Abstract Understanding the oviposition and foraging behaviour of pestiferous lepidopterans on their economically important food plants guides the development of effective pest management tactics. Here, we examined the oviposition behaviour and larval establishment of three noctuid species on a single crop—capsicum ( Capsicum annuum ). We selected pest species that are known to infest capsicum crops to varying degrees—the cotton bollworm, Helicoverpa armigera ; the cluster caterpillar, Spodoptera litura ; and the fall armyworm, Spodoptera frugiperda . Although related, these species differ in their known host‐plant preferences and larval feeding behaviour. We conducted a series of glasshouse experiments examining moth oviposition and larval survival on different crop stages and the ability of neonate larvae to feed and establish on capsicum fruits at different stages of development. Although all three species oviposited on capsicum plants, S. litura laid more eggs than the other species and targeted most of their eggs to plants rather than the cage wall, indicating a preference for the plant. S. litura larvae demonstrated the highest level of survival (48%) when left unrestricted on capsicum plants, whereas only a small proportion of S. frugiperda (12%) and H. armigera (3%) larvae survived on capsicum plants. Surprisingly, most surviving S. frugiperda larvae were found feeding inside capsicum fruits. The results generated in this study demonstrate how in‐field infestations of these noctuids in capsicum arise and will guide further development of pest management strategies for these pests in capsicum.

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.

Helicoverpa armigera is a typical polyphagous species whose larvae primarily bore in flower buds and fruits of host plants, causing serious damage to many crops. Olfaction plays a key role in host selection, but the molecular basis of olfactory perception in larvae is poorly understood. Herein, we identified a highly expressed odorant receptor, HarmOr54, in larval antennae through qRT-PCR and in situ hybridization experiments. Drosophila T1 neurons expressing HarmOr54 ectopically showed specific responses to (-)-bornyl acetate and 2-ethylhexyl acetate. CRISPR/Cas9-generated homozygous mutant larvae lost avoidance to (-)-bornyl acetate, unlike wild-type larvae, while 2-ethylhexyl acetate showed no behavioral effect. Structural modeling and docking revealed that both ligands bound to the same HarmOr54 pocket, but (-)-bornyl acetate displayed stronger binding affinity. These findings enhance our understanding of the olfactory mechanisms in lepidopteran larvae and provide new insights into pest control strategies targeting the larval stage.

Matrix metalloproteinases (MMPs) play crucial roles in both physiological and pathological conditions by degrading the extracellular matrix; however, the roles and regulatory mechanisms of MMPs in brain development remain insufficiently understood. In this study, using the lepidopteran insect Helicoverpa armigera, the cotton bollworm, a serious agricultural pest, as an experimental model, we revealed that MMP2 is an important factor in insect brain development during metamorphosis under steroid hormone 20-hydroxyecdysone (20E) regulation. MMP2 is highly expressed in the brain during metamorphosis. MMP2 is localized in some surface and internal cells in the brain during metamorphosis. The knockdown of Mmp2 by RNA interference in larvae repressed brain development, accompanied by an increase in autophagy and a decrease in cell proliferation. In addition, the nutrient levels of glucose and glutamate decreased in the brain, and the expression of glucose transporters and glutamate transporters decreased after Mmp2 was knocked down. The transcription of Mmp2 was upregulated by 20E via the transcription factor forkhead box O (FOXO) in a time- and concentration-dependent manner. These data suggest that MMP2 facilitates neural cell proliferation and nutrient supply, and ultimately regulates brain development during insect metamorphosis.

BackgroundMolting is a critical yet vulnerable stage in insect development, during which the peritrophic matrix is temporarily disrupted. This transient loss of gut barrier integrity can allow gut bacteria to escape into the hemocoel, where they may proliferate in the nutrient-rich hemolymph, leading to developmental impairments or septicemia. Despite this threat, insects typically complete molting successfully, suggesting the involvement of robust immune mechanisms that control hemolymph bacterial load.ResultsThis study identifies the Spätzle gene cluster (HaSpz3–6) in the cotton bollworm (Helicoverpa armigera) as essential for limiting hemolymph bacterial proliferation during molting. Knockdown of HaSpz3–6 suppresses antimicrobial peptide expression, leading to Bacillus spp. overgrowth and delayed molting. The ensuing bacterial proliferation triggers tryptophan catabolism, elevating serotonin and N-acetylserotonin (NAS) levels. Serotonin enhances phagocytosis, which cooperates with reactive oxygen species (ROS) to reduce bacterial burden. NAS subsequently mitigates oxidative stress by scavenging excess ROS.ConclusionsThese findings reveal that Spätzle-mediated immunity is crucial for bacterial regulation during molting. When this pathway is impaired, tryptophan catabolism provides a compensatory defense, albeit with developmental trade-offs. Overall, this study underscores the plasticity of insect immune responses and highlights the critical role of Spätzle in safeguarding developmental transitions.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12915-026-02504-y.

The cotton bollworm (Helicoverpa armigera, Lepidoptera: Noctuidae) is a globally distributed agricultural pest. When conducting expression analysis of its functional genes, appropriate reference genes should be selected to ensure the reliability of the results. In this study, five algorithms including Delta Ct, GeNorm, Normfinder, BestKeeper, and RefFinder were used to evaluate the expression stability of eleven candidate reference genes under different developmental stages, larval tissues, adult sexes, plant secondary substance stresses, and insecticide treatments in H. armigera. The candidate genes included Actin, Tubulin, EF-1α, RPS3, RPS15, RPL27, RPL32, 28S, GAPDH, SOD, and TRX. The reliability of the recommended reference gene combinations was validated using the growth arrest and DNA-damage-inducible gene 45 (GADD45). The results showed that normalizing relative expression of the target gene with the combination of the two most stable reference genes is recommended. Specifically, the combination of RPS3 + RPL27 is recommended for developmental stage comparisons; RPL32 + RPL27 for larval tissues; RPS3 + RPL27 for adult sex comparisons; GAPDH + RPL32 under tannic acid stress; RPL32 + RPS3 under quercetin stress; RPS15 + RPL32 under 2-tridecanone stress; RPS3 + RPL32 under ZQ-8 stress; RPL27 + TRX following chlorantraniliprole treatment; and RPL27 + RPL32 following indoxacarb treatment. Moreover, larvae exposed to three concentrations of plant secondary substances and to sublethal doses of insecticides exhibited significant upregulation of GADD45: after 4 h of exposure to 1% tannic acid, 0.1% and 1% quercetin, 1% 2-tridecanone, and 0.05% ZQ-8; after 15 h of chlorantraniliprole treatment; and after 24 h of indoxacarb treatment. Thus, GADD45 was overexpressed in response to various plant secondary substances and insecticide treatments, indicating its involvement in the detoxification and metabolism of H. armigera. This study proves to be helpful for selecting reference genes in H. armigera under plant secondary substance and insecticide stress and lays the foundation for further research utilizing GADD45 as a molecular target for pest control.

Insect vectors are responsible for transmitting the majority of plant viruses. While the interplays between insect vectors and viruses have been extensively investigated, how other organisms associated with the shared host plants of the insect and virus impact virus transmission dynamics, and the corresponding viral countermeasures, remain largely unknown. We explored the modulation of whitefly-mediated transmission of geminiviruses by two non-vector herbivores and the role of viral C2 proteins. The infestation of cotton bollworm induced the accumulation of jasmonic acid (JA) in plants, which in turn elicited plant repellence against whiteflies. Tomato yellow leaf curl virus (TYLCV) and its C2 inhibited JA-induced plant repellence against whiteflies. However, infestation by another non-vector insect, the green peach aphid, induced salicylic acid (SA) accumulation, thereby decreasing TYLCV infection in plants. TYLCV C2 dampens SA-induced antiviral defenses against TYLCV. The functions of TYLCV C2 in subverting both JA-induced plant repellence against the insect vector and SA-induced antiviral defenses seem conserved, as it was also observed in C2 proteins encoded by members of two other genera Becurtovirus and Topocuvirus. Mechanistically, geminiviral C2 proteins did not affect JA or SA biosynthesis but suppressed the signal transduction of both pathways. This study demonstrates that geminiviral C2 proteins suppress JA- and SA-mediated defenses induced by non-vector herbivores, thereby facilitating whitefly-mediated virus transmission. © 2026 Society of Chemical Industry.

The transcription factor E93 modulates Mmp1 expression to regulate testicular fusion during the prepupal stage in Helicoverpa armigera.

The cotton bollworm, Helicoverpa armigera (Hübner), a cosmopolitan agricultural pest, inflicts severe impacts on global agriculture. As a poikilotherm, it was highly susceptible to climate change, yet critical gaps persist in understanding how its sensitivity interacts with climatic shifts-knowledge essential for integrated pest management (IPM). We, therefore, analyzed H. armigera's susceptibility to temperature variations using long-term pest population and meteorological data from Maigaiti and Bachu Counties (southern Xinjiang) and Shawan County (northern Xinjiang). The results showed H. armigera populations increased overall, with reduced interannual fluctuation magnitude. The main meteorological factors influencing the interannual population changes of H. armigera in Maigaiti, Bachu, and Shawan were Tmax difference in winter (98.0%), Tmin difference in May (80.7%), and Tmin difference in July (99.4%), respectively. Higher winter temperature (particularly February) reduced the spring population sizes across all three regions, with only the population in Bachu showing a significant correlation. For annual populations, warmer winter caused a significant decline in Bachu, a marked increase in Maigaiti, and a non-significant rise in Shawan. Summer temperature below 33 °C boosted populations in all regions; above 33 °C, the Maigaiti population declined non-significantly, while the Bachu population dropped significantly. Climate warming advanced the pest's first appearance, delayed its disappearance, and extended its active period, increasing population size-a trend projected to intensify in the future. Maigaiti and Shawan populations were governed by Tmax in winter and Tmin in July, respectively, whereas the Bachu population was constrained by temperature differences during multiple key growth and development periods throughout the year. These divergent regulatory patterns and climatic responses reflect varying vulnerability levels, providing a theoretical basis for targeted H. armigera control.

BackgroundCotton is an important crop that provides a natural fiber source for the textile industry. Polyphenol oxidase (PPO) is a type of ubiquitous metalloproteinase in plants, which play crucial roles in regulating plant growth and development, as well as plant resistance against biotic and abiotic stresses. Although the whole genome sequence of Gossypium hirsutum L. (G. hirsutum) has long been published, this gene family has not yet been well studied in cotton.ResultsIn the present paper, we have identified the 51 PPO genes in cotton, and deeply analyzed 15 PPO genes in G. hirsutum, which are named GhPPOs. We found that three conserved domains - tyrosinase, DWL, and KFDV, were present in all 15 GhPPOs. We also analyzed the molecular characterization, phylogenetic relationships, gene structure, chromosome locations, 3D structure, and expression profiles of all the PPO genes identified. Based on the phylogenetic analysis, these PPO genes were classified into five groups (I, II, III, IV and V). The 15 GhPPO genes are distributed across eight chromosomes, and gene structure analysis showed that nine GhPPOs are devoid of introns. Analysis of cis-acting elements in GhPPOs promoters indicated their potential fundamental roles in response to plant growth, development, and stresses. Transcript profiling and RT-qPCR analysis revealed that GhPPO3/11 showed high expression levels during cotton fibre elongation, and GhPPO3/5 can be induced in response to cotton bollworm infestation. Moreover, the 3-dimensional structures of GhPPO3/ 11 and GhPPO3/ 5 were predicted by homolog modeling, and we found that all of them possess similarity spatial structures, with two independent domains, which could be the structural basis for performing biological functions.ConclusionsThese findings not only provide valuable insights into the phylogenetic relationships, gene structure, cis-acting elements, and functional characteristics of upland cotton PPOs, but also shed light on their potential roles in cotton fibre elongation and response to biotic stresses.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12864-025-11906-1.

Gene editing technologies are playing an increasingly important role in the study of insect gene functions. Appropriate incubation humidity helps improve the hatching rate of insect eggs. However, to date, no study has evaluated the impact of humidity on the hatching rate of gene-edited eggs or the subsequent development of the larvae. Using the cotton bollworm Helicoverpa armigera (Lepidoptera: Noctuidae) as a model, we investigated the weight and hatching rate of microinjected eggs under different humidity conditions. We determined the larval development time and pupal weight and calculated the larval gene editing efficiency. The results showed that post-microinjection incubation under high humidity (RH = 95%) had a significant influence on CRISPR/Cas9 gene-edited eggs. The key research results indicate that, compared with the incubation environment with RH ≤ 80%, after 48 h of incubation under 95% RH, the hatching rate of H. armigera eggs increased by more than 27.5%, with higher egg saturation and greater egg weight; meanwhile, the larval developmental duration was shorter and the pupal weight was also greater. These results establish a humidity-regulated developmental recovery protocol for gene-edited insects, which provides theoretical and practical support for optimizing post-microinjection recovery processes in gene-edited insects.

The cotton bollworm (Helicoverpa armigera) is a major agricultural pest in the world, belonging to the family Noctuidae within the order Lepidoptera, and undergoes diapause in the pupal stage. During the pupal stage, HaDH acts on the prothoracic gland to stimulate the synthesis of ecdysteroids, playing a crucial role in diapause termination. The functional activation of DH requires binding to its receptor, the diapause hormone receptor (DHR), and the tissue-specific expression of DHR varies across insect species. The regulatory mechanism of HaDH during H. armigera development remains to be elucidated. This study focuses on the spatio-temporal expression analysis of diapause hormone (HaDH) and diapause hormone receptor (HaDHR) in H. armigera, covering their expression patterns in the egg, larval, pupal and adult stages.The expression trends of HaDH and HaDHR were generally consistent. HaDH was expressed throughout the entire life cycle of H. armigera, with expression mainly localized to the head; its expression levels followed the pattern: lowest in eggs, low in larvae, highest in pupae, and high in adults. HaDHR was also expressed throughout the life cycle (from egg to adult); its overall expression trend was consistent with that of HaDH: lowest in eggs, low in larvae, high in pupae, and highest in adults. The continuous expression of both molecules throughout the H. armigera life cycle indicates that HaDH is likely involved in regulating basic metabolic processes essential for insect development. The spatio-temporal expression characteristics and potential regulatory functions of HaDH and HaDHR revealed in this study provide an important basis for further elucidating the physiological roles for HaDHR in growth and development. Collectively, these studies illustrate that HaDHR not only universally participates in insect diapause regulation but also extends its functional roles to multiple developmental stages, including embryonic development, larval growth, development of pupae and moth.

HSF-1 regulates FoxO expression to induce diapause in the cotton bollworm, Helicoverpa armigera via upstream HIF-1α and MNK signaling.

Abstract Dead-end trap cropping is a particular case of trap cropping involving trap crop plants on which targeted insect pests cannot survive. Dead-end trap crops can function as a sink for pests, preventing their movement from the trap crop to the main crop, thus greatly reducing reliance on pesticide applications. Wintercress Barbarea vulgaris Aiton (Brassicaceae) and vetiver grass Chrysopogon zizanioides (L.) Roberty (Poaceae) are among the plant species most-studied as dead-end trap crops for diamondback moth Plutella xylostella L. (Lepidoptera: Plutellidae) and the stemborers Chilo partellus Swinhoe (Lepidoptera: Crambidae) and S. inferens Walker (Lepidoptera: Noctuidae), respectively. Additional dead-end crops target important pests like cotton bollworm, corn earworm, green peach aphid, western tarnished plant bug, root-knot and root-lesion nematodes, silverleaf whitefly, and different species of fruit flies and thrips. Besides the inherent characteristics of a plant species that make it naturally function as a dead-end trap crop, such as the presence of particular plant secondary metabolites, other types of dead-end trap crops involve the use of transgenesis and the use of biological control agents. This article reviews the topic of dead-end trap cropping, providing also an explanation of some of the mechanisms involved and the factors that affect the successful implementation of this type of trap cropping.

Tobacco (Nicotiana tabacum), an allotetraploid species extensively cultivated worldwide, serves as a key model system for plant research but exhibits high susceptibility to insect pests. The comprehensive molecular mechanisms underlying N. tabacum’s response to insect pests remain poorly characterized. In this study, we collected leaf RNA-seq samples from tobacco plants at 0, 6, and 24 h after exposing them to either the aphid (Myzus persicae) or the cotton bollworm (Helicoverpa armigera). The numbers of differentially expressed genes (DEGs) responding to cotton bollworms exceeded those responding to aphids at both 6 and 24 h. Pathway enrichment analysis, weighted gene co-expression network analysis (WGCNA), and clustered expression pattern analysis revealed that the most significantly enriched pathways were involved in hormone signal transduction, secondary metabolism, and the regulation of transcription factors. We employed CRISPR/Cas9 technology to disrupt Jasmonoyl-L-isoleucine hydrolase 1 (JIH1), which was significantly upregulated following insect treatment as confirmed by both RNA-seq and qRT-PCR analyses, to validate its role in insect resistance. The weight of cotton bollworms decreased by 25.67% when feeding on ntjih1-1 plants compared to wild-type (WT) plants. In ntjih1-1 plants, transcripts involved in jasmonic acid (JA), salicylic acid (SA), and ethylene (ET) signaling pathways were activated. Concurrently, plant height decreased, whereas primary root length increased. Interestingly, the expression levels of 13 of 15 JAZ genes were repressed in ntjih1-1 plants. The ntjih1-2 plants showed no enhanced resistance to cotton bollworms, potentially due to functional selective evolution of NtJIH1-1 and NtJIH1-2 during tobacco chromosome doubling. Our results indicate that JIH1 may play a vital role in balancing growth and defense in the plant’s immune response to herbivory.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12870-025-07801-2.

The majority of pheromone receptors (PRs) in the cotton bollworm Helicoverpa armigera have been deorphanized, but the function of HarmOR11, a PR highly expressed in both male and female antennae, has remained controversial. We expressed HarmOR11 in Drosophila T1 neurons and found that the neurons respond to plant volatiles benzyl acetate, methyl phenylacetate, and methyl benzoate. When we knocked out HarmOR11 by CRISPR-Cas9, the type A sensilla on the male antennae lost responsiveness to all the three compounds and the enhancing effect of the three compounds on behavioral responses of males toward the sex pheromone disappeared; the trichoid sensilla on female antennae responsive to all the three compounds, originally accounting for 15.38% on wild-type antennae, were no longer responsive, and female preference for oviposition in proximity to these compounds significantly decreased. The discovery advances understanding of PR function evolution and provides new opportunities for enhancing the attractiveness of pheromone traps.

Pink bollworm (Pectinophora gossypiella) is a major pest of cotton worldwide, including in Pakistan, causing substantial quantitative and qualitative yield losses. Therefore, the effectiveness of the egg parasitoid Trichogramma chilonis was evaluated for the management of pink bollworm in cotton. The field experiment was conducted during the cotton growing season at the experimental fields of the Nuclear Institute of Agriculture, Tandojam. Two experimental plots were sown with the cotton variety NIA-Noori. In one plot, T. chilonis was released at a density of two cards per 1/4 acre, while the other plot served as an untreated control without parasitoid release. The results indicated a significant reduction in pink bollworm infestation on cotton flowers and bolls in the T. chilonis-released plot compared to the control. The highest infestation was observed in the control treatment, with 10.67% infestation on flowers and 18.91% on bolls. In contrast, infestation on cotton buds remained nearly the same (1.18%) in both treatments. Based on these findings, it can be concluded that T. chilonis is an effective biological control agent against pink bollworm. Its periodic release is recommended as an eco-friendly and sustainable strategy for managing pink bollworm infestations in cotton.

Characterizing the genetic diversity and population structure can determine whether there is gene flow of the natural population of Helicoverpa armigera (Hübner) under disparate climate and habitat conditions in Northwest China. In this paper, H. armigera was genotyped in various regions of Xinjiang using Genotyping-by-Sequencing (GBS). The samples were compared using the single nucleotide polymorphism (SNP) and insertion deletion (InDel) marker data. The SNPs were used to analyze the population structure and five subgroups were obtained, which was further confirmed by principal component analysis (PCA). The phylogenetic tree identified five cluster populations of H. armigera. The average values of polymorphic information content (PIC) and genetic differentiation index (Fst) are 0.1783 and 0.1293, respectively, which are at a high level. The phylogenetic tree differentiation also indicates that the genetic diversity of cotton bollworm populations in different regions of Xinjiang is low diversity, moderate differentiation, and widespread gene flow. According to correlation analysis of the source of feeding on host plants (Bt cotton and non Bt crops) of H. armigera, seven SNPs with significant differences were obtained. The most significant SNP sequence was compared with the whole genome of H. armigera, and 10 candidate genes were screened. Whether the candidate genes function are related to Bt resistance needs further verification. This study can provide scientific basis for screening Bt resistance genes and formulating refuge strategy of H. armigera in Northwest China.

Cottonseed meal (CSM), an important protein-rich feed ingredient, faces limited utilization in livestock diets due to the presence of free gossypol (FG)—a potent antinutritional toxin. This study aimed to isolate FG-degrading bacteria from the cotton bollworm, Helicoverpa armigera, and to evaluate their potential as probiotics in vitro. Eleven gossypol-tolerant strains were isolated from the gut of Helicoverpa armigera larvae using a screening medium containing gossypol as the sole carbon source. Among these, four lactic acid bacteria strains—Pediococcus acidilactici GM-NP, Pediococcus acidilactici GM-P, Enterococcus faecalis GM-6, and Weissella confusa GM-2—were selected for further investigation of their gossypol degradation capacity and probiotic potential. Probiotic characterization revealed that all strains exhibited tolerance to gastrointestinal fluids and bile salts, safe γ-hemolysis, and strong auto-aggregation, cell surface hydrophobicity, and antimicrobial activity. Solid-state fermentation of CSM with these strains reduced FG content by more than 50%, increased crude protein by over 6%, and elevated acid-soluble protein content by more than 70%, thereby effectively enhancing the nutritional quality of CSM. This study is the first to demonstrate that bacterial isolates from the gut of Helicoverpa armigera possess concurrent high-efficiency gossypol degradation and probiotic properties, providing a theoretical foundation for developing novel probiotic resources and promoting the safe utilization of CSM.

Genetic engineering is the technique of altering an organism’s genetic composition through the introduction of desired genes, often referred to as recombinant DNA technology or gene manipulation. In agriculture, this technology has been applied to develop transgenic plants with insect and herbicide resistance, tolerance to biotic and abiotic stress, and enhanced nutritional profiles. Genetically modified (GM) crops such as Bt cotton and Bt maize have significantly reduced pest infestations, lowered pesticide usage by up to 50%, and increased yields by 20–30% in several regions. Similarly, RNA interference (RNAi) based pest control has been successfully employed against major crop pests such as the corn rootworm and cotton bollworm, offering species-specific and environmentally safer alternatives to chemical pesticides. Genome editing tools, particularly CRISPR/Cas9, are being harnessed to engineer durable resistance against viruses, fungi, and insect pests in staple crops like rice, wheat, and tomato. These approaches not only reduce dependence on chemical pesticides but also contribute to sustainable agriculture by lowering production costs and minimizing environmental impacts. With continuous innovations in genetic pest control, the scope of crop protection and yield enhancement is expanding, demonstrating the transformative role of genetic engineering in modern agriculture.