Shuai Zhang

BACKGROUND: Aphis gossypii shows strong intraspecific host specialization, making it an excellent model for olfaction‐driven host adaptation. Hap1 (cotton‐specialized haplotype) and Hap3 (cucurbit‐specialized haplotype) are the two main haplotypes. Odorant‐binding proteins (OBPs) play pivotal roles in insect host recognition and are potential RNAi targets. This study aims to elucidate the functional role of AgosOBP3 in host specialization of A. gossypii . RESULTS: We used genome‐wide identification, transcriptomic comparison, RNA interference, host choice assays and life table analysis to characterize AgosOBP3 function. We identified 13 OBP genes from the A. gossypii genome, among which AgosOBP3 expression in polyphagous Hap4 was significantly higher than in the cotton‐specialized Hap1 (1.79‐fold, P < 0.05). Life table assays confirmed that Hap1 performed well on cotton but exhibited extremely low survival and reproduction on cucumber, demonstrating typical host‐specialization characteristics. RNAi‐mediated silencing of AgosOBP3 (46.8% expression reduction) substantially altered host preference in Hap1: at 48 h, 70% of control aphids selected cotton, whereas 65% of treated aphids chose cucumber, representing a significant reversal in host selection. Bioassay results revealed that RNAi‐treated Hap1 A. gossypii showed a 39.6% increase in fecundity on cucumber but a 39.5% decrease on cotton. CONCLUSION: The expression level of AgosOBP3 directly governs host preference in A. gossypii toward its specialized hosts. Interference with this gene disrupts host selection preference, redirecting the cotton‐specialized haplotype toward nonadapted hosts. Our results establish AgosOBP3 as a critical determinant of host specialization, offering theoretical insights and a viable molecular target for olfactory disruption‐based sustainable management strategies against aphid pests. © 2026 Society of Chemical Industry.

Background: Cavariella salicicola (Hemiptera: Aphidinae) is a pest on Salix spp. and various Umbelliferae (Apiaceae) vegetables. However, the taxonomic status and phylogenetic relationship of the genus Cavariella within Aphidinae remain controversial due to the small body size and easily confused external morphology. Methods: The complete mitochondrial genome of C. salicicola collected from Oenanthe javanica was sequenced using the Illumina platform and compared with C. theobaldi. The codon usage bias of two Cavariella aphids was assessed through Enc plot, PR2 plot, and neutrality plot analyses. Furthermore, phylogenetic trees were constructed based on both Maximum Likelihood and Bayesian Inference analysis. Results: The C. salicicola mitochondrial genome comprises 15,720 bp and represents a typical circular DNA molecule with a high AT content of 83.8%. It contains the standard 37 genes, including 2 ribosomal RNAs (rRNAs), 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs), and 2 long non-coding regions (control and repeat regions). Varying degrees of codon usage bias were found across different PCGs, and the bias was predominantly influenced by natural selection rather than mutational pressure. The ratio of nonsynonymous to synonymous substitutions (Ka/Ks) indicated that all PCGs in C. salicicola, as well as most other Aphidinae species, are under strong purifying selection. The phylogenetic analysis based on Maximum Likelihood and Bayesian Inference both strongly supported the monophyly of Aphidinae, Macrosiphini, and Aphidini. Crucially, the monophyletic genus Cavariella was resolved as a sister group to all other sampled species within the tribe Macrosiphini. Conclusions: This study provides new molecular data to support the sister relationship of the genus Cavariella to other Macrosiphini aphids. This study will enhance our understanding of phylogenetic relationships within the subfamily Aphidinae.

Aphis gossypii Glover (Hemiptera: Aphididae) is a significant agricultural pest, and the growing issue of pesticide resistance, in this species, has underscored the urgent need to identify alternative, sustainable insecticides. Allium sativum Linnaeus (Asparagales: Amaryllidaceae) is renowned for its broad-spectrum biological activities, including antibacterial and detoxifying properties. Consequently, it has gained considerable attention in the field of plant protection. This study investigates the repellent effects of allicin on A. gossypii and its impact on the pest’s growth and development under fumigation conditions, leveraging the volatile nature of allicin. The findings revealed that fumigation with allicin, diluted 50-fold, exhibited the most pronounced repellent effect on A. gossypii. The repellency rates reached 88% and 86% after 12 and 24 hours of treatment, respectively, while the mortality rates were 46% and 66% for the exact durations. Additionally, allicin significantly influenced the behavioral choices, growth and development, reproductive capacity, and population establishment of A. gossypii. The efficacy of allicin against A. gossypii demonstrated a concentration-dependent effect, with its fumigation activity diminishing as the concentration decreased. These results provide a scientific foundation for the application of allicin in controlling A. gossypii, offer valuable insights for further field trials, and establish a groundwork for utilizing allicin as a fumigant to manage and prevent aphid infestations in agricultural settings.

Aphids are demonstrated to be voracious phloem feeders, among the most damaging insect pests, due to their capacity to decrease crop production and vector plant viruses. Plant secondary metabolites (PSMs) comprise an essential element of plant protection, which in most cases deters and affects aphid performance. Nonetheless, aphids have developed various resistance mechanisms to counteract these chemicals. This review provides an extensive overview of the biological and molecular adaptations that aphids employ to counteract PSMs, including enzymatic detoxification, antioxidant defense, sequestration, behavioral response shifts, suppression of plant defense mechanisms by symbionts, and manipulation of host signaling pathways by effector proteins. We also described the suppression of the defense pathways by aphid-associated viruses, which further complicates plant–aphid interactions. Although significant insights have been gained about each of the individual mechanisms, research gaps remain, particularly in the functional confirmation of detox genes, the communication interactions of the symbionts, and whether sequestration could play an ecological role across species. Intensive efforts involving molecular-based breeding of horticultural crops, as well as traditional breeding with wild relatives highly endowed with aphid-resistant PSM traits, should be employed in the future to provide sustainable crop protection. New technologies in crop genomics, the identification of effectors, and microbiome research promise the development of resistant cultivars that are not only resistant to aphids but also prevent the spread of disease by their vectors. Together, all this knowledge has the potential to produce high-yielding crops that are resistant to aphids and to implement sustainable farming practices.

BACKGROUND: As a polyphagous agricultural pest of global significance, Aphis gossypii exhibits substantial population differentiation and inflicts damage across a broad host range, including economically important leguminous crops. This study aimed to clarify the adaptation of three A. gossypii haplotypes (Hap1, Hap3, Hap4) to four legume hosts: cowpea ( Vigna unguiculata ) varieties Zhongshouluchangfeng (ZLC) and Zhongshoucuichangfeng (ZCC), hyacinth bean ( Lablab purpureus ) and winged bean ( Psophocarpus tetragonolobus ). RESULTS: Results showed Hap1 and Hap4 on cowpeas had higher net reproductive rate ( R ₀ > 25) and intrinsic rate of increase ( r > 0.36) than on hyacinth bean and winged bean ( R ₀ < 6, r < 0.27). Meanwhile, Hap3 exhibited poor life‐table parameters on all legumes. Among legumes, all haplotypes preferred hyacinth bean and refused to feed on winged bean. EPG analysis showed that Hap1 and Hap4 had longer nonprobing time on winged bean, and prolonged xylem ingestion on hyacinth bean. All haplotypes fed longer on cowpea phloem than on hyacinth bean and winged bean. Notably, the proportion of saliva secretion time in the phloem feeding duration of A. gossypii feeding on winged bean exceeded 75%. A. gossypii that fed on cowpeas secreted the highest amount of honeydew CONCLUSION: Different haplotypes of cotton aphids show differentiated adaptability to legumes, and there also is differentiation in the aphid resistance among legumes. These findings can be applied to the formulation of aphid control technologies for legumes and lay a foundation for studying the co‐evolution between A. gossypii and their hosts. © 2025 Society of Chemical Industry.

The cotton-melon aphid (Aphis gossypii) is a globally distributed species with highly differentiated populations and various life cycle types. Based on the haplotype classification of the A. gossypii, this study aimed to quantify the effects of latitude, host specialization on transformation of the sexual morph of the A. gossypii. Additionally, symbiotic bacteria potentially involved in the formation of sexual morph were investigated. The results showed that I):The most frequent haplotypes on the 29 host plants were Hap1 (60.42%), Hap17 (13.29%), and Hap4 (7.55%). Haplotypes in cotton fields of 10 geographic populations were predominantly Hap1 and Hap4. II):A. gossypii from the Northwestern inland, the Yellow River basin, and the Yangtze River basin cotton regions all were induced sexual morphs, except for Hap1 from low latitudes. There are also differences in the efficiency of sex aphid induction between haplotypes under the same region/latitude(Jiangsu Yangzhou), which can be corresponded to three life cycle types: holocyclic (Hap1 and Hap4), facultative (Hap17 and Hap1-1), and specialized parthenogenetic (Hap3 and Hap16) life cycle. Interestingly, sexual morphogenesis of A. gossypii with facultative life cycle are more susceptible influenced by the host. Subsequent field surveys in Yangzhou, Jiangsu have also confirmed that the haplotypes capable of sexual morphology transformation under natural rhythm variations are Hap1 and Hap4. It is worth mentioning that these sexual aphids are mainly distributed on some Malvaceae plants, Chinese prickly ash, and pomegranate. However, aphids with specialized parthenogenetic life cycle can complete their entire life history by overwintering on crops or weeds (such as capsella and veronica) in greenhouses or outdoors. III):The relative abundance of Arsenophonus, Pantoea and Enterobacter varied among haplotypes. In particular. the relative abundance of Arsenophonus was generally higher in holocyclic aphids than in anholocyclic aphids in the parthenogenetic morphology. Additionally, Arsenophonus higher in gynoparas and females than in males in the sexual morphology. It can be observed that the aforementioned symbiotic bacteria may play a role in the development of the specialized or reproductive mode of the A. gossypii. The present study contributes to our understanding of the ecological adaptations of the A. gossypii to different climatic conditions and host plants. Moreover, it will furnish a crucial foundation for unravelling the diversification of reproductive modes exhibited by A. gossypii.