Search Results (472)

Host alternation is a common behavioral strategy among many herbivorous insects. The mulberry longhorn beetle, Apriona germari is a destructive wood-boring pest. The adults exhibit rhythmic host alternation between feeding and oviposition hosts. However, the temporal rhythm and regulatory mechanisms underlying this behavior remain unclear. In the present study, by observing the dynamics of the numbers of A. germari on mulberry (Morus alba, feeding host) and willow (Salix babylonica, oviposition host) trees in a cage, we first found that both females and males began to aggregate on mulberry trees at dawn. Following 18:00 at dusk, the number of females on mulberry declined sharply, whereas the number of males decreased slightly, with a greater proportion of males staying on mulberry. To investigate the role of host volatiles in regulating the host alternation in A. germari, we then carried out two-choice olfactory assays to test whether the behavioral responses of A. germari to the host volatiles from mulberry and willow twigs differed between 04:00 and 08:00 (dawn, aggregated on mulberry) and 18:00 to 22:00 (dusk, dispersed from mulberry). Males were consistently attracted to the volatiles from healthy mulberry at both dawn and dusk, but not to those from willow. Females showed no attraction to the volatiles from either of two hosts at dawn; however, at dusk, they were significantly attracted to willow volatiles. Furthermore, volatiles from feeding-damaged mulberry trees were repellent to both sexes, particularly to males at dawn. These results indicate that the rhythmic host alternation in A. germari is partly mediated by host volatiles and an unidentified male-produced pheromone may be present in this species. Our findings can deepen the understanding of the host alternation in longhorn beetles, and offer a theoretical foundation for developing semiochemical-based, eco-friendly strategies for controlling this pest. Full article

The damage caused by herbivores is generally measured as the amount of leaf tissue consumed, without accounting for the fate of the leftover tissue. As a result, the plant defense mechanisms that promote resistance to herbivore feeding by photosynthetically acclimating the rest of the plant to the feeding spot leaf area have not been well exploited. Plant-insect interactions are now becoming better defined with the development of visualization methods that permit spatial whole-leaf assessment of photosynthetic efficiency after herbivore attack. The purpose of our study was to evaluate the spatial heterogeneity of photosystem II (PSII) function at the whole-leaf level before and after herbivory by the Colorado potato beetles. Twenty minutes after Colorado potato beetle (Leptinotarsa decemlineata) feeding, the maximum efficiency of PSII photochemistry (Fv/Fm) decreased significantly, suggesting photoinhibition due to reduced efficiency of the oxygen-evolving complex (OEC). The decreased quantum yield of PSII photochemistry (Φ_PSII) after feeding, at the neighboring area of the feeding spot and at the rest of the leaf area, was attributed to the reduced efficiency of the open PSII reaction centers (Fv′/Fm′), since there was no change in the fraction of open PSII reaction centers (qp). Nevertheless, plant defense elicitation was activated by the photoprotective mechanism of non-photochemical quenching (NPQ) that reduced the singlet oxygen (¹O₂) formation in potato plants in the neighboring area of the feeding spot and at the rest of the leaf area. In addition, the increased production of hydrogen peroxide (H₂O₂) triggered by this increase suggests that it acted as a signaling molecule in the biotic stress defense response. Full article

The global expansion of tree plantations has led to extensive fragmentation of natural forests, posing significant challenges for biodiversity conservation. Understanding the diversity patterns and underlying mechanisms of ground-dwelling insects in these fragmented landscapes is critical to inform effective conservation strategies. To address this, we sampled ground-dwelling insects using pitfall traps across nine remnant natural forest fragments (“islands”) embedded within a tree plantation matrix in Guangxi, China. We examined insect family-level diversity and community composition in relation to fragment isolation (low vs. high) and size (large vs. small) and explored the mechanisms driving the observed patterns. Our results revealed no significant difference in ground-dwelling insect diversity between low-isolation and high-isolation fragments. However, diversity was significantly lower in smaller fragments compared to larger ones. This reduction was primarily driven by decreased seedling density within smaller fragments, directly reflecting the adverse effects of plantation-driven fragmentation on native seedling establishment. Furthermore, we observed noble shifts in community composition of ground-dwelling insects along both fragment isolation and size gradients. Highly isolated fragments exhibited a decline in phytophagous insects and omnivores (with detritivore-herbivore diets), but an increase in detritivores. Smaller fragments exhibited consistent declines across multiple insect taxa spanning various dietary guilds. The observed changes in ground-dwelling insect composition were driven by shifts in plant (especially seedling) community composition. Our findings reveal a clear cascading effect: plantation-driven fragmentation limits native plant regeneration, and these limitations subsequently propagate to higher trophic levels, profoundly impacting ground-dwelling insects. Effective restoration of plantation-fragmented landscapes requires strategies that both prioritize the preservation of large, continuous forest fragments and promote native seedling recruitment within existing fragments. Full article

Body size is a key trait influencing life history and ecological adaptation, and sexual size dimorphism (SSD) reflects divergent selective pressures acting on males and females. In morphologically conserved insect groups such as Cassidinae leaf beetles, the external similarity between sexes often impedes accurate dimorphism assessment. To address this, we conducted a systematic morphometric study of ten Cassidinae species from the Nanling Mountains—the largest east–west mountain system in southern China—where we definitively assigned sex via genital dissection. We measured body weight, body length, body width, length–width ratio, and corresponding wing traits. Across all species, SSD was consistently female biased, with statistically significant but subtle differences in most traits; body weight exhibited the greatest relative disparity. While this pattern aligns with the fecundity advantage hypothesis, direct fecundity data were not collected. Crucially, interspecific allometric analyses revealed that the scaling of male and female body sizes was statistically indistinguishable from that of isometry, providing no significant support for Rensch’s rule in this female-biased system. Our findings offer foundational insights into SSD evolution in cryptically dimorphic, herbivorous beetles and highlight the need for phylogenetically informed studies across broader geographic and taxonomic scales. Full article

Rice (Oryza sativa) production faces serious threats from multiple biotic stresses, particularly the brown planthopper, rice blast, and bacterial blight. Developing resistant cultivars is the most sustainable control strategy. Compared to race-specific resistance genes, disrupting susceptibility genes often confers broader and potentially more durable resistance. However, engineering broad-spectrum resistance against both insect pests and pathogens by editing susceptibility genes remains challenging. In this study, we employed multiplex CRISPR/Cas9 editing to simultaneously disrupt key susceptibility genes involved in distinct defense pathways: ACS2 (for brown planthopper), Bsr-D1, ERF922 or Pi21 (for fungal blast), and Xa5 (for bacterial blight). Three triple-mutant lines (abx, aex, and apx) were successfully generated, and all exhibited significantly enhanced resistance to brown planthopper, blast, and bacterial blight without compromising major agronomic traits compared to the wild type. Our work demonstrates the feasibility of multiplex susceptibility gene editing as a precise and efficient strategy for breeding rice varieties with synchronized, broad-spectrum resistance to both insect pests and pathogenic diseases. Full article

Rubber (Hevea brasiliensis) plantations constitute the largest artificial ecological forest systems in tropical regions of China, while long-term monoculture has significantly reduced biodiversity, particularly among insect communities. Rubber-based agroforestry systems are widely recognized as a promising approach to improving ecosystem functionality. However, the mechanisms by which different intercropping patterns affect insect community dynamics remain poorly understood. This study systematically evaluated the effects of eight rubber-based agroforestry systems on insect community diversity, functional group composition, and associated environmental drivers. Using rubber monoculture as a control, seven rubber-based agroforestry systems were investigated from April 2024 to March 2025. A total of 94,483 insect individuals belonging to 16 orders, 222 families, and 1560 species were recorded. The results indicate that the rubber–fig (Ficus hirta) and rubber–banana (Musa nana) agroforestry systems supported higher insect richness, diversity, and community stability than other systems, while the more complex rubber–coconut (Cocos nucifera)–fig (Ficus hirta) system exhibited a relatively lower value. Functionally, herbivores dominated the rubber monoculture system. The moderately grazed rubber–forage grass (Brachiaria eruciformis)–black goat agroforestry system promoted predators and detritivores, whereas the rubber–konjak (Amorphophallus bulbifer) agroforestry system attracted more omnivores. The permutational multivariate analysis of variance revealed that insect species composition was primarily negatively driven by canopy cover (R² = 14.65%) and management intensity (R² = 11.54%). The ecological benefits of rubber-based agroforestry systems depend not only on crop species diversity but also on vegetation structural complexity and management practices. It is recommended to promote the rubber–banana and rubber–fig agroforestry systems as optimized models and to enhance insect-mediated ecosystem services by maintaining understory vegetation structure, regulating canopy cover, and implementing low-intervention management practices. Full article

Brassica crops (genus Brassica) represent globally important vegetables and oilseeds, yet are continuously threatened by insect pests that reduce yield and quality. While classical physiological and chemical defense mechanisms such as the glucosinolate–myrosinase system have been well documented, recent advances in genomics and molecular biology are beginning to unravel the genetic basis of insect resistance in Brassica species. Notably, emerging evidence highlights the central role of jasmonic acid (JA) signaling and the transcription factor MYC2 as a master regulator of inducible defense responses, where stress-induced degradation of JAZ repressors releases MYC2 to activate downstream defense genes and secondary metabolite biosynthesis. This review synthesizes the current understanding of defense mechanisms in Brassica against herbivores, highlights identified resistance genes and their functional roles, and examines the knowledge gaps that hinder progress in molecular breeding. We then explore future molecular approaches including high-throughput omics, gene editing, and resistance gene mining that hold promise for designing durable insect-resistant Brassica cultivars. To our knowledge, major insect resistance loci are relatively scarce compared to pathogen-resistant loci. We argue for integrated strategies combining classical breeding, biotechnology, and ecological management to accelerate the development of resilient Brassica germplasm. Full article

Cnidium monnieri (L.) Cusson is a species of Umbelliferae plants, and it is one of China’s traditional medicinal herbs, widely distributed in China owing to its strong adaptability in fields. In this article, the research progress on the taxonomy, distribution, cultivation techniques, active components, analysis methods, antibacterial and insecticidal properties, and ecological applications of C. monnieri was reviewed. The main active components in C. monnieri are coumarins (mainly osthole) and volatile compounds, exhibiting multiple pharmacological effects, e.g., anti-inflammatory, antibacterial, antioxidant, anti-tumor, and immune-regulating effects. Some modern analytical techniques (e.g., HPLC, GC-MS, and UPLC-QTOF-MS) have enabled more precise detection and quality control of these chemical components in C. monnieri. The specific active constituents in C. monnieri (e.g., coumarins and volatile components) exhibit significant inhibitory effects against various pathogenic fungi and insect pests. Simultaneously, the resources provided during its flowering stage (e.g., pollen and nectar) and the specific volatiles released can repel herbivorous insect pests while attracting natural enemies, such as ladybugs, lacewings, and hoverflies, thereby enhancing ecological control of insect pests in farmland through a “push–pull” strategy. Additionally, C. monnieri has the ability to accumulate heavy metals, e.g., Zn and Cu, indicating its potential value for ecological restoration in agroecosystems. Overall, C. monnieri has medicinal, ecological, and economic value. Future research should focus on regulating active-component synthesis, improving our understanding of ecological mechanisms, and developing standardized cultivation systems to enhance the applications of C. monnieri in modernized traditional Chinese medicine and green agriculture production. Full article

Plant nutrient content is spatially and temporally dynamic, exposing insect herbivores to substantial nutritional variability. Such variability can constrain insects to feeding on sub-optimal diets, but it can also allow them to regulate their intake towards an optimal nutrient balance. Nutrient regulation is important in pest management, as the nutritional state of insects may alter their susceptibility to insecticides. Diet macronutrient balance has been shown to significantly affect the susceptibility of Helicoverpa zea larvae to endotoxins produced by transgenic crops containing Bacillus thurigiensis (Bt) genes. However, this was demonstrated using a highly inbred laboratory strain, limiting extrapolation to field populations. Here, we test the impact of field-relevant macronutrient variability on the efficacy of two Bt toxins across three field populations to increase the relevance to resistance monitoring and management. While differences in susceptibility were limited across populations, dietary effects were highly population specific. The Bt toxin that was most affected by diet and the diet that supported optimal survival and performance varied across populations. These findings indicate that nutrition can strongly influence Bt susceptibility, but these effects are influenced by population-level differences. To accurately assess Bt susceptibility in the field, bioassay diets should be tailored to the nutritional ecology of local populations. Full article

Under the background of global climate change, frequent drought events have significantly impacted plant–insect interaction. This study focuses on Ficus microcarpa, an important landscaping and urban greening tree species in tropical and subtropical regions, and its primary herbivorous pest, Perina nuda, by applying the age-stage, two-sex life table theory to systematically evaluate the effects on the life history traits and population dynamics of P. nuda reared on F. microcarpa subjected to different levels of drought stress. The results demonstrated that reared on drought-stressed F. microcarpa significantly altered multiple life history traits of P. nuda. All drought treatments significantly shortened the larval development period. Under both light and severe drought conditions, adult lifespan was prolonged, the total pre-oviposition period was reduced, fecundity per female increased, and generation time (T) was shortened. However, significant increases in pupal weight, intrinsic rate of increase (r), and finite rate of increase (λ) were observed only under light drought stress. The population prediction results indicate that both light and severe drought stress lead to obviously higher population growth rates and larger population sizes at 200 days compared to the control group. These findings suggest that the population fitness of P. nuda is enhanced under light and severe drought stress, potentially increasing the probability of pest outbreaks. This study provides an important theoretical basis and practical advice on forecasting population dynamics and implementing integrated management strategies for P. nuda in the context of climate change. Full article

Sometimes, crop breeding varieties demonstrate high resistance to target insects under laboratory conditions but exhibit significantly low resistance in the field. This research aimed to explain this phenomenon based on inter-species interactions among insects, as herbivory by one insect species can trigger physiological changes in plants that enhance their attraction to other insect species. The striped stem borer (SSB), Chilo suppressalis (Walker), and the brown planthopper (BPH), Nilaparvata lugens (Stål), are pests of rice (Oryza sativa L.) that cause major losses in grain production. In this study, we investigated BPH performance and behavior on the planthopper-resistant rice variety “Mudgo” with pre-feeding of SSB. BPHs showed better growth and development, as well as feeding behavior, on SSB-damaged plants compared to undamaged plants. Then, gene expression and phytohormone analysis revealed that jasmonic acid (JA) biosynthesis was induced by SSB feeding. The JA pathway is a central defense signaling hub in rice responding to chewing herbivores like SSB; however, our findings reveal that its induction can have contrasting ecological consequences, inadvertently reducing resistance to a subsequent piercing-sucking pest (BPH). Finally, we discovered that volatile emissions induced by SSB damage attracted BPH and benefited its development. In summary, we found that JA biosynthesis triggered by SSB herbivory played a vital role in rice defense against BPH. This provides insight into the molecular and biochemical mechanisms underlying BPH preferences for SSB-damaged rice plants. Our study emphasizes the crucial role of inter-species interactions in enhancing host plant resistance to insect pests and evaluating germplasm resistance. These findings can serve as a basis for controlling BPH. Full article

An essential first step to implement a control strategy against herbivorous insects is the monitoring of their populations. The efficacy of pheromone-based traps in capturing herbivorous insects can be enhanced by adding adjuvants and using slow-release dispensers to ensure long-lasting attractiveness. Here, we present datasets from a two-year field monitoring campaign of the invasive brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), using clear sticky traps baited with its aggregation pheromone and a synergist, tested towards different dispensers and adjuvants. Bycatch data for native stink bugs (all Hemiptera: Pentatomidae) and leaf-footed bugs (Hemiptera: Coreidae) are also presented. The R code provided was used to organize data and generate weekly captures or weekly density of both H. halys and non-target species. The information provided in this article may contribute to the optimization of pest control strategies in agriculture. Full article

In response to stresses, jasmonates increase rapidly, leading to plant resistance against necrotrophic pathogens and chewing insect herbivores. Jasmonate biosynthesis is regulated at many levels, including transcriptionally, through alternative splicing, and the phosphorylation of the 13S-lipoxygenase (LOX) that catalyzes an early step in jasmonate biosynthesis. In pepper, transcriptomic analysis of a foliar wounding time course was conducted to deepen our understanding of these regulatory mechanisms. All four CaLOXs are constitutively expressed. CaLOX2, which encodes an enzyme with a Ser in a predicted regulatory phosphosite, shows a rapid but short-lived increase in wound-induced expression. In contrast, CaLOX7, which encodes a protein with a non-phosphorylatable Ala at the phosphosite, shows higher wound-induced expression at 6 h. As well, at this timepoint, there is a predicted increase in exon 4 retention in CaLOX8 transcripts in wounded plants. ChimeraX protein modeling predicts that the retention of exon 4 may negatively affect enzyme activity, possibly by blocking access to the enzyme’s active site. The transcription, alternative splicing, and post-translational regulation of CaLOX enzymes support the dynamic fluctuations observed in the jasmonates, which increase rapidly upon wounding and return to basal levels at 6 h post-stress. Full article

The tea plant (Camellia sinensis) employs inducible chemical defenses against insect herbivores, yet the role of phenylalanine ammonia-lyase (PAL) in this process remains inadequately characterized. This study demonstrates that PAL is essential for tea plant’s direct resistance against the tea geometrid (Ectropis grisescens Warren). Inhibition of PAL activity using 2-Aminoindan-2-phosphonic acid significantly reduced catechins accumulation and promoted larval growth of E. grisescens. Compared to mechanical wounding alone, simulated herbivory feeding (mechanical wounding plus oral secretions) induced higher PAL activity and more pronounced upregulation of CsPAL genes. This response specifically highlighted CsPALb, CsPALd, and CsPALe as core, herbivore-responsive members. Transient silencing of CsPALb in tea leaves led to a significant reduction in the levels of catechin (-)-epigallocatechin and epigallocatechin gallate. Moreover, heterologous overexpression of CsPALb and CsPALd in tobacco (Nicotiana tabacum) enhances resistance to Spodoptera litura. Our results indicate that PAL-mediated phenylpropanoid metabolism is not only critical for herbivore resistance of tea plant, but can also provide valuable gene resources for improving herbivore resistance in other plants. Full article

Plants are naturally exposed to various biotic stresses, including pathogen attacks and insect herbivory, which activate distinct signaling pathways as part of their defense responses. Inoculation with beneficial microorganisms, such as plant growth-promoting rhizobacteria (PGPR), can trigger induced systemic resistance (ISR) in plants, a defense response that resembles the one activated by herbivore attack in terms of signaling pathways and physiological effects. However, these interactions have typically been studied independently, limiting our understanding of their combined effects. In this study, we examined the effects of aphid (Acyrthosiphon pisum) herbivory on Ocimum basilicum plants and assessed how these responses are modulated when the plants are inoculated with the PGPR strain Bacillus amyloliquefaciens GB03, with a particular focus on biochemical and structural defense mechanisms. Aphid herbivory significantly increased total essential oil (EO) content and volatile organic compound (VOC) emission and induced a greater density of glandular trichomes while also modifying the phytohormone profile. In contrast, total phenolic content remained unchanged. When aphid herbivory occurred on GB03-inoculated plants, the effects on defense-related parameters became more pronounced. EO and eugenol contents were further increased compared with inoculated controls, jasmonates remained comparable to levels induced by either factor alone, and SA levels nearly doubled relative to aphid-infested plants. Feeding assays revealed that aphids preferred inoculated plants over controls, a response that may be explained by the increased emission of eugenol in inoculated basil. These results demonstrate that GB03 inoculation modifies several defenses-related responses in O. basilicum upon aphid herbivory, including by hormonal signaling, specialized metabolites accumulation, and structural barriers such as glandular trichomes. These findings suggest that PGPR may contribute to modulating plant responses to herbivory under certain conditions, highlighting their context-dependent influence within plant–microbe–insect interactions. Full article