. lucorum. The accumulation of condensed tannins was also promoted in cotton plants as a defense mechanism against A. lucorum. These results provided comprehensive insights into the defense system and will help us to discover unknown defensive genes and improve the integrated pest management of A. lucorum. With the wide-scale adoption of transgenic Bacillus thuringiensis (Bt) cotton, Apolygus lucorum (Meyer-Dür) has become the most serious pest and has caused extensive yield loss in cotton production. However, little is known about the defense responses of cotton at the seedling stage to A. lucorum feeding. In this study, to elucidate the cotton defense mechanism, cotton leaves were damaged by A. lucorum for 0, 4, 12 and 24 h. The transcriptomic results showed that A. lucorum feeding elicits a rapid and strong defense response in gene expression during the whole infestation process in cotton plants. Further analysis revealed that at each assessment time, more differentially expressed genes were up-regulated than down-regulated. The integrated analysis of transcriptomic and metabolic data showed that most of the genes involved in jasmonic acid (JA) biosynthesis were initially up-regulated, and this trend continued during an infestation. Meanwhile, the content levels of JA and its intermediate products were also significantly increased throughout the whole infestation process. The similar trend was displayed in condensed tannins biosynthesis. This research proved that, after plants are damaged by A. lucorum, the JA pathway mediates the defense mechanisms in cotton plants by promoting the accumulation of condensed tannins as a defense mechanism against A. lucorum. These results will help us to discover unknown defensive genes and improve the integrated pest management of A. lucorum. [ABSTRACT FROM AUTHOR]

Simple Summary: Since the widespread adoption of Bt cotton in the late 1990s, the green mirid bug, Apolygus lucorum (Hemiptera: Miridae), has become one of the most important pests in cotton fields and some other crops. To manage this destructive pest, Peristenus spretus (Hymenoptera: Braconidae) has been tested in augmentative biological control. In this study, after cotton plants were damaged by different densities of A. lucorum, the behavioral responses of A. lucorum and P. spretus to cotton plants volatiles were evaluated, and the quality and quantity of volatiles from cotton plants were analyzed. The results demonstrated that HIPVs emitted by plants in response to A. lucorum could be influenced by the pest density and could be identified by P. spretus as a signal of the host. Our results would help understand how P. spretus plays a role in biological control against A. lucorum. Plants would release herbivore-induced plant volatiles (HIPVs) to repel herbivores and attract natural enemies after being damaged by herbivores. In this study, after cotton plants were damaged by different densities of Apolygus lucorum, the behavioral responses of A. lucorum and Peristenus spretus to cotton plants volatiles were evaluated, and the quality and quantity of volatiles from cotton plants were analyzed. Only when cotton plants were damaged by four bugs did both A. lucorum and P. spretus show an obvious response to damaged cotton plants, which indicates that cotton defense is correlated with pest density. The collection and analysis of volatiles reveals that the increase in pest density results in the emission of new compounds and an increase in the total number of volatiles with an alteration in proportions among the compounds in the blend. These changes in volatile profiles might provide wasps and mirids with specific information on host habitat quality and thus could explain the behavioral responses of parasitoids and pests. [ABSTRACT FROM AUTHOR]