Sweet corn yield formation is highly sensitive to biotic stress during specific growth stages. However, quantitative evidence linking fall armyworm (FAW; Spodoptera frugiperda [J. E. Smith]) infestation intensity, crop phenology, insecticide input intensity, and marketable yield response remains limited under tropical conditions. Here, we evaluated sweet corn yield loss and farmgate income responses to FAW infestation across key growth stages under different insecticide input levels in Hainan, China. Field experiments first compared the efficacy of four commonly used insecticides (chlorfenapyr, spinetoram, chlorantraniliprole, and cyantraniliprole) against FAW infestation to identify an effective reference insecticide, after which multi-frequency application trials were conducted to quantify yield loss and net farmgate income responses under different application frequencies and timings.Results showed that yield loss declined with increasing insecticide input, however, yield gains plateaued beyond moderate application levels, resulting in diminishing marginal returns in net farm income. Controlled cage experiments revealed strong growth stage–dependent yield sensitivity of sweet corn to FAW infestation, with early vegetative (V4–V6) and reproductive (VT–R1) stages as periods of high crop sensitivity, with greater yield losses per unit pest infestation than mid-vegetative stages. Across the 2021 and 2022 seasons, corresponding economic thresholds (ETs) ranged from 7.77–13.10 larvae per 100 plants at V4–V6, increased to 17.47–33.25 and 24.89–46.52 at mid-vegetative stages (V8–V10 and V12–V14), and declined to 12.44–21.78 at VT–R1. By linking stage-specific yield response functions with input intensity and economic outcomes, this study demonstrates that sweet corn yield and income responses to FAW infestation are strongly growth stage dependent. Aligning insecticide input intensity with stage-specific crop sensitivity, rather than pest presence alone, provides a quantitative basis for improving yield stability and economic performance in tropical sweet corn production systems while avoiding unnecessary chemical inputs.

The liquid oxygen subcooler is a key unit for the deep cooling, storage, and transportation of liquid oxygen. Its frequent start–stop operation under liquid nitrogen bath conditions introduces potential risks to service reliability. This study employs a thermo-structural sequential coupling approach to evaluate the stress behavior of ABS components in a flat plate-fin heat exchanger during the pre-cooling, heat-exchange, and recovery stages. Based on the maximum shear stress (Tresca) criterion, the evolution of principal stresses in the brazed layer under liquid nitrogen bath conditions was analyzed, and a conservative assessment of the material’s fatigue behavior was conducted. The results indicate that the equivalent stress is governed by the third principal stress, originating from the thermal compression effect induced by low-temperature constraint shrinkage. During the heat exchange phase (2700 s), the inlet equivalent stress reached 93.49 MPa, which is below the 258 MPa limit, falling within Region 1. Local stress concentration is primarily driven by thermal loading, with brazing layer thickness, curvature radius, and liquid oxygen pressure serving as key control variables. Under a safety factor of 1.15 (107 MPa), fatigue testing exceeding 1.5 million cycles has confirmed the static safety and operational reliability of the ABS.

Rice viral diseases are emerging threats to tropical agroecosystems, yet their spatiotemporal dynamics and transmission ecology remain poorly understood. From 2021 to 2023, systematic field surveys were conducted across 13 rice-growing regions of Hainan Island, China, to assess virus incidence, diversity, and vector associations. Six known rice viruses were detected via RT-PCR, and virome profiling was performed using rRNA-depleted transcriptome sequencing. Brown planthopper (Nilaparvata lugens, BPH) abundance and virus-carrying rates were measured to evaluate their association with rice ragged stunt virus (RRSV) outbreaks. Virus incidence varied markedly across ecological zones and seasons: the semiarid to semihumid transitional zone showed the highest infection rates (approximately 45%), while humid and mountainous areas showed minimal detection. Incidence peaked in summer and autumn and was significantly higher in late-season rice. Virome analysis identified 18 RNA viruses, including nine novel species, spanning multiple viral families. Twelve viruses were detected in BPH and seven in rice, with RRSV being the most prevalent in both. Correlation analysis revealed a strong association between RRSV incidence and BPH virus-carrying rate (R 2 = 0.40, P < 0.001), but not with vector abundance. These results underscore the ecological and vector-related drivers of rice virus epidemics in tropical systems and support viruliferous vector monitoring as a tool for disease forecasting.

Efficient ortho-para hydrogen conversion is essential to suppress spontaneous heat release and boil-off losses during cryogenic liquid hydrogen storage and pre-liquefaction processes. In this study, a novel catalyst-filled wavy plate-fin heat exchanger (CFHE) is proposed to simultaneously enhance heat transfer and ortho-para hydrogen conversion under cryogenic conditions. Compared with conventional straight-fin configurations, the wavy-fin structure introduces controlled flow perturbations and increased specific surface area, thereby intensifying transport processes. Three-dimensional computational fluid dynamics (CFD) simulations, using the SST k-omega turbulence model, coupled with an ortho-para hydrogen conversion kinetic model were performed to quantitatively investigate the effects of key geometric parameters and catalyst loading on hydrogen conversion, heat transfer, and pressure drop within a Reynolds number range of 941-1577 and a temperature range of 35-20 K. Within the same CFHE configuration, the para-hydrogen fraction remains nearly unchanged without catalyst but increases significantly with catalyst loading. However, the catalyst reduces the global average Colburn j-factor by about 25%. Despite higher friction losses, the outlet-inlet temperature difference decreases to about 0.866 times that of the non-catalyst case, indicating improved temperature uniformity. A comprehensive performance index e, integrating heat transfer enhancement, flow resistance, and conversion efficiency, was introduced and optimized using a genetic algorithm. The optimized CFHE achieves an outlet para-hydrogen fraction exceeding 95% of the thermodynamic equilibrium value while maintaining hydrogen entirely in the gaseous phase to avoid catalyst deactivation. Overall, the catalyst-packed wavy channel configuration demonstrates superior conversion efficiency, enhanced thermal uniformity, and improved overall performance compared with straight-fin structures, providing quantitative design guidance for high-performance heat exchangers in cryogenic hydrogen liquefaction systems.

The coconut leaf beetle (CLB), Brontispa longissima, is a major threat to coconut production worldwide, causing widespread and important losses throughout the tropics. Two eulophid parasitoids, larval parasitoid Asecodes hispinarum and pupal parasitoid Tetrastichus brontispae, are the dominant natural enemies of CLB. However, the combined use of these species for biocontrol has not been systematically explored. We analyzed the interactions of A. hispinarum and T. brontispae and evaluated possible deployment strategies by determining the outcomes of releases under realistic agricultural conditions. Our laboratory studies showed that the concurrent release of the two parasitoid species did not reduce either species lifespan or reproductive output, and it significantly enhanced the impact on CLB. A 3:1 ratio of A. hispinarum to T. brontispae, a 10:1 parasitoid-to-pest ratio, and a regimen of five consecutive monthly releases proved to be the most effective strategy in the laboratory. When this combined release approach was used in field trials over a two-year period, there were significant reductions in pest densities and higher parasitism rates than single-species releases. This study highlights the potential of integrating multiple parasitoid species to improve biological control programs.

Understanding how population density influences the biological traits of migratory pests is essential for predicting their spread and developing effective control strategies. While cannibalism is a well-documented survival behavior under high-density conditions, its physiological consequences remain poorly understood. Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), a globally invasive pest with high reproductive and migratory capacity, displays substantial behavioral and physiological plasticity in response to population stress. In this study, we investigated the effects of density-induced cannibalism on flight and reproductive traits in S. frugiperda using integrated biological assays and multi-omics approaches. Cannibalism significantly accelerated larval development and enhanced energy production; however, it resulted in long-term fitness costs, including reduced fecundity, impaired flight performance, and shortened adult lifespan. Integrated transcriptomic and metabolomic analyses revealed a coordinated physiological reallocation under cannibalistic stress, particularly in females. Notably, 20-hydroxyecdysone (20E) was upregulated in larvae, facilitating rapid molting, while both juvenile hormone III (JH III) and 20E were markedly downregulated in adults, corresponding with suppressed reproductive and flight capacities. These results suggest that early-life density stress triggers hormonal reprogramming that promotes immediate developmental benefits at the expense of adult performance. Our findings shed light on the life-history trade-offs associated with cannibalism and provide new insights into the ecological adaptability of S. frugiperda, offering a foundation for density-responsive pest management strategies.

Recent advancements in superhydrophobic surfaces have demonstrated improvements in condensation efficiency by promoting droplet detachment. However, the effectiveness of these surfaces in the low-temperature and low-pressure conditions typical of ocean thermal energy conversion (OTEC) systems remains underexplored. This study addresses that gap by developing a superhydrophobic surface modification scheme to promote dropwise condensation under low-temperature and low-pressure conditions. Superhydrophobic surfaces were created on 304 stainless steel samples using a spray method with nano SiO2+PDMS (polydimethylsiloxane), achieving a maximum contact angle of 154 degrees. On the OTEC-VMD (vacuum membrane distillation) platform, the modified plate with SiO2 and PDMS mass fraction of 3.66%, an inlet temperature of 29 degrees C, and a vacuum pressure of 1.77 kPa achieved a condensation enhancement ratio of 34% and an overall heat-transfer coefficient of 1043.2 W/(m2 K), a 33.65% increase relative to the unmodified plate. Under conditions of a SiO2 mass fraction of 2.47%, PDMS mass fraction of 3.66%, steam generation rate of 23 L/h, inlet seawater temperature of 29 degrees C, and vacuum pressure of 1.77kPa, the modified plate achieved a condensation enhancement ratio of 36.7%, accompanied by a water-production flux of 7.78 kg/h/m2. Steam generation rate and vacuum pressure significantly influenced water production.

The large-scale utilization of ocean thermal energy necessitates cost reduction, which is achievable primarily through system scaling. In this context, this study explores megawatt-scale turbine technology as a key enabler for the commercialization of ocean thermal energy conversion (OTEC) systems. A compact 1 MW radial inflow turbine was designed and modeled, with particular attention to enhancing performance and minimizing system footprint. To meet these requirements, a novel non-azeotropic working fluid mixture-ammonia/R1123 at a mass ratio of 0.76/0.24-was proposed to optimize thermodynamic efficiency. The turbine design process involved the preliminary optimization of key geometric parameters using a particle swarm optimization (PSO) algorithm, followed by detailed three-dimensional computational fluid dynamics (CFD) simulations. Spontaneous nucleation theory was employed instead of conventional equilibrium-based models to capture the nonequilibrium condensation more accurately during ammonia wet expansion, representing a novel approach not previously reported. Under optimal operating conditions, the turbine achieved an isentropic efficiency of 91.74 % and an output power of 1049.91 kW, thereby fulfilling the design objectives. The maximum supersaturation ratio was calculated to be 1.008, below the threshold for spontaneous droplet nucleation, indicating that wet expansion was successfully avoided. Furthermore, off-design performance analyses confirmed the turbine's operational robustness across varying conditions, demonstrating its practical feasibility for integration into large-scale OTEC systems.

IntroductionThrips are key vectors for plant viruses, representing a significant challenge to the cultivation of cucurbits and other vegetables in tropical agriculture. This study investigates the diversity of viromes carried by thrips and their ecological roles in viral epidemics affecting specific crops.MethodsWe identify thrips populations in tropical regions and perform a comprehensive virome analysis through high-throughput sequencing.ResultsOur findings reveal that the predominant thrips species associated with these crops are Frankliniella intonsa, Thrips palmi, and Megalurothrips usitatus. The sequencing efforts identified 19 viruses within these thrips, including previously undocumented viruses, such as a double-stranded RNA virus and several positive- and negative-sense single-stranded RNA viruses. Notably, detection rates of specific plant viruses—Melon yellow spot virus (MYSV), Watermelon silver mottle virus (WSMoV), and Telosma mosaic virus (TeMV)—exhibit significant correlations with thrips population density in cucurbits and other vegetables.DiscussionThis study lays the groundwork for future research into the ecological relationships between thrips and plant viruses, offering valuable insights for developing targeted disease management strategies in tropical agricultural systems.

Emamectin benzoate is a highly effective neurotoxic insecticide widely used to control pests, including Spodoptera frugiperda (Lepidoptera: Noctuidae) which is an invasive insect spreading worldwide. However, the toxicological mechanism has yet to be fully elucidated. Particularly, the contribution of host gut microbiota in emamectin benzoate-killing activity had less explored. Here, we demonstrated that the gut microbiota triggered the toxicity of emamectin benzoate in S. frugiperda. Emamectin benzoate changed the diversity and abundance of gut microbiota. It reduced the abundance of immune-related microbes and genes, which disrupted the balance of antioxidant enzymes in the gut and destroyed the gut morphology. Simultaneously, emamectin benzoate reduced the microorganisms abundance of decompose polysaccharides and the gene abundance of active carbohydrate enzyme which affected the metabolic function and growth of insects. Most importantly, emamectin benzoate stimulated the abundance of enzyme genes involved in the anabolism of gamma-aminobutyric acid by the microbes and catalyzing the production of more gamma-aminobutyric acid which is the key neurotransmitters leading insects to death. This study first provides evidence for the role of gut microbes in promoting the toxicity of EMB and suggests gut microbes as a potential target for insecticide development.

This paper builds upon a previously proposed novel OTEC power and water cogeneration system, focusing on optimizing and verifying the performance of a radial inflow turbine (RIT) using the non-azeotropic R1224yd(Z)/ R1243zf mixture as the working fluid. The study primarily aims to enhance the circumferential efficiency of the RIT while avoiding local optima in the optimization process. Three optimization algorithms-Particle Swarm Optimization (PSO), Genetic Algorithm (GA), and Grey Wolf Optimization (GWO)-were employed to identify key design parameters, with PSO yielding a maximum circumferential efficiency of 94.13 %. CFD simulations of the preliminary design showed a strong correlation with the optimization results, with parameter errors within 5 % at the design point. The off-design performance of the RIT was also evaluated under varying operational conditions, demonstrating excellent adaptability and minimal performance degradation. To validate the design and simulation, a similarity method for constructing an air-model turbine was proposed. This method successfully addressed challenges related to the OTEC RIT's unique operating conditions, confirming the similarity between the ORC RIT and the model turbine. The optimization algorithms and similarity approach provide valuable insights into the design and performance evaluation of organic working fluid turbines for OTEC systems, providing a basis for the experimental study of the similar air turbine.

The safe and efficient design of dynamic submarine cables is critical for the reliability of floating offshore wind turbines, yet traditional time-domain simulation-based optimization approaches are computationally intensive and time consuming. To address this challenge, this study proposes a closed-loop optimization framework that couples machine learning with intelligent optimization algorithms for a dynamic cable configuration design. A high-fidelity surrogate model based on a backpropagation (BP) neural network was trained to accurately predict cable dynamic responses. Three optimization algorithms—Particle Swarm Optimization (PSO), Ivy Optimization (IVY), and Tornado Optimization (TOC)—were evaluated for their effectiveness in optimizing the arrangement of buoyancy and weight blocks. The TOC algorithm exhibited superior accuracy and convergence stability. Optimization results show an 18.3% reduction in maximum curvature while maintaining allowable effective tension limits. This approach significantly enhances optimization efficiency and provides a viable strategy for the intelligent design of dynamic cable systems. Future work will incorporate platform motions induced by wind turbine operation and explore multi-objective optimization schemes to further improve cable performance.

This study addresses the thermal management and engine compartment optimization of a hydrogen fuel cell multi-purpose vehicle through three-dimensional simulations. A computational fluid dynamics model for the heat dissipation in the engine compartment was developed based on the original design of the vehicle model, and the cooling components (main radiator, secondary radiator, and cooling fan) were validated with experimental data. Under idle and high-speed conditions, the simulated results of heat dissipation in the engine compartment agreed well with the test data, indicating good reliability. Simulation results also revealed significant thermal issues, including severe heat recirculation under idle conditions and reduced air utilization efficiency at high speeds. To mitigate these issues, optimization strategies were proposed through adjusting internal arrangements and modifying external structures. After optimization, temperatures on the main radiator and secondary radiator surfaces were reduced by 7.1% and 2.1%, and airflow through the main radiator and secondary radiator were increased by 22.85% and 16.1% with airflow utilization efficiency enhanced by 38%. Additionally, the driving resistance and the drag coefficient were also reduced by 21% x 10.8%, indicating smoother airflow outside the engine compartment. This approach provides a valuable methodology for thermal management and future optimization of a hydrogen fuel cell vehicle.

Telenomus remus is an egg parasitoid of Spodoptera species, including the major agricultural pest Spodoptera frugiperda. Climatic factors are closely related to the development and population dynamics of such parasitoids. However, the effects of rainfall on the biological performance of this wasp have not be studied. Here, we modeled the effects of different intensities of rainfall (control: 0, light rain: 5.0, moderate rain: 10.2, and torrential rain: 42.8 mm/h; falling over a 30 min period) on the parasitism rate, developmental time, and survival of T. remus on eggs of S. frugiperda. We assessed the effect of rainfall exposure on both T. remus adults and on parasitized S. frugiperda eggs. Simulated rainfall resulted in a notable decline in the number of hosts parasitized by T. remus adults for up to 12 h following rainfall, but the parasitism rate returned to normal within one day after rain ceased. Torrential rain reduced immediate (within 24 h) survival of adults of T. remus females, but there was no subsequent effect on adult survival after rain ceased. When parasitized host eggs were exposed to rain events, some eggs were dislodged. Moderate or torrential intensity rainfall dislodged 12 and 44

Opisina arenosella (Lepidoptera: Oecophoridae) is a major leaf-feeding pest of palm crops that has invaded several tropical and subtropical countries or regions. Habrobracon hebetor (Hymenoptera: Braconidae) is a parasitoid of O. arenosella larvae whose effi ciency in controlling its hosts is inhibited by high temperatures. The body color of this wasp exhibits a plastic response to temperature (melanin fades with increasing temperature). Based on the thermal melanism hypothesis, we proposed that H. hebetor adults with lighter body color would have better biological performance at high temperatures. This paper established the link between the parasitoid's body color phenotype and biological performance. Our results show that exposure to 32 degrees C for more than 3 d during the pupal stage induced almost complete loss of abdominal melanin in H. hebetor adults. At the population level, when adults were held under heat stress (34 degrees C), the percentage of abdominal melanin in the parasitoids was negatively correlated with parasitoid longevity and the number of paralyzed hosts, But, in contrast, melanization was positively correlated with parasitoid fecundity. The yellow-biotype of H. hebetor has higher host control potential in tropical regions. Related aspects of our results also improve understanding the biological significance of plastic body color in insects and provide information on host control by H. hebetor in tropical environments.

Tetrastichus howardi (Olliff), a pupal endoparasitoid of the major agricultural pest Spodoptera frugiperda (J.E. Smith). Laboratory studies were conducted to determine the effect of the temperature and supplementary food on the development and reproduction of this parasitoid on S. frugiperda pupae. The results revealed that T. howardi could complete the life cycle under all five tested temperatures (18, 22, 26, 30 and 34 degrees C), with the most extended longevity (female: 42.83 days; male: 24.37 days) and the most prolonged developmental duration (egg-adult) (52.33 days) at 18 degrees C. Parasitoids that were kept at 26 degrees C had the greatest parasitism rate (72.67%) and the highest net reproductive rate R-0 (56.35), and those maintained at 34 degrees C had the highest emergence rate (92.03%), the greatest number of emerged progeny (58.40) and the highest intrinsic rate of increase r(m) (0.310 d(-1)). Feeding on honey, glucose, and sucrose significantly increased the adult longevity and the progeny production of T. howardi but showed no significant effects on parasitism rate, emergence rate, the developmental duration of progeny, or sex ratio. Parasitoids that fed on glucose lived the longest (21.23 days), and the highest emerged offspring occurred when honey is provided (57.77). These results are instructive for the mass-rearing of T. howardi and field control of S. frugiperda.

In the context of global warming and increasing extreme heat, insect responses to temperature include physiological and biochemical changes such as changes in body color. One challenge in biology is to integrate diverse mechanisms of insect plasticity underlying responses to temperature. Life history and trait trade-offs provide a framework for investigating this issue as it relates to the synergistic optimization of related traits. High temperatures during the pupal stage can induce reductions in melanin levels and affect the body color of Habrobracon hebetor adults, with these changes accompanied by enhanced longevity at the expense of fecundity. In our study, we used transcriptome and metabolome sequencing, antioxidant enzyme (SOD, CAT, POD) assays, and additions of exogenous antioxidants, and we found three important relationships: (1) The establishment of heat tolerance in this parasitoid involved responses of antioxidant systems, biogenic amines, and heat shock protein genes, and this tolerance was induced by heat experienced in the pupal stage, with results in the adult stage. (2) A trade-off existed between survival and reproduction based on energy and resource allocation under heat stress. This relationship was disrupted by feeding adults exogenous antioxidants (glutathione and melatonin), as demonstrated by a simultaneous elevation of survival and reproduction at high temperatures. (3) Parasitoid melanosis-related genes (DDC and AANAT) both participated in the regulation of melatonin synthesis. These results enrich our understanding of the theory of plastic body color differentiation in insects and may provide useful insights for the conservation of parasitoids in tropical regions.

This paper proposes an OTEC-VMD desalination system that fully exploits tropical ocean thermal energy to alleviate freshwater shortages on remote islands, with no need of coupling with other heat sources. Based on an in-depth analysis of the mass and heat transfer theory of the OTEC-VMD desalination, a CFD model is established by embedding a UDF program in commercial software and an experimental prototype with a water production capacity of 1 kg/h is designed and manufactured. The CFD simulation and experimental test results show good agreement, with relative errors around 5 %. The proposed system can stably produce water, demonstrating the feasibility of OTEC-VMD seawater desalination experimentally for the first time. At a warm seawater temperature of 30 degrees C, the water production reaches 1.07 kg/h, achieving the design target. The system's water recovery ratio and specific electrical energy consumption are 0.254 % and 2.62 kWh/m 3 , respectively, and the TDS is lower than 5 mg/L. Compared to low-pressure flashing, the equipment achieves an average volume reduction rate of 94.71 %, making it more suitable for installation and transportation in remote marine locations, with great potential in replacing the low-pressure flashing device in the open -cycle of OTEC power plant to promote the large-scale application of OTEC technology.

This research introduces an integrated ocean thermal energy conversion water and power cogeneration system (OTEC-WPCS), combining a Zeotropic Rankine Cycle (ZRC) with Direct Contact Membrane Distillation (DCMD) for efficient power and water production. The hydrofluoroolefins (HFOs), chosen for their zero ozone depletion potential (ODP) and extremely low global warming potential (GWP), are used as working fluid components in the ZRC. Additionally, DCMD is implemented for freshwater generation. A mathematical model is established, incorporating both thermodynamic and CFD simulations. The goal is to identify optimal operating conditions that maximize the output of the system. By coupling DCMD and ZRC in series, the system's efficiency reaches 8.92 %, an improvement of 5.71 % compared to a standalone ZRC system. This configuration allows for more efficient use of surface seawater heat compared to an ammonia-based Organic Rankine Cycle (ORC)-DCMD system. The enhancements include an increase in power and water production per unit mass flow of surface seawater by 0.55 kW/(kg & sdot;s) and 30 %, respectively. Over 60 % of the system's exergy destruction occurs in the DCMD modules and evaporator, while nearly 80 % of the capital cost is associated with the evaporator, condenser, and DCMD heat exchanger. Enhancing the DCMD module structure and heat exchanger can improve both energy and exergy efficiency, and economic feasibility.

The turbine is a crucial component in harnessing ocean thermal energy (OTE), and the impact of the nozzle on turbine performance is significant. TC-profile nozzles have been proven to operate efficiently in air turbines under high-temperature and high-pressure conditions. However, their performance in ocean thermal energy conversion (OTEC) turbines using organic working fluids (low-temperature and low-pressure) still requires further research. Therefore, we focused on a practical 100 kW OTEC turbine equipped with different types of TC-profile nozzles. Three-dimensional numerical models were established, and the simulation results demonstrated that the turbine efficiency using TC-3A was generally higher than other turbines, reaching an optimal efficiency of 89.4%. The turbine can operate efficiently at deviations from the design point of + 10.27% or -31.39% in mass flow rate, +/- 3 degrees C in inlet temperature, and + 20% or -11.43% in rotor speed during off-design conditions. The results revealed the adaptability of TC-3A nozzles to the OTEC environment and their excellent off-design performance. The study could provide valuable guidance and references for the application of TC-type nozzles in the field of OTEC turbines.