Agricultural Pests Research Articles

In-field disease symptom detection and localisation using explainable deep learning: Use case for downy mildew in grapevine

Diseases and pests in agriculture significantly impact crop yield and quality. Downy mildew (Plasmopara viticola) is a particular noteworthy example in grapevines. Traditional detection methods are laborious, subjective and time-consuming. Consequently, a technological solution based on artificial intelligence, would provide higher levels of reproducibility and sampling. The aim of this work was to develop an interpretable, automated method for detection and localisation of plant disease symptoms under field conditions. Images of the grapevine canopy were taken in 14 commercial vineyard plots under a range of lightning conditions, including both static and on-the-go settings. The images were processed using a sliding window, classifying sub-images into areas with and without downy mildew. Transfer learning, fine-tuning and data augmentation were employed to automate the classification, comparing convolutional neural networks (CNNs) and vision transformers (ViT). Subsequently, the trained model was integrated into the sliding window to localise regions within the canopy images exhibiting symptoms of downy mildew. Model predictions were interpreted using explainable artificial intelligence (XAI) methods. The EfficientNetV2S model achieved an accuracy of 91 % and an F1-score of 0.92 when classifying image areas and an Intersection over Union (IoU) of 0.83 when locating symptomatic areas. This method showed promising results, enabling automatic and explainable detection and localisation of plant diseases in complex conditions. The straightforward labelling process facilitated adaptation to new conditions, making it suitable for different crops and diseases. Integration into mobile platforms could enhance disease management and reduce the spread of pathogens, making a significant advance in agricultural technology.

Characterization of ATP-binding cassette transporters associated with emamectin benzoate tolerance: from the model insect Drosophila melanogaster to the agricultural pest Spodoptera frugiperda.

Multiple families of detoxification genes, including the increasingly recognized family of ATP-binding cassette (ABC) transporters, work together to influence the toxicity of synthetic insecticides and thus their resistance. Effective management of insecticide resistance requires identification of all toxicity-affecting members from each family of toxicity-related genes. Here, we used emamectin benzoate (EB), ABC transporters and Spodoptera frugiperda as a working case to test whether the strategy of 'from the model insect Drosophila melanogaster to agricultural pests' can identify all or most ABC transporter members related to EB tolerance in S. frugiperda. After confirming the involvement of ABC transporters in the toxicity of EB against fruit fly with the ABC inhibitor verapamil, four ABC transporter genes (DmCG3327, DmCG11147, DmCG4822, and DmCG7627) were found to be involved in EB tolerance using RNA interference-based family-wide functional screening. A combination of phylogenic analysis and a reciprocal TBLASTN search identified five S. frugiperda ABC transporter members as homologs (SfABCC4, SfABCG1, and SfABCG23) or one-way best hits (SfABCG4 and SfABCG20) of the four fly ABC genes. Real-time quantitative polymerase chain reaction (qPCR) analysis found that all five S. frugiperda ABC transporter genes were inducible by EB, and expressed in all the developmental stages and larval tissues, but with significant quantitative differences among stages and tissues. A cytotoxicity assay of ABC-overexpressing Sf9 cell lines showed that all the five S. frugiperda ABC transporter genes made Sf9 cells tolerant to EB. This study not only identifies nine ABC transporter genes related to EB tolerance from D. melanogaster (four genes) and S. frugiperda (five genes), but also demonstrates the utility and effectiveness of the 'model to pests' strategy to identify most toxicity-affecting members from a given family of toxicity-related genes. © 2024 Society of Chemical Industry.

Horizontal transmission of a rice bacterial pathogen Pantoea ananatis among plants by rice planthoppers.

Pantoea ananatis is a bacterium commonly found in various agronomic crops and agricultural pests. In this study, we present findings on a genome-reduced strain of P. ananatis, known as Lstr, which was initially isolated from Laodelphax striatellus (small brown rice planthopper, SBPH). We identified Lstr as a plant pathogen causing disease in rice using Koch's postulates. The pathogenicity of Lstr on rice is comparable to that of Xanthomonas oryzae pv. oryzae, the main causative agent of rice bacterial blight. Through a series of experiments involving live insects, molecular investigations, and microscopy, we find that Lstr can accumulate within SBPH. Subsequently, Lstr can be transmitted from SBPH to rice plants, resulting in leaf blight, and can also be transmitted to other SBPH individuals. Collectively, our results suggest that SBPH serves as a vector for P. ananatis Lstr in rice plants. P. ananatis may encounter susceptible insect populations and become endemic through horizontal transmission from these insects. This could also be valuable for predicting future occurrences of bacterial leaf blight in rice and other crops caused by P. ananatis.

Parasitic behaviour and developmental morphology of Anastatus japonicus reared on the factitious host Antheraea pernyi.

The egg parasitoid Anastatus japonicus is a key natural enemy in the biological control of various agricultural and forestry pests. It is particularly used against the brown marmorated stink bug Halyomorpha halys and the emerging defoliator pest Caligula japonica in East Asia. It has been proved that the eggs of Antheraea pernyi can be used as a factitious host for the mass production of A. japonicus. This study systematically documented the parasitic behaviour and developmental morphology exhibited by A. japonicus on the eggs of A. pernyi. The parasitic behaviour of A. japonicus encompassed ten steps including searching, antennation, locating, digging, probing, detecting, oviposition, host-feeding, grooming, and resting. Oviposition, in particular, was observed to occur in three stages, with the parasitoids releasing eggs during the second stage when the body remained relatively static. Among all the steps of parasitic behaviour, probing accounted for the longest time, constituting 33.1% of the whole time. It was followed by digging (19.3%), oviposition (18.5%), antennation (9.6%), detecting (7.4%), and the remaining steps, each occupying less than 5.0% of the total event time. The pre-emergence of adult A. japonicus involves four stages: egg (0 to 2nd day), larva (3rd to 9th day), pre-pupa (10th to 13th day), pupa (14th to 22nd day), and subsequent development into an adult. Typically, it takes 25.60 ± 0.30 days to develop from an egg to an adult at 25℃. This information increases the understanding of the biology of A. japonicus and may provide a reference for optimising reproductive devices.

Deterrent Effects of Clary Sage Oil and Two Major Constituents against Drosophila suzukii (Diptera: Drosophilidae).

Drosophila suzukii (Diptera: Drosophilidae), spotted-wing drosophila, poses a significant threat to soft-skinned fruit crops in the Americas, Europe, Africa, and Oceania, as well as in Asia. The application of chemical insecticides is the primary control strategy for D. suzukii; however, resistance has developed with the indiscriminate use of chemical insecticides. Essential oils, considered potential alternatives to pesticidal strategies, exhibit potent toxic and sublethal behavioral effects against numerous pests, including D. suzukii. Clary sage oil repels a variety of agricultural and household pests; however, whether it has a repellent effect against D. suzukii remains unknown. Here, we found that clary sage oil exhibited dose-dependent repellency against D. suzukii adults in a T-maze assay, a two-choice assay and a two-choice attraction assay. Also, clary sage oil showed a significant repellent effect against D. suzukii larvae. Next, we explored the chemical constituents of clary sage oil by GC-MS and identified two major constituents, linalyl acetate (40.03%) and linalool (23.02%). Furthermore, the behavioral assays of linalyl acetate and linalool showed that both compounds conferred comparable repellency against D. suzukii adults and larvae. Finally, we found clary sage oil, linalyl acetate, and linalool elicited EAG responses in D. suzukii, especially clary sage oil, suggesting the repellency was mediated by the olfactory system. These findings indicate that D. suzukii shows olfactory-based behavioral avoidance of clary sage oil, linalyl acetate, and linalool. Clary sage oil and its major constituents may be possible alternatives in the management of D. suzukii.

CRISPR/Cas9-mediated knockout of the abdominal-B homeotic gene in the global pest, fall armyworm (Spodoptera frugiperda).

The Homeotic complex (Hox) genes play a crucial role in determining segment identity and appendage morphology in bilaterian animals along the antero-posterior axis. Recent studies have expanded to agricultural pests such as fall armyworm (FAW), scientifically known as Spodoptera frugiperda J. E. Smith (Lepidoptera: Noctuidae), which significantly threatens global agricultural productivity. However, the specific role of the hox gene Sfabd-B in FAW remains unexplored. This research investigates the spatial and temporal expression patterns of Sfabd-B in various tissues at different developmental stages using quantitative real-time polymerase chain reaction (qRT-PCR). Additionally, we explored the potential function of the Sfabd-B gene located in the FAW genome using CRISPR/Cas9 technology. The larval mutant phenotypes can be classified into three subgroups as compared with wild-type individuals, that is, an excess of pedis in the posterior abdomen, deficient pedis due to segmental fusion and deviations in the posterior abdominal segments. Importantly, significant differences in mutant phenotypes between male and female individuals were also evident during the pupal and adult phases. Notably, both the decapentaplegic (dpp) and cuticular protein 12 (cp 12) genes displayed a substantial marked decrease in expression levels in the copulatory organ of male mutants and the ovipositor of female mutants compared with the wild type. These findings highlight the importance of Sfabd-B in genital tract patterning, providing a potential target for improving genetic control.

Performance Analysis of YOLO and Detectron2 Models for Detecting Corn and Soybean Pests Employing Customized Dataset

One of the most challenging aspects of agricultural pest control is accurate detection of insects in crops. Inadequate control measures for insect pests can seriously impact the production of corn and soybean plantations. In recent years, artificial intelligence (AI) algorithms have been extensively used for detecting insect pests in the field. In this line of research, this paper introduces a method to detect four key insect species that are predominant in Brazilian agriculture. Our model relies on computer vision techniques, including You Only Look Once (YOLO) and Detectron2, and adapts them to lightweight formats—TensorFlow Lite (TFLite) and Open Neural Network Exchange (ONNX)—for resource-constrained devices. Our method leverages two datasets: a comprehensive one and a smaller sample for comparison purposes. With this setup, the authors aimed at using these two datasets to evaluate the performance of the computer vision models and subsequently convert the best-performing models into TFLite and ONNX formats, facilitating their deployment on edge devices. The results are promising. Even in the worst-case scenario, where the ONNX model with the reduced dataset was compared to the YOLOv9-gelan model with the full dataset, the precision reached 87.3%, and the accuracy achieved was 95.0%.

Development and Validation of a Novel Method Using QuEChERS and UHPLC-MS-MS for the Determination of Multiple Emerging Fungicides in Surface Waters

The increasing global reliance on pesticides for agricultural pest control has raised significant environmental concerns, particularly due to inadequate monitoring of emerging chemicals in surface waters. This study addresses the potential contamination of aquatic ecosystems by developing and validating a method for detecting trace amounts of four recently registered fungicides: three succinate dehydrogenase inhibitors (fluopyram, penthiopyrad, pydiflumetofen) and fluopicolide, a structurally related fungicide. Employing QuEChERS-based sample extraction combined with ultra-high-performance liquid chromatography (UHPLC-MS-MS), this method achieves detection limits of 0.1 to 0.2 μg/L, with recovery rates between 90% and 110%, and intra-day relative standard deviation values well within the acceptable range of less than 20%. Applied to surface grab water samples from the greater Melbourne area, Australia, the method successfully identified all four fungicides at trace levels, including a notable high concentration of fluopyram (7.3 μg/L) during autumn, with the others intermittently detected at lower concentrations. This study represents the first documented instance of quantifiable detections of these four fungicides in Australian surface water systems. Given their high toxicity to several organisms and the limited global data on these substances, our findings underscore the critical need for continuous monitoring to inform strategies to safeguard aquatic ecosystems from these chemicals.

Genetic diversity, essential oil's chemical constituents of aromatic plant Mesosphaerum suaveolens (L.) Kuntze Syn. Hyptis suaveolens (L.) Poit. and its uses in crop protection: a review.

This review provides evidence on the genetic diversity, chemical constituents, and ecotoxicology of Mesosphaerum suaveolens ' essential oil. It emphasizes the agricultural benefits such as crop protection effectiveness of the plant and highlights the existing knowledge gaps and research perspectives to promote its utilization in agriculture. A systematic and extensive review of the literature was done and all pertinent full-text articles and abstracts were analyzed and incorporated into the review. Mesosphaerum suaveolens is used traditionally in pharmacology to treat several diseases such as malaria, constipation, stomach problems, and renal inflammation. It also treats cramps, digestive infections, headaches, and skin infections. To date, very few studies have been conducted worldwide about its genetic diversity. These studies highlighted three morphological variants, the blue-flowering, the white-flowering, and the light-purple flowering M. suaveolens. Its wide biological actions may be attributed to the numerous groups of chemical constituents in its essential oil including monoterpenes, sesquiterpenes, and diterpenes. Biological studies highlighted evidence of M. suaveolens being used as an antifungal, bactericidal, antimicrobial, insecticidal, and repellent plant. The essential oil extracted from M. suaveolens showed significant potential for the control of agricultural pests such as Sitiophilus zeamais, Helicoverpa armigera and Helminthosporium oryzae. M. suaveolens is commonly used worldwide as a pesticidal plant in healthcare, agriculture, and food preservation. However, there is a lack of studies concerning the toxicity and effectiveness of isolated potent phytotoxic substances, the efficacy screening in the field, the genetic diversity, the essential oil yield, and productivity. Consequently, further studies are required to fill the knowledge gaps.

Efficacy of arginine kinase as a promising RNAi target in Aphis gossypii genome as revealed through aphid bioassay on field-grown transgenic cotton plants

The cotton aphid Aphis gossypii is a major agricultural pest of cotton that causes substantial damage to the crop not only by sucking sap but also through virus transmission. Globally adopted traditional and contemporary approaches to control aphid infestation have certain limitations and are hazardous to human health. RNA interference (RNAi) technology has unfolded its potential as an effective crop protection strategy against various pests. In this study, we adopted plant-mediated RNAi strategy to enhance aphid resistance in cotton by targeting arginine kinase (AK), which is a crucial enzyme responsible for energy homeostasis in insects. We selected a 312bp dsRNA fragment containing eight siRNAs and showing optimum GC content, Hb index, and stable secondary structure based on computational prediction studies. The binary construct expressing dsRNA was used to transform local cotton variety MNH886 and four transgenic lines were obtained in the T1 generation. Out of the four T1 transgenic cotton lines, dsA-7 exhibited the highest aphid mortality (73.3%), whereas, dsA-1, dsA-3 and dsA-6 revealed 60%, 61%, and 66.6% aphid mortality, respectively, in comparison to 13.3% mortality in the mock control cotton line. Moreover, significant knockdown in mRNA expression of AK was observed in aphids fed dsA-7 which was 79%. In comparison, 54%, 47%, and 45% downregulation was recorded in aphids which fed on dsA-6, dsA-3, and dsA-1 transgenic cotton lines, respectively. These results revealed that plant-mediated downregulation of aphid RNA induced significant RNA interference in A. gossypii which resulted in considerable aphid mortality and led to plant protection against aphids.

Efficient CRISPR/Cas9-mediated genome editing in the European corn borer, Ostrinia nubilalis.

The European corn borer (Ostrinia nubilalis) is an agricultural pest and burgeoning model for research on speciation, seasonal adaptation and insect resistance management. Although previous work in O. nubilalis has identified genes associated with differences in life cycle, reproduction, and resistance to Bt toxins, the general lack of a robust gene-editing protocol for O. nubilalis has been a barrier to functional validation of candidate genes. Here, we demonstrate an efficient and practical methodology for heritable gene mutagenesis in O. nubilalis using the CRISPR/Cas9 genome editing system. Precise loss-of-function (LOF) mutations were generated at two circadian clock genes, period (per) and pigment-dispersing factor receptor (pdfr), and a developmental gene, prothoracicotropic hormone (ptth). Precluding the need for a visible genetic marker, gene-editing efficiency remained high across different single guide RNAs (sgRNA) and germline transmission of mutations to F1 offspring approached 100%. When single or dual sgRNAs were injected at a high concentration, gene-specific phenotypic differences in behaviour and development were identified in F0 mutants. Specifically, F0 gene mutants demonstrated that PER, but not PDFR, is essential for normal timing of eclosion. PTTH F0 mutants were significantly heavier and exhibited a higher incidence of diapause. This work will accelerate future studies of gene function in O. nubilalis and facilitate the development of similar screens in other Lepidopteran and non-model insects.

Genome sequence of the sugarcane aphid, Melanaphis sacchari (Hemiptera: Aphididae).

The sugarcane aphid, Melanaphis sacchari (Zehntner, 1897), is an agricultural pest that causes damage to plants in the Poaceae (the grasses) family, such as sorghum and sugarcane. Here, we used Nanopore long reads and Hi-C interaction map to generate a chromosome-level assembly with a total length of 356.1 Mb, of which 85.5% (304.6 Mb) is contained within the three autosomes and the X chromosome. Repetitive sequences accounted for 16.29% of the chromosomes and a total of 12,530 protein-coding genes were annotated, achieving 95.8% benchmarking universal single-copy orthologs (BUSCO) gene completeness. This offers a substantial improvement compared to previous low-quality genomic resources. Phylogenomic analysis by comparing M. sacchari with twenty-four published aphid genomes representing three aphid tribes reveals that M. sacchari belongs to the tribe Aphidini and maintained a conserved chromosome structure with other Aphidini species. The high-quality genomic resources reported in this study will be useful for understanding the evolution of aphid genomes and studying pest management of M. sacchari.

Perception of Farmers towards M-Kisan Initiative

India is an agrarian country and risk and uncertainties are omnipresent in the field of agriculture. The farmer’s exposure to risk and uncertainty is often provoked by lack of information about required inputs and crop management practices etc. This information gap has adverse impact on production as well as the income of farmers. As use of ICT has strongly influenced every socio-economic aspect to become the most significant motivation of the socio-economic development and poverty reduction, Government of India launched m-Kisan portal to deliver updated information to the farmers through SMS. It is an initiative by the Indian government to provide agricultural services and information to farmers through mobile phones. The mKisan platform allows farmers to receive updates on agricultural practices, weather forecasts, market prices, pest control, and other farming-related advice via SMS, voice messages, and mobile apps. The present study tries to identify the utility perception of the m-kisan users. Data were collected from 120 respondents, from four villages of three different talukas of Bhavnagar district through personal interview schedule during 2022 and then after data were compiled, tabulated and analysed to get proper answer for the specific objectives of the study. Slightly more than half (51.67%) of the respondents had medium utility perception.

Impact of camptothecin exposures on the development and larval midgut metabolomic profiles of Spodoptera frugiperda

Spodoptera frugiperda is an economic agricultural pest that has invaded many countries around the world and caused huge losses in grain production. Camptothecin (CPT) is one of the botanical compounds with insecticidal activity and has the potential for pest control. However, the effects of CPT on development and metabolism of S. frugiperda remain unknown. In this study, we have investigated the adverse effects of 1.0 and 5.0 mg/kg CPT exposures on the growth and development of S. frugiperda. Our results found that 1.0 and 5.0 mg/kg CPT treatments altered the parameters of the life cycle, including inducing larval mortality, altering the weight of larvae, pupae, and adults, the larval duration, and decreasing the pupation rate and emergence rate. In addition, comparative metabolomics analysis was performed in the larval midgut of S. frugiperda to explore the toxicity mechanism of CPT. A total of 261 and 348 differential metabolites were identified in the groups with 1.0 and 5.0 mg/kg CPT treatments, respectively. Further analysis found that pantothenate and CoA biosynthesis, sulfur relay system, selenocompound metabolism, and fatty acid biosynthesis pathways were significantly altered by 5.0 mg/kg CPT exposure. Our results provided new insight into the toxicological mechanisms of CPT against S. frugiperda and laid the foundation for the field application of CPT in pest control.

Optimized nanopesticide delivery of thiamethoxam to cowpeas (Vigna unguiculata) controls thrips (Megalurothrips usitatus) and reduces toxicity to non-target worker bees (Apis mellifera)

Thrips [Megalurothrips usitatus (Bagnall)] (Thysanoptera: Thripidae) is a pest that poses a serious challenge to global crop production and food supply, especially to the cowpea industry. Nano-delivery systems have broad application prospects in the prevention and control of pests in agriculture. Herein, three types of amino acid (AA) modified polysuccinimide nano-delivery carriers (PSI-GABA, PSI-ASP and PSI-GLU) were constructed with a diameter of approximately 150 nm to load thiamethoxam (THX), which enhanced THX effective distribution and use with cowpea plants. Significantly, the PSI-GLU nanocarrier effectively delivered THX to cowpea plant tissues following 6 h of soil application. Compared with commercial THX suspension (SC), the THX content in the leaves of cowpea plants was increased by 2.3 times. Confocal laser scanning microscopy revealed that the FITC-labeled PSI-GLU nanocarrier reached the leaves through the vascular system after being absorbed by the roots of cowpea plants. The PSI-GLU nanocarrier decreased the LC50 of THX from 11.45 to 7.79 mg/L and significantly enhanced the insecticidal effect. The PSI-GLU nanocarrier also improved the safety of THX to worker bees at 48 h, and moreover showed a growth-promoting effect on cowpea seedlings. These results demonstrated that the PSI-GLU nano-delivery carrier has promising uses on improving the effective utilization of THX for the sustainable control of thrips and reducing the risk to non-target pollutions.

Identification and biophysical characterization of potential phytochemical inhibitors of carboxyl/choline esterase from Helicoverpa armigera for advancing integrated pest management strategies

In the realm of disease vectors and agricultural pest management, insecticides play a crucial role in preserving global health and ensuring food security. The pervasive use, particularly of organophosphates (OPs), has given rise to a substantial challenge in the form of insecticide resistance. Carboxylesterases emerge as key contributors to OP resistance, owing to their ability to sequester or hydrolyze these chemicals. Consequently, carboxylesterase enzymes become attractive targets for the development of novel insecticides. Inhibiting these enzymes holds the potential to restore the efficacy of OPs against which resistance has developed. This study aimed to screen the FooDB library to identify potent inhibitory compounds targeting carboxylesterase, Ha006a from the agricultural pest Helicoverpa armigera. The ultimate objective is to develop effective interventions for pest control. The compounds with the highest scores underwent evaluation through docking studies and pharmacophore analysis. Among them, four phytochemicals—donepezil, protopine, 3′,4′,5,7-tetramethoxyflavone, and piperine—demonstrated favorable binding affinity. The Ha006a-ligand complexes were subsequently validated through molecular dynamics simulations. Biochemical analysis, encompassing determination of IC50 values, complemented by analysis of thermostability through Differential Scanning Calorimetry and interaction kinetics through Isothermal Titration Calorimetry was conducted. This study comprehensively characterizes Ha006a-ligand complexes through bioinformatics, biochemical, and biophysical methods. This investigation highlights 3′,4′,5,7-tetramethoxyflavone as the most effective inhibitor, suggesting its potential for synergistic testing with OPs. Consequently, these inhibitors offer a promising solution to OP resistance and address environmental concerns associated with excessive insecticide usage, enabling a significant reduction in their overuse.

Genome-wide analysis of the WRKY family in Nicotiana benthamiana reveals key members regulating lignin synthesis and Bemisia tabaci resistance

WRKY transcription factors (TFs) play a pivotal role in plant resistance against stress. Lignin is a plant component that is of great importance in many industrial and agricultural disciplines. However, how WRKYs regulate plant lignin synthesis pathways and defense against insects is largely unknown. Here, we investigate WRKYs in Nicotiana benthamiana, a model plant and biofactory widely used worldwide, elucidating their responses to the Bemisia tabaci whitefly, a globally significant agricultural pest, and their functions in regulating plant defense by regulating lignin synthesis. Firstly, we identified a total of 118 NbWRKYs in the N. benthamiana genome and performed necessary bioinformatics analyses. Then, we studied nine whitefly-inducible NbWRKYs and found that they were localized in the nucleus, significantly expressed in leaf tissues, and affected the phytohormone pathways. Meanwhile, NbWRKY21, NbWRKY45, NbWRKY81, and NbWRKY117 were proved to be involved in defense against whiteflies. Additionally, through DNA-TFs interaction experiments, we demonstrated that the WRKYs activated the expression of key genes—Cinnamate-4-hydroxymate (C4H), 4-coumarate-CoA ligase (4CL), and Cinnamoyl-CoA reductase (CCR)—in the lignin synthesis pathway. Specifically, NbWRKY81 activated the NbC4H and Nb4CL, while NbWRKY45 promoted NbCCR, by binding to their promoters, affecting whitefly feeding behavior, and therefore enhancing whitefly defense. Our findings contribute to a comprehensive knowledge of the WRKYs in plant defense against herbivore insects by regulating lignin synthesis.

Novel Pesticide Candidates Inspired by Natural Neolignan: Preparation and Insecticidal Investigation of Honokiol Analogs Containing 2-Aminobenzoxazole-Fused Core Scaffold.

As a continuation of our efforts to develop new agrochemicals with typical architecture and efficient bioactivity from plant natural products, natural neolignan honokiol was used as a lead compound to prepare novel analogs bearing the core 2-aminobenzoxazole scaffold. Their insecticidal potency against two representative agricultural pests, Plutella xylostella Linnaeus and Mythimna separata (Walker), were evaluated in vivo. The pesticide bioassay results revealed that compounds 7″a, 9, 10d, and 10j exhibited prominent larvicidal activity against the larvae of P. xylostella (LC50 = 7.95, 11.85, 15.51, and 12.06 μg/mL, respectively), superior to the precursor honokiol (LC50 = 43.35 μg/mL) and two botanical insecticides, toosendanin (LC50 = 26.20 μg/mL) and rotenone (LC50 = 23.65 μg/mL). Compounds 7d, 10d, and 10j displayed a more pronounced nonchoice antifeedant effect (AFC50 = 9.48, 9.14, and 12.41 μg/mL, respectively) than honokiol (AFC50 = 54.81 μg/mL) on P. xylostella. Moreover, compounds 7b, 7″a, 9, 10d, 10f, and 10j showed better growth inhibitory activity against M. separata (LC50 = 0.36, 0.34, 0.28, 0.16, 0.26, and 0.11 mg/mL, respectively) than honokiol, toosendanin, and rotenone (LC50 = 1.48, 0.53, and 0.46 mg/mL, respectively). A potted plant assay under greenhouse conditions illustrated that compounds 10d and 10j continued to provide good control efficacy against P. xylostella and an apparent protective effect on plants. Further cytotoxicity assay revealed that the aforementioned potent compounds showed relatively moderate toxicity and a good safety profile for non-target mammalian cells. Overall, the current work provides valuable insight into the agrochemical innovation of honokiol-derived analogs for use as natural-inspired pesticides in agricultural pest management.

Warmer environmental temperature accelerates aging in mosquitoes, decreasing longevity and worsening infection outcomes

BackgroundMost insects are poikilotherms and ectotherms, so their body temperature is predicated by environmental temperature. With climate change, insect body temperature is rising, which affects how insects develop, survive, and respond to infection. Aging also affects insect physiology by deteriorating body condition and weakening immune proficiency via senescence. Aging is usually considered in terms of time, or chronological age, but it can also be conceptualized in terms of body function, or physiological age. We hypothesized that warmer temperature decouples chronological and physiological age in insects by accelerating senescence. To investigate this, we reared the African malaria mosquito, Anopheles gambiae, at 27 °C, 30 °C and 32 °C, and measured survival starting at 1-, 5-, 10- and 15-days of adulthood after no manipulation, injury, or a hemocoelic infection with Escherichia coli or Micrococcus luteus. Then, we measured the intensity of an E. coli infection to determine how the interaction between environmental temperature and aging shapes a mosquito’s response to infection.ResultsWe demonstrate that longevity declines when a mosquito is infected with bacteria, mosquitoes have shorter lifespans when the temperature is warmer, older mosquitoes are more likely to die, and warmer temperature marginally accelerates the aging-dependent decline in survival. Furthermore, we discovered that E. coli infection intensity increases when the temperature is warmer and with aging, and that warmer temperature accelerates the aging-dependent increase in infection intensity. Finally, we uncovered that warmer temperature affects both bacterial and mosquito physiology.ConclusionsWarmer environmental temperature accelerates aging in mosquitoes, negatively affecting both longevity and infection outcomes. These findings have implications for how insects will serve as pollinators, agricultural pests, and disease vectors in our warming world.

Predicting possible distribution of rice leaf roller (Cnaphalocrocis medinalis) under climate change scenarios using MaxEnt model in China

The relationship between climate conditions and pest life is a key determinant of their distribution. Cnaphalocrocis medinalis Guenee, a major rice pest, exhibits outbreaks and its distribution patterns closely linked to meteorological factors. By using 244 actual distribution and occurrence data of C. medinalis along with 8 bioclimatic data, and employing the MaxEnt model and ArcGIS, combined with the latest SSPs climate scenario data, this study evaluated the risk region distribution status in the current period and predicted changes in China from 2040 to 2100. The results indicate that an overall increase in the risk area for C. medinalis, particularly under SSP245 scenario during 2040–2060. While Low-risk areas are expected to decrease, Medium and High-risk areas are projected to increase significantly, with worsening pest infestations anticipated in southern Hubei, eastern Hunan, most of Jiangxi, central Fujian, northern Guangdong, and southern Jiangsu. Regions such as central Liaoning are expected to reach the minimum survival standard for C. medinalis in future, leading to the northward shift in risk areas. Difference plots highlighted areas of increased and decreased suitability, providing actionable insights for policymakers. Regions with increased suitability align with the predicted northward shift of many agricultural pests, necessitating enhanced monitoring, specific pest control measures, and updated agricultural policies to address changing risk profiles. Additionally, the centroid analysis showed a northwest shift direction in future, primarily located at the junction of Shaoyang City and Loudi City, situated around 27–28 °N degrees north latitude and 111–113 °E. The study underscores the significant impact of climate change on the distribution of rice leaf roller, providing valuable insights for agricultural planning and management. The northward and westward expansion of risk areas necessitates adaptive strategies to mitigate potential impacts on agriculture. Enhanced monitoring, integrated pest management, and the development of pest-resistant crops are essential for addressing future challenges posed by climate change.