Search Results (305)

The essential oils obtained by steam distillation of leaves of Piper species have found several applications in bioeconomy due to their various biological properties. Nevertheless, the analysis of essential oils does not provide information regarding the ecologically relevant volatile organic compounds (VOCs) emitted by metabolically active leaves under real-world conditions, challenged or not by herbivore damage. In this study, P. arboreum growing in a highly diverse area was observed as the host of two generalist caterpillars—Gonodonta maria (Erebidae) and Dysodia spissicornis (Thyrididae)—and one Piper-specialist from the genus Eois (Geometridae). The effect of the leaf attack caused by the three different caterpillars on VOCs emission indicated significant and herbivore-specific changes in leaf-induced responses. The profiles of undamaged leaves showed that the two generalist herbivores induced a higher number of single VOCs and of total VOCs emissions by P. arboreum when compared to the herbivory of the specialist caterpillar. Many of the VOCs emitted by herbivore-damaged leaves contained terpenoids that have been previously shown to attract parasitoids, such as (E)-β-ocimene, linalool, DMNT and (E)-β-caryophyllene. All three herbivores significantly altered the VOC profile of P. arboreum leaves compared to undamaged controls, but specific composition signatures were observed, highlighting the complexity of chemical communication at multitrophic levels. 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

Population models offer insights into both theoretical and practical aspects of insect population dynamics. Among the models, stage-structured matrix models are used to describe the population dynamics of insects because the development of insects is by nature stage-structured. Field populations of the pine caterpillar, Dendrolimus spectabilis (Lepidoptera: Lasiocampidae) were monitored in a pine stand located in Dorak-ri, Cheongsan-myeon, Wando-gun, Jeollanam-do, from May 1998 to March 1999, and the pest density was measured as the number of larvae, pupae, or eggs at one-month intervals, excluding the winter season. Life tables and matrix models were constructed based on field observations, and the most vulnerable life stage was identified through sensitivity analysis. The density of the pine caterpillar (number per 1000 cm² branch) was 7.9 on 8 May 1998, and subsequently decreased to 0.5 on 14 March 1999, showing a decreasing trend of caterpillar density. The population growth rate was 0.74, a decreasing trend. The most vulnerable stages were (1) the larvae immediately after hatching and (2) again during overwintering, probably due to indirect mortality caused by humid conditions and activities of natural enemies during winter. Given the significant damage caused by mature larvae in the spring and that the density of the caterpillar after overwintering typically remains stable, forest management requires that the pest density be monitored soon after overwintering to allow decisions about control measures to be taken. Our results showed that a matrix model is useful to describe the population dynamics of the pine caterpillar and to construct suitable management strategies. Full article

Background: Insect metamorphosis is one of the most fascinating developmental processes in the natural world. Complete metamorphosis requires the breakdown and reorganisation of larval tissues and the coordinated construction and development of adult structures. The molecular events that achieve this transformation are, however, incompletely understood, and there is a particular shortage of data describing changes in protein abundance that occur during the process. Methods: Here, using a label-free quantitative bottom-up approach, we perform a novel whole-organism proteomic analysis of consecutive developmental stages of male Bicyclus anynana butterflies as they develop from caterpillars into adults via pupation. Results: Our analysis generated a dynamic reference dataset representing 2749 detected proteins. Statistical analysis identified 90 proteins changing significantly in abundance during metamorphosis, and functional interpretation highlights cuticle formation, apoptosis and autophagy during the pupal stages, and the up-regulation of respiration and energy metabolism upon completion of the fully formed adult. A preliminary search for potential peptide phosphorylation modifications identified 15 candidates, including three proteins with roles in muscle function. Conclusions: The study provides a basis for future protein-level analysis of butterfly metamorphosis and suggests the importance of dissecting the post-translational regulation associated with this fascinating developmental transformation. Full article

The depletion of fossil fuel reserves and the pollution produced by fuel combustion are major concerns in the energy generation sector. Due to this, waste heat recovery has become a stringent objective in this domain. The current study pursues this objective with regard to gas–steam combined cycle power plants, which are currently viewed as the most advanced technology in fossil fuel power generation. The proposed solution for waste heat recovery is to add an organic Rankine cycle (ORC) power system to the gas–steam combined cycle power plant with a Solar Centaur 40 gas turbine, produced by Solar Turbines, a Caterpillar Company (San Diego, CA, USA). The ORC power system is placed along the path of the flue gas, downstream of the heat recovery steam generator of the combined cycle power plant. R1336mzz (Z), R1233zd (E), and R601a were investigated as working fluids. The performance of the ORC system was analyzed as a function of the degree of superheat. The superheating process was proven to be disadvantageous since it led to performance deterioration. The numerical study showed that the overall efficiency of the combined cycle power plant increased up to 0.014 (1.4%) as a consequence of adding the ORC system, which itself achieves a maximum efficiency of 0.133 (13.3%). The annual fuel (natural gas) savings achievable under these conditions were roughly estimated at 398,185 Nm³/year, equating to annual fuel cost savings of approximately 269,000 EUR/year and an 810 t/year reduction in CO₂ emissions. Full article

Gynaephora qinghaiensis is a major grassland pest common in the alpine meadows of the western plateau of China, and its biological behavior is affected by the synergy of a variety of chemicals in the environment. OBPs can dissolve and transport odor molecules such as volatile plant compounds through lymphatic fluid, which plays an important olfactory-to-olfactory role. However, the specific function of OBPs in the interaction mechanism between moths and volatile plant compounds is still unknown. The purpose of this study was to analyze the binding characteristics of GqinOBP10 and its volatile plant compounds in moths and to explore its role in the olfactory perception mechanism of moths so as to study the corresponding target ligands and achieve green control. The purified GqinOBP10 was subjected to fluorescence competitive binding to eight ligands. The 3D modeling of GqinOBP10 was carried out by the SWISS-MODEL website, and the molecular docking was carried out by Autodock 4.2.6 software, and the binding of GqinOBP10 to eight ligands was simulated and verified. The results showed that the cloned strain with the full length of GqinOBP10 was cloned. The fluorescence competition binding results showed that GqinOBP10 had strong binding ability to eight volatile plant compounds, among which the binding ability to 2-Amino-1-phenylethanol and 2-Oleoylglycerol was the strongest, and had high binding ability with the other six ligands. The molecular docking results showed that the binding energy of GqinOBP10 and eight odorant molecules was negative, and all of them could form 1~4 hydrogen bond for binding, among which the binding performance with 2-Oleoylglycerol was the best. The findings suggest that dsOBP10 injection leads to a notable decrease in both the expression levels of GqinOBP10 and the antennal potential response in male and female tissues. This indicates that GqinOBP10 is likely crucial for the localization and recognition of host plants in G. qinghaiensis. By silencing GqinOBP10, the olfactory perception of host volatiles is significantly impaired, highlighting the protein’s importance in the caterpillars’ ability to detect and respond to their environment. These insights provide a valuable basis for developing targeted attractants, potentially enhancing pest management strategies by manipulating olfactory cues in these caterpillars. Further research could explore the specific mechanisms by which GqinOBP10 influences olfactory perception and host plant selection. Full article

Ascoviruses (AVs) are obligate intracellular pathogens that target the larval and pupal stages of lepidopteran insects, specifically moth caterpillars. AVs are unique among viruses in their (i) transmission mode, (ii) gross pathology, (iii) virion ultrastructure, (iv) genomic architecture featuring a remarkable combination of genes, and (v) ability to reprogram host cell death and lipid biosynthetic pathways to generate virion-containing vesicles (VCVs). The metabolically active acellular VCVs are repurposed to complete virogenesis and to facilitate dissemination by endoparasitoid wasps. Since their discovery in the late 20th century, research has focused on these distinctive traits and, to a lesser extent, their potential for biological control. Among AV proteins are the large DNA-binding P64 family, inhibitor of apoptosis-like proteins (IAPs), executioner caspase and caspase-like proteins, and lipid-modifying enzymes, which together drive their novel cytopathology. This review synthesizes current knowledge of AV biology and proposes a framework for understanding VCV formation by integrating predicted viral protein functions with host cellular pathways, including the ceramide–sphingosine-1-phosphate rheostat and apoptosis. Full article

Chinese cordyceps, a highly valued traditional medicine, is formed when the fungal parasite Ophiocordyceps sinensis infects an underground caterpillar (Thitarodes). This interaction progresses slowly, as the larvae have a long developmental period and the fungus requires several months to complete its growth. The medicinal fungus O. sinensis has a complex life cycle that requires successful transformation from blastospores to hyphae for the formation of Chinese cordyceps. Building on our previous identification of diverse microbial communities associated with Thitarodes xiaojinensis larvae, this study investigates the role of host microbiota in enhancing O. sinensis blastospore transformation under in vitro conditions. Cultured supernatant of Fusarium pseudonygamai associated with T. xiaojinensis larvae significantly increased transformation rates by 31.6% after 8 days. Transcriptomic profiling revealed early upregulation of genes involved in energy metabolism, stress response, detoxification, and hyphal morphogenesis (notably CYC1, hmp, gedE, and fahA), supporting the cellular reprogramming required for fungal development. Additionally, mannitol isolated from F. pseudonygamai culture acted as a key promoter of transformation. Further functional assays confirmed that modulation of mannitol biosynthesis genes (M1PDH and MDH) through chemical agonists and inhibitors directly influenced mannitol levels and transformation efficiency. Collectively, these results highlight the pivotal role of microbiota-derived metabolites, particularly mannitol, in regulating O. sinensis transformation, offering potential strategies to improve artificial cultivation of Chinese cordyceps. Full article

A self-sustaining population of birdfoot violet (Viola pedata), a host plant for the threatened western subspecies of regal fritillary butterfly (Argynnis idalia occidentalis) caterpillar, was examined during a single year from April to June 2021 on a small, 3.1 ha dry bluff prairie hillslope within the Whitewater Wildlife Management Area in southeastern Minnesota USA. Assessments were conducted to determine if violet populations on small prairie remnants could support seed collecting to establish new populations nearby. Ten transects and five random plots were used to assess violet density and monitor violet growth, reproductive phenology, and seed production. Violet densities were high (>5 plants/m²), with greatest densities at middle elevations on the hillside in the middle of the prairie rather than near the edges. The total population of birdfoot violets on the hillside was extrapolated from density estimates based on 200, 1-m² plots to be >62,000 plants. Seed set was low (less than one pod per plant) but nearly 400,000 total seeds were produced during the 2021 growing season. More than 3000 seeds (<1% of estimated seed production on the study hillslope) were collected for out-planting to establish a new violet population in nearby Whitewater State Park. Some small bluff prairies in southeastern Minnesota and elsewhere under certain conditions may sustain violet populations large enough to permit seed collecting to establish additional populations during restoration of native prairie communities. These ultimately should provide much needed habitat for regal fritillary butterflies to partially compensate for ongoing habitat losses. Full article

The grassland caterpillar Gynaephora qinghaiensis (Lepidoptera: Lymantriidae) is a dominant pest species in the alpine meadows of the Tibetan Plateau. Elucidating changes in key gene expression patterns will provide molecular insights into the adaptive evolutionary mechanisms of insects. Quantitative real-time PCR (qRT-PCR) is currently the predominant analytical methodology for assessing gene expression levels. However, variability among samples can compromise result reliability. Thus, selecting stably expressed reference genes for target gene normalization under diverse scenarios is critical. To date, suitable reference genes for G. qinghaiensis under varying experimental conditions have remained unidentified. In this study, the transcriptome data of G. qinghaiensis were obtained using the RNA-seq technique, and 13 candidate reference genes were selected. Four independent algorithms—ΔCt, geNorm, NormFinder, and BestKeeper—as well as a comprehensive online platform, RefFinder, were employed to evaluate the stability under six experimental conditions (tissues, developmental stages, sexes, temperatures, starvation, and insecticide treatments). Our findings identified the following optimal reference gene combinations for each experimental condition: RPS18, RPS15, and RPL19 for tissue samples; RPL19, RPS15, and RPL17 across developmental stages; RPS18 and RPS15 for different sexes; RPS8 and EF1-α under varying temperature conditions; RPL17 and RPL15 during starvation; and RPL19 and RPL17 following insecticide treatments. To validate the feasibility of the reference genes, we examined the expression of the target gene HSP60 in different tissues and under different temperatures. Our results established essential reference standards for qRT-PCR with G. qinghaiensis samples, laying the foundation for precise gene expression quantification in the future. Full article

Background/Objectives: Causal inference requires validating the stable unit treatment variance assumption (SUTVA). Whilst antimicrobial-based interventions, being topical chlorhexidine and topical antibiotics prophylaxis (TAP), appear effective in preventing ventilator-associated pneumonia (VAP) among ICU patients receiving mechanical ventilation (MV) within randomized concurrent controlled trials (RCCT), SUTVA has never been tested for this inference. Methods: Caterpillar plots of the VAP incidence proportions for control and intervention groups within RCCTs obtained from recent Cochrane reviews of antimicrobial-based VAP prevention interventions were derived using random effects methods to enable comparison versus the expert VAP incidence reference range (5 to 40%). Results: The summary VAP prevention effect size derived from three categories of 57 RCCTs of antimicrobial-based interventions was recapitulated. The VAP incidences of 24 control groups and 6 intervention group incidences were above, whereas only 1 and 6, respectively, were below the expert VAP incidence reference range (5 to 40%) (p < 0.001; chi-square = 17.42; df = 2). The results after excluding 18 low-quality studies were similar. Paradoxically, the 90% prediction limits in association with the summary control group incidences are each approximately 20 percentage points wider than for those associated with the intervention group summaries. Conclusions: Control group VAP incidences above and more dispersed versus the expert opinion VAP range are common within the Cochrane reviews of antimicrobial-based VAP prevention interventions. Recognition requires an arms-based analysis using caterpillar plots. The SUTVAs that underlie the inference of prevention from the effect size estimates are not valid. Full article

Forests, as one of the most vital ecosystems on Earth, play essential roles in climate regulation, water conservation, and resource provision. However, forest health is threatened by pests, among which the larch caterpillar (Dendrolimus superans) is one of the most destructive defoliators of coniferous forests in northern China. Previous studies have mostly relied on single data sources for pest detection, which are limited by insufficient spectral information or inappropriate selection of sensitive bands, making it difficult to achieve high detection accuracy. Therefore, this study integrates hyperspectral imagery from Zhuhai-1 and multispectral imagery from Sentinel-2, leveraging their high spectral resolution and broad spectral range, thus enhancing discrimination capability. Genetic algorithm (GA) was employed to select optimal features from spectral indices, texture features, and fractional-order derivatives (FOD). Random Forest (RF), Support Vector Machine (SVM), and eXtreme Gradient Boosting (XGBoost) were compared, and model interpretability was further analyzed using Shapley additive explanations (SHAP). The results showed that XGBoost achieved the highest performance, with an overall accuracy and Kappa coefficient of 93.47% and 89.81%, demonstrating superior adaptability. Moreover, the integration of hyperspectral and multispectral data significantly improved detection accuracy compared to using either data source alone. Among the GA-selected features, Band 15 of Zhuhai-1 hyperspectral imagery exhibited strong sensitivity to pest infestation. This study provides a novel and practical approach for forest pest monitoring based on the synergistic use of hyperspectral and multispectral remote sensing data. Full article

Tea is a global commodity, and due to its way of preparation pesticide residues cannot be tolerated. This underlines the importance of non-chemical pest control. Kenya is the third largest global tea producer but the potential of natural enemies against tea pests is unknown. We used artificial caterpillars made of non-drying green plasticine to quantify attack rates by predators on tea canopies at different distances from plantation edges and in the nearby native forest during the wet and dry seasons in three tea-growing mountain regions of Kenya, Kericho, Gatamaiyu and Kakamega. The artificial sentinel caterpillars were readily attacked by arthropods, birds, and sporadically by small mammals. During an exposure time of 24 h, the overall attack rate was 25.0%d⁻¹. Natural enemy activity was higher in the dry (35.3%d⁻¹) than in the wet (16.7%d⁻¹) season. The highest predation pressure was measured in the native forest (41.7%d⁻¹) and gradually decreased with increasing distances into the tea plantation (to 8.3%d⁻¹ at 40 m from the edge). The rate of decrease from the forest edge towards the centre of the tea plantation was steeper for birds than for arthropods, indicating that birds were more reluctant to use this habitat. The potential for natural pest control in Kenyan tea plantations is high, but planting native trees is recommended especially if bird activity inside tea plantations is to be encouraged. Full article

We describe the trophic relationships of tachinid parasitoid flies that attack exophagous, leaf-eating Lepidoptera caterpillars in Área de Conservación Guanacaste (ACG), northwestern Costa Rica over approximately forty years beginning in 1984. The dataset contains more than 34,000 individual tachinid rearings from individual wild-caught caterpillars. Identification of parasitoids and caterpillars up until 2004 was based entirely on morphology. From 2004 onwards most reared specimens were DNA-barcoded and some retroactive barcoding was also carried out with varying degrees of success. Generally, for older specimens, generating good quality-barcodes requires more expensive protocols. Barcoding of reared specimens led to the recognition that many morpho-species were made up of multiple species of flies but those reared from an individual caterpillar were 99.95% a single species. Consequently, estimates of diet breadth of caterpillars and tachinids changed considerably after 2003. The data analysed here were pruned to include only rearings with complete host and food plant data and excluded potentially duplicated rearings and ones whose identification could not be confidently assigned. The cleaned dataset includes 13,735 independent rearings. Chao1 estimates of numbers of tachinid, caterpillar and food plant species suggest that species sampling is 86, 70 and 91 percent complete, respectively. However, this was not the case for bi- and tritrophic interactions which increased linearly with effort. We show that while the tachinids of ACG are more host-specialised than was expected prior to the combined efforts of rearing and barcoding, they have broader host ranges and higher host Shannon diversity indices than either Braconidae or Ichneumonidae. This may be attributable to the effects of the induced host-derived sac enclosing the larvae and their posterior spiracles. Full article

Background: Grassland desertification has garnered significant attention as a pressing issue. Among the key pests affecting plateau meadows, the Gynaephora qinghaiensis (Lepidoptera: Lymantriidae) poses a substantial threat in the Qinghai-Tibet Plateau region, highlighting the urgent need for effective, environmentally friendly control strategies. Insect sex pheromones are increasingly employed in pest monitoring and management. Methods: This study aims to identify and analyze genes associated with sex pheromone synthesis in grassland caterpillars through transcriptome sequencing and tissue-specific expression analysis. Results: A total of 139,599 transcripts and 56,403 Unigenes were obtained from the sex pheromone glands transcriptome database. A total of 31 genes related to sex pheromone synthesis were identified, including 1 ACC, 8 DES, 6 AR, 7 FAR, 5 FAS, and 4 ACT genes. The expression levels of these genes varied significantly across different tissues in both male and female caterpillars (p < 0.05). GqinACC1, GqinDES1, GqinDES4, GqinDES8, GqinAR3, GqinFAR6, GqinACT2, and GqinACT3 exhibited significantly higher expression levels in the female gonads compared to other tissues (p < 0.01). Conclusions: We hypothesize that specific genes play specific roles in the pheromone synthesis pathways of pests, Key genes were identified based on expression patterns for subsequent functional studies. The results of this study offer valuable data support for subsequent investigations into the mechanisms underlying sex pheromone synthesis in G. qinghaiensis. Additionally, these findings may identify potential targets for future research on genes associated with pheromone biosynthesis, which could disrupt their chemical communication and contribute to grassland conservation efforts. Full article