Search Results (62)

The Soybean aphid (Aphis glycines) is a destructive pest that threatens soybeans. In order to develop green and effective control strategies, we propose an EQPAL epidemic model that integrates four developmental stages (1st–2nd stage nymphs, 3rd stage nymphs, 4th stage nymphs, and adults) and a ladybug (Harmonia axyridis) compartment. This model achieves green pest control by artificially releasing a natural enemy of soybean aphids to prey on adult soybean aphids. We analyzed the dynamic behavior of the model and derived the basic reproduction number ${\mathcal{R}}_0$. Using field monitoring data from Changchun City, Jilin Province, China in 2025, the segmented nonlinear least squares method was used for parameter estimation and fitting, resulting in an overall determination coefficient of $R^2=0.8204$. The numerical simulation results showed that the release of ladybugs significantly reduced the density and peak value of soybean aphid adults, and the predation rate $\beta$, predation conversion rate c, and ladybug migration rate $\omega$ were identified as key regulatory parameters. In addition, a cost–benefit analysis was conducted to determine the most cost-effective control measures. Full article

The rice–wheat rotation is a predominant cropping pattern in China, frequently challenged by pests such as aphids in wheat, and Chilo suppressalis and Cnaphalocrocis medinalis in rice. This study investigates the potential of two common landscape plants, Photinia × fraseri and Pittosporum tobira, as functional plants for conserving natural enemies across crop cycles. Arthropod communities were systematically monitored using Malaise traps during the wheat, wheat–rice transition, and rice seasons from 2023 to 2024. Results revealed that both species successfully conserved a diverse natural enemy community, though their structural differentiation was strongly driven by seasonal variation, as confirmed by Heatmap and principal component analysis (PCA) (P. × fraseri: PC1 = 46.3%, PC2 = 23%; P. tobira: PC1 = 40.2%, PC2 = 25%). During the wheat season, both plants synergistically supported rich functional guilds, including predatory guilds (e.g., Episyrphus balteatus, Gnathonarium dentatum, and Harmonia axyridis) and parasitic guilds (e.g., Microplitis tuberculifer and Cotesia spp.). Notably, during the critical wheat-to-rice transition, these shrubs functioned as “habitat anchors,” where P. × fraseri demonstrated superior retention capacity for functional groups like Aphidius gifuensis, mitigating post-harvest habitat fragmentation. During the rice season, distinct functional complementarity emerged: P. × fraseri appeared to function as a habitat-type plant, potentially providing stable shelter for predatory groups (e.g., spiders and lady beetles), while P. tobira appeared to act as a resource-type plant, potentially attracting a significant rebound of parasitoids (e.g., Xanthopimpla flavolineata) in August. This mid-summer rebound on P. tobira was primarily attributed to its dense evergreen foliage providing a microclimatic refuge, rather than an active flowering resource. Analysis of shared dominant taxa (H. axyridis, Cotesia spp., and E. balteatus) showed highly significant seasonal fluctuations, with peak conservation during the wheat season. This study confirms that P. × fraseri and P. tobira have cross-cycle potential as a “natural enemy bank” in rice–wheat rotation agricultural systems. Their synergistic effects—integrating stable structural shelter with seasonal nutritional subsidies—support the conservation of diverse natural enemy communities throughout the annual crop cycle and significantly enhance the sustained pest control capacity of farmland ecosystems, identifying them as exemplary functional plants for ecological engineering in rice–wheat landscapes and providing a foundation for future studies on biological control efficacy. Full article

Stable nanoemulsions with fine droplets reduce organic solvent use and improve the dispersion of hydrophobic pesticide. However, current studies on deltamethrin nanoemulsion lack systematic formula optimization, performance evaluation and biosafety assessment. This study developed a stable deltamethrin nanoemulsion (Del@Ne) and tested its physicochemical properties, insecticidal activity and non-target safety. In 2025, the effects of surfactant ratio, dosage, preparation temperature and emulsification method on emulsion stability was systematically investigated. The optimal formula contained an active ingredient (2.5% deltamethrin), a surfactant ratio of 8:1 (#601:#500), a 6% surfactant dosage, a 17.25% oil phase (S-100:DMF = 20:3), and deionised water filled to 100%, prepared by adding deionised water to an oil phase containing deltamethrin and surfactants at 40 °C. Del@Ne exhibited small droplet size and good storage stability (TSI ≈ 1), which had better wettability on peach leaves with contact angle falling from 40.4° to 21.6° in 120 s. Del@Ne also gave higher toxicity against Myzus persicae (LC₅₀ = 66.85 mg L⁻¹) than Del@EC (80.69 mg L⁻¹), while showing lower toxicity to zebrafish, earthworms and Harmonia axyridis, as well as better biocompatibility with human L02 hepatocytes. These results provide references for rapid screening of nanoemulsion formulation parameters and also offer insights for the efficient utilization of hydrophobic pesticides. Full article

Females of predaceous ladybirds use sensing chemicals in larval tracks as an oviposition-deterring pheromone to avoid cannibalism of eggs. We hypothesized that larvae would also respond to the presence of conspecific tracks by slowing their developmental rate and delaying pupation, thereby reducing the time spent as a defenseless pupa in the presence of feeding conspecifics. We reared larvae of the harlequin ladybird Harmonia axyridis in dishes that were replaced daily by a clean one (C) or continuously in a dish with larval tracks accumulated (P). We used three larval densities (1, 4, 8 larvae per dish) for both regimes (C1, C4, C8, P1, P4, P8). We measured the developmental time of the fourth larval instar, pupae, and fresh adult body mass. Developmental time increased at the highest density in the combination C8 but remained unchanged across densities in the dishes with pheromone (P1–P8). Body mass was significantly lower at the highest density in both regimes (C8, P8) and was slightly higher in the presence of pheromone (P). Ladybird larvae respond independently of their density and of the presence of pheromones. The compounds present in the tracks, previously known as oviposition-deterring pheromone, may be associated with a buffering effect on density-related developmental delays. Full article

The mass rearing of natural enemy insects is a cornerstone of effective green pest control, making the development of optimized artificial diets critical for sustaining large populations. However, existing artificial diets often have limitations, including inhibitory effects on the reproductive development of natural enemies. In this study, we innovatively incorporated 20% catalpol into the artificial diets for Harmonia axyridis, aiming to comprehensively assess the effects of such dietary regimens on larval development, reproductive performance, and the regulation of energy metabolism in H. axyridis. Our results demonstrated that catalpol supplementation significantly shortened the duration of the 4th instar larval and pupal stages and increased pupal weight. Furthermore, catalpol treatment enhanced reproductive capacity, as evidenced by increased fecundity, improved hatching rate stability, and enhanced ovarian development. This effect was directly correlated with the significant upregulation of the vitellogenin genes Vg1 and Vg2 and their receptor gene VgR at 3 days post-emergence. Regarding energy metabolism, catalpol supplementation led to increased glycogen reserves and glucose content. The expression of the membrane-bound trehalase enzyme gene TRE2 was significantly higher than that in the control group, and the expression level of the soluble trehalase enzyme gene TRE1 also showed a significant increase. These findings indicate that catalpol effectively optimized energy metabolism, thereby accelerating developmental processes and enhancing reproductive capacity. In this study, we elucidated the mechanism by which catalpol regulates physiological metabolism in predatory natural enemy insects. For the first time, catalpol was incorporated into the artificial diet of H. axyridis as a synergistic component, significantly enhancing its growth, reproductive capacity, and energy metabolism. These findings provide a scientific basis for developing efficient artificial feeding systems and improving the field adaptability of natural enemy insects. Full article

As an important natural enemy insect, Harmonia axyridis has significant biological control effects on a variety of pests such as aphids in agroforestry ecosystems. The large-scale application of H. axyridis has long been limited by the unstable supply of natural prey, poor rearing of alternative prey and artificial diets, and high costs. In this paper, we review the research progress on the effects of alternative prey and artificial diets, and present the results and shortcomings of H. axyridis rearing. Focusing on the nutritional requirements of H. axyridis and the nutrient composition of natural prey, the paper aims to analyze and optimize the core components of artificial diets, develop diet formulations that are highly efficient, low-cost, support the ladybird throughout its complete life cycle, and identify the key factors for breaking the bottleneck of large-scale reproduction of H. axyridis, with a view to facilitate the industrialization of H. axyridis, enhancing the efficacy of biocontrol, and providing references to the development of diets for other natural enemy insects. Full article

Background/Objectives: The PB family of “cut-and-paste” DNA transposons shows great promise as genetic manipulation tools while significantly impacting eukaryotic genome evolution. However, their evolutionary profile in beetles (Coleoptera), the most species-rich animal order, remains poorly characterized. Methods: A local tBLASTN search was conducted to mine PiggyBac (PB) transposons across 136 coleopteran insect genomes, using the DDE domain of the PB transposase as the query. Multiple sequence alignment was performed with MAFFT, and a maximum likelihood phylogenetic tree of the transposase DDE domains was constructed using IQ-TREE. Evolutionary dynamics were analyzed by means of K-divergence. Results: Our study reveals PB transposons are widely distributed, highly diverse, and remarkably active across beetles. We detected PB elements in 62 of 136 examined species (45%), classifying them into six distinct clades. A total of 62 PB-containing species harbored intact copies, with most showing recent insertions (K divergence ≈ 0), indicating ongoing transpositional activity. Notably, PB elements from Harmonia axyridis, Apoderus coryli, and Diabrotica balteata exhibit exceptional potential for genetic tool development. Structurally, intact PB elements ranged from 2074 to 3465 bp, each containing a single transposase ORF (500–725 aa). All were flanked by terminal inverted repeats and generated TTAA target site duplications. Conclusions: These findings demonstrate PB transposons have not only shaped historical beetle genome evolution but continue to drive genomic diversification, underscoring their dual significance as natural genome architects and promising biotechnological tools. Full article

Light is a fundamental ecological cue for insects, influencing physiological rhythms and behavior. We investigated how varying light intensities affect locomotion and foraging in H. axyridis color morphs, and examined the role of visual opsins. Three adult female morphs were assayed under white light at 1000, 5000, and 10,000 lx. Higher light intensity significantly elevated body temperature and locomotor activity across morphs, with the inherently dark f. conspicua morph exhibiting the greatest increases. Predation rates on pea aphids trended upward with intensity but differed significantly by morph: f. conspicua beetles consistently consumed more prey than f. succinea. RNAi knockdown of the UV-sensitive opsin HaUVSop-2 significantly reduced the crawling distance of satiated beetles under 5000 lux white light. Correspondingly, supplementation of white light with blue light (short wave) enhanced movement, whereas red supplementation increased aphid consumption. These results suggest that Short-wavelength light has the potential to stimulate the dispersal of ladybirds, whereas long-wavelength light may enhance predation on prey by increasing microenvironment temperature or improving prey recognition. We conclude that light intensity and spectrum jointly modulate H. axyridis behavior in a morph-dependent manner, mediated in part by visual opsins. Melanic morphs leverage thermal melanism to gain higher activity under bright light, implying an evolved trade-off between dispersal and stress tolerance. Our findings have practical implications: tailored lighting (e.g., blue-enhanced illumination to stimulate predation and dispersal of H. axyridis) could improve biological control efficacy in agroecosystems. Full article

Schizaphis graminum is the most important pest of wheat, and its feeding harm not only affects photosynthesis but also causes diseases, posing a serious threat to wheat production. We measured the contact killing and fumigation activities, population changes, enzyme activities, and nanoemulsion physicochemical property of Eupatorium fortune essential oil (EFEO) and pyrethrin against S. graminum and its natural enemy (Harmonia axyridis). Toxic effects of EFEO and pyrethrin increased with increasing concentration. After 24 h of contact killing, the LD₅₀ of S. graminum were 9.23 and 0.02 μg/head, respectively. Harmonia axyridis were 36.71 and 0.07 μg/head. The fumigation of EFEO LD₅₀ on S. graminum was 9.779 mg/L (y = 2.88x − 2.852). EFEO contains 28 chemical components, including l-Caryophyllene, Lily aldehyde, α-Terpineol, and Cineole. EFEO LD₅₀ significantly reduced the adult longevity, nymph production, and nymph production duration of the F0 S. graminum, while there were no significant differences in various parameters of offspring. The activity of acetylcholinesterase, glutathione-S-transferase, and carboxylesterase is significantly affected. The population decline rate of EFEO nanoemulsion is significantly higher than that of EFEO. This research aims to clarify the toxic effect of EFEO on S. graminum, providing a scientific basis for developing new plant essential oil preparations and nano preparations. Full article

RNA interference (RNAi) represents a promising pest control strategy, applicable to both insect-resistant genetically modified (IRGM) crops and sprayable RNAi insecticides. These products can achieve sequence-specific gene silencing and require rigorous environmental risk assessment (ERA) prior to approval. However, current environmental safety assessments of RNAi products and other RNAi experiments frequently use double-stranded EGFP (dsEGFP) as a negative control, while suitable RNAi-based positive controls are lacking. Sometimes conventional chemical toxins (e.g., chlorpyrifos) or protein inhibitors (e.g., trypsin inhibitors) are used as substitutes, but their distinct mechanisms, persistence, and metabolism make them inappropriate for RNAi-specific evaluations. In this study, we evaluated the suitability of RNAi-based positive controls for assessing non-target effects on Harmonia axyridis, a widely distributed predatory beetle used as a bioindicator in biosafety assessments. Under laboratory conditions, we tested one microRNA (miR-92a) and two double-stranded RNAs (dsHaSnf7 and dsHaDiap1) for their effects on H. axyridis. Injection of miR-92a showed no significant difference in mortality compared to controls, whereas dsHaSnf7 and dsHaDiap1 significantly reduced survival rates and target gene expression, as confirmed by qPCR. These findings suggest that HaSnf7 and HaDiap1 are suitable candidate genes for establishing RNAi-specific positive controls in environmental risk assessments of RNAi-based products. Full article

Although traditional genetically modified (GM) cotton has reduced lepidopteran pests, secondary pests such as Adelphocoris suturalis Jakovlev (Hemiptera: Miridae) have become increasingly problematic. RNA interference (RNAi)-based insect-resistant plants offer a promising alternative, but their potential ecological risks, particularly within the plant–pest–natural enemy framework, require comprehensive evaluation. As a key natural enemy in cotton agroecosystems, Harmonia axyridis Pallas (Coleoptera: Coccinellidae) plays a vital role in regulating pest populations and thus serves as an important non-target insect for environmental risk assessment. In this study, dsAsFAR transgenic cotton and the non-target insect H. axyridis were used to evaluate potential ecological risks. Based on the sequences of the HaFAR, AsFAR, and GFP genes, dsAsFAR, dsHaFAR, and dsGFP were synthesized in vitro and incorporated into artificial diets fed to H. axyridis, along with a ddH₂O control group. No significant differences were observed among the treatments across various developmental stages. Furthermore, H. axyridis was fed aphids that had been reared on either transgenic or non-transgenic cotton plants cultivated in a greenhouse. The findings indicated no significant differences in the growth, development, predatory ability, or fecundity of H. axyridis. These results suggest that transgenic dsAsFAR cotton targeting A. suturalis poses no detectable adverse effects on H. axyridis, supporting the environmental safety of RNAi crops within a plant–pest–natural enemy ecological interaction framework. Moreover, the dsAsFAR expressed in transgenic cotton was not effectively transferred through the food chain to affect homologous gene expression in H. axyridis. Full article

Insect metamorphosis is a complex developmental process regulated by hormonal signaling and gene transcription. To elucidate its transcriptional regulatory mechanisms, we examined chromatin accessibility dynamics during metamorphosis in two holometabolous insects, Harmonia axyridis and Drosophila melanogaster, using ATAC-seq. Our analysis revealed distinct stage-specific chromatin accessibility patterns, with peak accessibility during the prepupal stage in H. axyridis and the wandering larval to prepupal transition in D. melanogaster. Through analysis of differential accessibility regions (DARs), we identified enrichment of metamorphosis-related processes including cell morphogenesis, tissue remodeling, and hormone signaling pathways via Gene Ontology and KEGG pathway analyses. Integration of chromatin accessibility with gene expression data revealed 608 conserved genes exhibiting coordinated accessibility and expression changes across both species. Additionally, we constructed a regulatory network centered around four key transcription factors (dsx, E93, REPTOR, and Sox14) that form core regulatory modules controlling metamorphosis. This study provides novel insights into the epigenetic landscape of insect metamorphosis and establishes a foundation for understanding the transcriptional regulatory mechanisms governing this critical developmental process. Full article

In the scenario that requires the biological control of pests using predatory enemies, predators not only prey on pests directly but also can affect the population fitness of pests through indirect non-consumptive effects (predation risk effects). However, the impact of predation risk effects varies depending on the mode of stress imposed by natural enemies and the state of the stressed pests. Herein, we exposed aphids (Periphyllus koelreuteriae) at different stages to various cues from the multicolored Asian lady beetle (Harmonia axyridis) to assess the effects of different predation risks on P. koelreuteriae development and reproduction. We found that the effect of predation risk on aphid developmental time was clearly stage-dependent. When 1st-instar nymphs were exposed to predator cues, their developmental time was prolonged only in the early stages (1st–3rd instar nymphs). Similarly, when third-instar nymphs were stressed, only the current stage (third instar) showed a developmental delay, while fourth-instar nymphs and adult aphids were not significantly affected. Additionally, aphids at different stages perceive predation risk differently. Nymphs cannot recognize visual cues from predators, but can perceive odor cues. In contrast, adult aphids are sensitive to a variety of predator cues, including visual ones. Predation risk caused aphids to shorten their adult lifespan and reduce reproductive output, but it increased the proportion of diapause offspring. This study highlights the importance of considering how predation risk affects multiple life stages and physiological changes, which are important for gaining insights into the mechanisms of predator–prey interactions and for comprehensively assessing the ability of lady beetles to regulate aphid populations. Full article

This study investigated the impact of sublethal concentrations of dinotefuran on the predatory behavior and detoxification enzyme activity of Harmonia axyridis, aiming to establish a theoretical foundation for the conservation and utilization of natural enemies and the effective management of wheat aphids. This study treated wheat aphids with sublethal concentrations (LC₂₀ and LC₃₀) of dinotefuran via the leaf dipping method and subsequently used them as prey for the fourth-instar larvae of H. axyridis. The predation amount, instantaneous attack rate, handling time, daily maximum predation amount, and detoxification enzyme activity of H. axyridis were statistically analyzed. The results indicated that the predation of H. axyridis on wheat aphids conformed to the Holling II disc equation. Moreover, in comparison to the control group, the handling time of H. axyridis on wheat aphids was extended, and at the same time, the instantaneous attack rate, maximum daily predation amount, and predation efficiency were all diminished. After the ingestion of LC₂₀- and LC₃₀-dinotefuran-treated aphids, the carboxylesterase levels in H. axyridis were not significantly different from the control, with levels 0.97-fold and 0.94-fold that of the control, respectively. Glutathione-S-transferase (GST) demonstrated an induction impact compared to the control, reaching 1.96- and 1.47-fold higher than the control, respectively. The activity of mixed-functional oxidase (MFO) demonstrated an induction effect compared to the control, measuring 1.98- and 3.04-fold higher than that of the control, respectively. Consequently, the predation function and detoxification enzyme activity of H. axyridis were influenced when consuming wheat aphids treated with sublethal concentrations of dinotefuran, with significant variations across different concentrations, potentially reflecting the survival strategy of insects under dinotefuran stress. Full article

Heavy metal pollution, particularly cadmium (Cd) contamination in water and farmland, might accumulate in natural insect enemies through the food chain. In response to this heavy metal stress, natural enemy insects adapt by altering their metabolism and behaviors. As a result, this investigation aimed to elucidate how the development, reproduction, and feeding of Harmonia axyridis Pallas (Coleoptera: Coccinellidae) are affected under Cd contamination. Compared to the control group, the developmental period of H. axyridis was prolonged, with decreased survival, predation, and body weights. Notably, adult insects exhibited deformation, including molting difficulties and wing deformities, which indicated reduced fitness. The ovarian development of female insects was delayed with reduced size, and the pre-oviposition period was prolonged under Cd contamination. Additionally, the hatching rate of offspring was significantly reduced. The Vitellogenin 1 (Vg1) and Vitellogenin 2 (Vg2) exhibited considerable changes throughout their developmental stages. Our results confirmed that the accumulation of Cd has a significant impact on the growth, development, and normal molting of H. axyridis, affecting the reproduction of H. axyridis. The aforementioned results provide valuable insights into the potential ecological effects of Cd accumulation on the food chain, which can inform strategies for pest control, ecosystem stabilization in rice fields, and potentially novel bioremediation approaches. Thereby establishing a theoretical foundation for pest control and ecosystem stabilization in rice fields under Cd contamination while simultaneously providing novel insights for bioremediation strategies. Full article