Spodoptera Frugiperda Research Articles

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.

Impact of phenology, brown midrib (BMR), seed treatment, and herbivory on epicuticular wax content and fall armyworm (Spodoptera frugiperda) feeding in sorghum-sudangrass (Sorghum xdrummondii)

In crop production, management strategies have historically relied upon chemical control to mitigate insect pest pressures. As resistance to pesticides grows at an alarming rate, and as non-target effects are found more frequently, the search for sustainable, novel pest management strategies has become more important. Plants are equipped with diverse physical and chemical defenses against insect pests. Among these physical defenses, epicuticular waxes serve as an important first line of defense. Yet, how these chemical control methods such as seed treatment affects epicuticular waxes is underexplored. Brown midrib (BMR) is a host-plant trait from a recessive gene that affects the monolignol biosynthetic pathway, reducing lignin content, and presents as a gene of interest for evaluation as a form of pest management. Sorghum-sudangrass, Sorghum x drummondii, is an economically important forage crop with BMR; however, the effects of BMR have primarily been studied in animal agriculture and its effects on insects is largely unknown. In addition, how BMR affects epicuticular waxes is also unknown. This study aims to understand how the quantity of epicuticular wax in Sorghum x drummondii is affected by chemical control (seed treatments), BMR, phenological stages, and how wax affects a polyphagous, destructive pest, fall armyworm, Spodoptera frugiperda (FAW). Through wax quantification and FAW feeding induction and wax added artificial diet experiments, we show that while BMR and seed treatment does not affect wax content, plant phenology affects wax, and wax is induced by FAW feeding and has negative consequences for caterpillar growth.

Fall Armyworm Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae) in East Nusa Tenggara Province of Indonesia: Genetic Characterization and Strain Detection

<em>Spodoptera frugiperda</em> J.E. Smith (Lepidoptera: Noctuidae) is an invasive pest of corn plants spreading throughout the world, including East Nusa Tenggara (NTT), Indonesia. Despite the wide distribution, there is a lack of information on the strain or genetic diversity of the pest in NTT. Therefore, this study aimed to determine the strain of <em>S. frugiperda</em> from several areas in NTT with a molecular method using <em>cytochrome oxidase subunit 1</em> (<em>COI</em>)<em> </em>and <em>triose phosphate isomerase</em> (<em>Tpi</em>)<em> </em>gene markers. The<em> </em>samples were collected from 3 islands: Timor, Flores, and Sumba. Amplification of the marker genes was carried out using 3 specific primers to identify the strain obtained from samples. Subsequently, polymerase chain reaction (PCR) products were sequenced and the DNA sequences were analyzed using the BioEdit and BLAST programs. Phylogeny analyses were carried out using the MEGA 11 program to verify the strain group of samples with reference isolates from other countries found in GenBank. The PCR results showed product amplicon size 811 bp for the <em>CO1A</em> marker. Based on phylogeny tree analysis using <em>COI </em>marker, <em>S. frugiperda </em>from NTT showed 2 clades, namely corn and rice strains. The characterization results showed that <em>S. frugiperda</em> in NTT comprised 63.6% corn and 36.4% rice strains. <em>COIB </em>classified <em>S. frugiperda</em> from NTT into the h4 haplotype subgroup, while <em>Tpi </em>gene marker was in the corn strain. This study provided valuable information regarding the strain of <em>S. frugiperda</em> in Indonesia to determine the appropriate control strategy.

Multigenerational hormetic effects of different insecticides on Spodoptera frugiperda (J.E. smith) (Lepidoptera: Noctuidae)

To protect crops from pest insects, farmers continuously use insecticides, which eventually degrade into residue due to abiotic or biotic factors. These residual effects of pesticides may cause low lethal and/or sublethal impacts on the exposed pest insect populations, leading to the induction of pest resurgence through hormesis and ultimately the development of resistance. Hormesis is a beneficial bi-phasic effect generally characterized by low-dose reproductive stimulation and high-dose inhibition. In the present study, we investigated the impact of low lethal and sublethal concentrations (LC10, LC20, and LC30) of spinetoram, chlorantraniliprole, and thiodicarb on the F0 generation as well as their multigenerational hormesis effects on the F1 and F2 generations of Fall Armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae). The study focused on reproductive parameters, fecundity, fertility, and life index parameters such as net reproductive rate (R0), intrinsic rate of increase (rm), finite rate of increase (λ), mean length of generation (Tc), and gross reproductive rate (GRR). Fecundity of S. frugiperda increased by 4.82%, 4.63% and 4.58%, while eggs fertility improved by 7.77%, 6.78% and 6.52% at LC10 of thiodicarb, chlorantraniliprole and spinetoram, respectively, from the F1 to F2 generation. Further, interaction analysis (Concentration × Insecticidal treatments) revealed that important vital parameters like pre-oviposition period (POP), oviposition period (OP), post-oviposition period (PtOP), R0,rm,λ, Tc and GRR of F0 were negatively impacted by LC30 of all the tested insecticides and LC20 of only spinetoram. However, LC10 of any of the tested insecticides did not affect these parameters when compared with control. Furthermore, interactive analysis in multigenerational exposure experiments (Concentration × Insecticidal treatments × Generation(s)) showed hermetic effects of LC10 of all tested insecticides which is more positive in F2 as compared to F1 generation. These unwanted positive hermetic effects of low lethal concentrations (LC10) of tested insecticides in offspring of exposed parental population of S. frugiperda indicated its resistance and/or resurgence. Furthernore, present study emphasizes the necessity for additional research to elucidate the underlying mechanisms responsible for these effects.

Sublethal Effects on the Biological Development of Spodoptera frugiperda (Lepidoptera: Noctuidae) When Consuming Neem

Objective: The Fall armyworm S. frugiperda was bred in laboratory and put under dose of watery extracts andoil of seed of A. indica with the aim of determining and to quantify the alterations in the biological developmentof larvae and pupae of caused by the consumption of A. indica and the doses in which the alterations happen.Design/Methodology/Approach: Two experiments were development. In one eight doses were evaluated,with watery extract of seed of A. indica in 4.0, 1.0, 0.7, 0.4, 0.1, 0.07, 0.04 and 0.01%. In the second the doses ofoil of A. indica were evaluated 0.16, 0.09, 0.02, 0.016, 0.009, 0.002, 0.0016 and 0.0009%. In both experimentsthe variables were quantified: duration of the stage of larvae and pupae, survival of the larval stage and pupae,survival of the larva stage and pupae and weight of pupae.Results: The larvae prolonged their development in three days more than the witness when consuming wateryextract of A. indica; They reduced its survival like la rvae and pupa in 18 and 27.5% respectively. In Addition,was reduced the weight of pupas. When consuming oil of A. indica, the larvae delayed their development fromthree to 15 and 19 days more than the witness.Study limitations/Implications: The study was carried out under laboratory conditions and in a single cycle;it is desirable to repeat the study for more cycles and with different populations of fall armyworm.Finding/Conclusions: The adverse effects in larvae were pronounced of three forms: 1) the duration of thelarval stage altered when staying the larvae by more days in that stage without changing pupae. 2) the survivalof the larval stage was reduced and 3) it decreased weight of pupa.

Host Species Affects Gut Microbial Community and Offspring Developmental Performances in the Pupal Parasitoid Chouioia cunea Yang (Hymenoptera: Eulophidae).

Chouioia cunea are known to exploit in varying degrees a wide range of lepidopteran species and its offspring development may vary with host species. This study examined its preimaginal development and larval gut microbiota in parasitizing five folivorous lepidopteran hosts including Hyphantria cunea (referred to thereafter as CcHc), Antherea pernyi (CcAp), Helicoverpa armigera (CcHa), Spodoptera exigua (CcSe), and Spodoptera frugiperda (CcSf). Though rates of parasitism and offspring eclosion did not change with host species, the development period and number of offspring eclosed varied with hosts, with the shortest period in CcSf and the highest number from CcAp. For offspring larval gut microbiota, though phylum Proteobacteria was dominant for attacking CcAp, Firmicutes was so for the other hosts. All microbial genera except Enterococcus were less abundant for CcSf than the other hosts. The database-based predictions indicate a significant positive correlation between Cutibacterium and Aureimonas with the relative number of wasp emergence, while Blastomonas exhibits a strong positive association with the developmental period. Our results imply the potential relevance of the gut microbial community in offspring larvae to host species attacked by C. cunea.

Weather Influence on Fall Armyworm Infestation in Maize: A Study in Perambalur District, Tamil Nadu, India

Maize, Zea mays L (Family: Poaceae), is a main cereal crop cultivated across diverse agro-climatic regions worldwide. The Fall Armyworm (FAW), Spodopterafrugiperda (J. E. Smith) (Lepidoptera: Noctuidae), migratory insect is notorious for its economic impact, inflicting severe damage on various crops including maize, rice, sorghum, millet, sugarcane, vegetables, and cotton, and has been documented to affect over 80 other plant species. A roving survey was carried out in four major maize growing blocks of Perambalur district viz., Perambalur, Veppanthattai, Alathur and Veppur during Kharif and Rabi season of 2023-2024. The experiment consisted of sixty standard weeks from 3rd July 2023 to 4th August 2024. The results indicated a positive correlation between the number of fall armyworm larvae/plant with Tmax, relative humidity (Evening), and the negative correlation was observed between the number of fall armyworm larvae/plant with Tmin, relative humidity (Morning), Sunshine and rainfall. The data concluded that the maximum temperature significantly influenced the emergence of the fall armyworm and its infestation on maize. The incidence of FAW started in 46th mean standard week MSW (13 larvae/plant) Alathur, (17.25 larvae/plant) Perambalur, (17.25 larvae/plant) Veppanthattai, (18 larvae/plant) Veppur and the population increased gradually and reached the peak in the 47th mean standard week MSW (26 larvae/plant) Alathur, (32.75 larvae/plant) Perambalur, (33 larvae/plant) Veppanthattai, (42 larvae/plant). Correlation analysis revealed that larval population showed a significant positive correlation with the maximum temperature and relative humidity. At the same time, minimum temperature, sunshine, and rainfall exhibited a negative association with larval incidence of S. frugiperda. Propose adaptation strategies for maize farmers in Perambalur to manage fall armyworm infestations in the context of changing weather patterns. This could include adjustments in planting dates, pest monitoring techniques, or integrated pest management approaches.

Evolutionary Systems Biology Identifies Genetic Trade-offs In Rice Defense Against Above- and Belowground Attackers.

Like other plants, wild and domesticated rice species (Oryza nivara, O. rufipogon, and O. sativa) evolve in environments with various biotic and abiotic stresses that fluctuate in intensity through space and time. Microbial pathogens and invertebrate herbivores such as plant-parasitic nematodes and caterpillars show geographical and temporal variation in activity patterns and may respond differently to certain plant defensive mechanisms. As such, plant interactions with multiple community members may result in conflicting selection pressures on genetic polymorphisms. Here, through assays with different above- and belowground herbivores, the fall armyworm (Spodoptera frugiperda) and the southern root-knot nematode (Meloidogyne incognita), respectively, and comparison with rice responses to microbial pathogens, we identify potential genetic trade-offs at the KSL8 and MG1 loci on chromosome 11. KSL8 encodes the first committed step towards biosynthesis of either stemarane- or stemodane-type diterpenoids through the japonica (KSL8-jap) or indica (KSL8-ind) allele. Knocking out KSL8-jap and CPS4, encoding an enzyme that acts upstream in diterpenoid synthesis, in japonica rice cultivars increased resistance to S. frugiperda and decreased resistance to M. incognita. Furthermore, MG1 resides in a haplotype that provided resistance to M. incognita, while alternative haplotypes are involved in mediating resistance to the rice blast fungus Magnaporthe oryzae and other pests and pathogens. Finally, KSL8 and MG1 alleles are located within trans-species haplotypes and may be evolving under long-term balancing selection. Our data are consistent with a hypothesis that polymorphisms at KSL8 and MG1 may be maintained through complex and diffuse community interactions.

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.

Evaluation of the Maize - False basil Cultural Association in the Fight against the Fall Armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae)

In Ivory Coast, maize (Zea mays L.) is the second most cultivated cereal after rice. Despite this, maize cultivation is limited by pest pressures. Apart from the usual pests, a new enemy has arrived on the continent, the fall armyworm, Spodoptera frugiperda. To control this pest, farmers use pesticides, which are not only expensive, but also pose risks to human health and the environment. The objective of this study is to find an alternative solution to chemical control through the cultivation of maize-Ocimum gratissimum (False basil) in two ways. The first consisted in planting False basil around the maize plot as a barrier plant (P1). The second consisted of alternating maize plants with False basil plants (P2). The experimental design used was a one-factor randomized FISHER block with three treatments. The efficacy of the two association modalities was compared to that of control which was maize crop only. The results showed better control of fall armyworm in the combination than control. Of the two combination treatments, it was the P1 treatment that was effective against S. frugiperda compared to the P2 treatment and the control. Thus the infestation rate of treatment P1 (33 %) was lower than that of treatment P2 (50 %) followed by the control (70 %). In addition, it was the P1 treatment that harbored fewer armyworms (8 larvae) compared to the P2 treatment (22 larvae) and the control (35 larvae). The maize-False basil crop combination therefore appears to be beneficial than pure crops as it significantly reduces the infestation rate, damage level and harbors less fall armyworm population.

Bioactive Insecticides from Chemometric Diverse Ant-Associated Symbionts Streptomyces novaecaesareae and Streptomyces nojiriensis against the Fall Armyworm Larvae.

The Streptomyces genus has long been recognized as a prolific and valuable source of diverse secondary metabolites. These metabolites contribute significantly to the intricate chemical diversity exhibited by Streptomyces, making them an indispensable reservoir for drug discovery, agricultural applications, and industrial processes. Exploiting the potential of these natural compounds holds the promise of ushering in a new era in insect pest management, reducing reliance on synthetic chemicals and fostering ecologically sustainable solutions. This study dives into the realm of chemo diversity within isolates of Streptomyces nojiriensis and Streptomyces novaecaesareae, with a specific focus on the production of insecticidal compounds. We explored chromatographic techniques for the identification and isolation of insecticidal compounds, and two bioactive compounds were identified in extracts of S. novaecaesareae. Valinomycin was identified from hexanic extracts of strain Asp59, while naphthomycin from ethyl acetate extracts of strain Asp58. These compounds showed insecticidal activity against first instars of Spodoptera frugiperda (Asp59: LC50 = 10.82 µg/µL, LC90 = 26.25 µg/µL; Asp58: LC50 = 15.05 µg/µL, LC90 = 38.84 µg/µL). Notably, this is the first report of naphthomycin as an insecticidal compound. The present study suggests that valinomycin and naphthomycin may be a novel biological source for the control of Spodoptera frugiperda in early stages.

Assessment of yield loss due to fall armyworm in maize using high-resolution multispectral spaceborne remote sensing

ABSTRACT The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), invasion endangered the maize production worldwide, including India. The objective of this study was to quantify the FAW damage severity and its impact on leaf area index (LAI), biomass and grain yield of maize and to detect the field damage using high-resolution multispectral spaceborne remote sensing data. Maize growing fields in the Kurnool District of Andhra Pradesh and the Gadwal District of Telangana, India, were randomly surveyed to collect detailed ground-truth information. Foliar damage due to FAW was recorded, and the fields were categorized into various severity grades (healthy, low, medium and severe). FAW infestation caused significant change in LAI between the severity grades, which formed the basis for its damage detection using multispectral spaceborne remote sensing. Severe FAW infestation caused significant reduction in LAI, biomass and grain yield ranging between 36.9 and 39.9% compared to healthy grade. The infestation at the leaf collar (LC) stage caused significant yield loss of up to 26.5% compared to the tassel initiation (TI) and tasselling and silking (TS) stages. Canopy spectral reflectance from healthy and FAW-infested plants showed significant differences in the visible and near infrared (NIR) regions. A reflectance peak was observed in the NIR region of healthy plants compared to infested plants. Among various spaceborne vegetation indices, the Soil Adjusted Vegetation Index (SAVI) performed better in identifying the FAW infestation (R2 = 0.61**), biomass (R2 = 0.70**) and yield loss (R2 = 0.82**). These findings indicate the feasibility of utilizing multispectral remote sensing data for monitoring FAW infestation on a spatial scale, thus enabling the site-specific management.

Efficacy of Newer Insecticides against Fall Armyworm, Spodoptera frugiperda on Maize

The effectiveness of various newer insecticides against fall armyworm was assessed. The different treatments were spray viz., flubendiamide 39.35 % SC, chlorantraniliprole 18.5% SC, emamectin benzoate 5% SG, Beauveria bassiana, Metarhizium anisopliae, neem seed kernel extract, Bacillus thuringiensis and control. The overall mean of the two sprays revealed that the most effective treatment was chlorantraniliprole 18.5% SC recorded the lowest larval population followed by emamectin benzoate 5% SG, Flubendiamide 39.35 % SC, Bacillus thuringiensis, Beauveria bassiana, Metarhizium anisopliae, neem seed kernel extract. During the yield observation, it was observed that a significantly higher yield was obtained in chlorantraniliprole 18.5% SC treated plots which is followed by emamectin benzoate 5% SG, flubendiamide 39.35 % SC, Bacillus thuringiensis, Beauveria bassiana, Metarhizium anisopliae and NSKE 5 %. Maximum percentage increase in yield over control was obtained from chlorantraniliprole 18.5% SC treated plots which are followed by emamectin benzoate 5% SG, flubendiamide 39.35 % SC, Bacillus thuringiensis, Beauveria bassiana, Metarhizium anisopliae and NSKE 5 %. The economics of various treatments based on net profit and cost of plant protection revealed that the highest cost: benefit ratio was observed in plot treated with emamectin benzoate 5% SG followed by Beauveria bassiana, chlorantraniliprole 18.5% SC, Bacillus thuringiensis, NSKE, Metarhizium anisopliae, flubendiamide 39.35 % SC.

Design, Synthesis, and Insecticidal Activity of Isoxazoline Derivatives Incorporating an Acylhydrazine Moiety.

The long-term use of agricultural insecticides has led to the development of resistant strains. In this context, the isoxazoline structure has become an active area of pesticide research owing to its wide insecticidal spectrum, nontoxicity to mammals, and lack of cross-resistance with known insecticides. In the present study, based on the discovery of compound G22 in our previous work, a series of novel isoxazoline compounds containing acylhydrazine were designed and synthesized using a scaffold hopping strategy. The insecticidal activities of the target compounds were assessed, and compound L17 (LC50 = 0.489 mg/L) showed insecticidal activity against Spodoptera frugiperda superior to those of the commercial insecticides indoxacarb (LC50 = 3.14 mg/L) and fluralaner (LC50 = 0.659 mg/L). Theoretical calculations indicated that the introduction of acylhydrazine plays an important role in the biological activity of the target compounds. Furthermore, the enzyme-linked immunosorbent assay and molecular docking results indicated that L17 may act on the GABA receptor of the target insect. These results indicated that L17 is a potential candidate compound for controlling S. frugiperda populations in agriculture.

Sublethal and transgenerational effects of chlorfenapyr on physiological and developmental traits of Spodoptera frugiperda

Sublethal and transgenerational effects of chlorfenapyr on physiological and developmental traits of Spodoptera frugiperda

Combined Metabolome and Transcriptome Analyses of Maize Leaves Reveal Global Effect of Biochar on Mechanisms Involved in Anti-Herbivory to Spodoptera frugiperda.

Fall armyworm (FAW, Spodoptera frugiperda) has now spread to more than 26 Chinese provinces. The government is working with farmers and researchers to find ways to prevent and control this pest. The use of biochar is one of the economic and environmentally friendly strategies to increase plant growth and improve pest resistance. We tested four v/v combinations of bamboo charcoal with coconut bran [BC1 (10:1), BC2(30:1), BC3(50:1)] against a control (CK) in maize. We found that plant height, stem thickness, fresh weight and chlorophyll content were significantly higher in BC2, in addition to the lowest FAW survival %. We then compared the metabolome and transcriptome profiles of BC2 and CK maize plants under FAW herbivory. Our results show that the levels of flavonoids, amino acids and derivatives, nucleotides and derivatives and most phenolic acids decreased, while terpenoids, organic acids, lipids and defense-related hormones increased in BC-grown maize leaves. Transcriptome sequencing revealed consistent expression profiles of genes enriched in these pathways. We also observed the increased expression of genes related to abscisic acid, jasmonic acid, auxin and MAPK signaling. Based on these observations, we discussed the possible pathways involved in maize against FAW herbivory. We conclude that bamboo charcoal induces anti-herbivory responses in maize leaves.

Screening the larvicidal activity of ZnO, CuO nanoparticles, and neem seed oil extract against the full armyworm Spodoptera frugiperda (J. E. Smith) (Lepidoptera, Noctuidae)

Screening the larvicidal activity of ZnO, CuO nanoparticles, and neem seed oil extract against the full armyworm Spodoptera frugiperda (J. E. Smith) (Lepidoptera, Noctuidae)

Maize yield and Fall armyworm damage responses to genotype and sowing date-associated variations in weather conditions

Due to climate disruption and delayed onset of rains, maize is often sown late, outside the optimal window, increasing the impact of pests such as fall armyworm and reducing yields. Identifying optimal sowing dates and the best genotypes is crucial to maximise yields while limiting fall armyworm (FAW) damage. Thus, this study was undertaken to evaluate yield and FAW damage variation in relation to sowing-date weather conditions to determine the optimal sowing window. The experiment had a split-plot design with four genotypes ('PVAH-1 L', 'PVAH-3 L', 'PVAH-6 L' and 'SAM 4 VITA') and four sowing dates (30 November to 14 January and delayed by 15, 30 and 45 days) during the three consecutive cropping seasons. Abundant rainfall and a high number of wet days increase yields while reducing FAW damage. The genotype shows that 'PVAH-1 L' has ear resistance (3.24) and leaf partial resistance (4.05) to FAW, with a high yield (6.54 t.ha−1). In contrast, 'PVAH-3 L' (4.27 and 5.05), 'PVAH-6 L' (4.24 and 4.37) and 'SAM 4 VITA' (4.25 and 4.00) show partial resistance to FAW in both ears and leaves, but have relatively lower yields, except for 'PVAH-6 L' (6.29 t.ha−1). Maize sown on 15 December had a high yield (8.76 t.ha−1), similar to those sown on 30 November. However, sowing on 30 December and 14 January reduced yields by 2 t.ha−1 and 7 t.ha−1 respectively, while increasing FAW infestation and damage. Therefore, in the Lubumbashi region, due to the delayed onset of rains and climatic disturbances, the sowing period can be extended to 30 December, with an optimal window extending from 30 November to 15 December. To maximise yields and limit FAW damage, it is recommended that 'PVAH-1 L' be sown on 15 December, 'SAM 4 VITA' on 30 November or 15 December and 'PVAH-6 L' on 30 November or 15 December.

Effects of Global Climate Warming on the Biological Characteristics of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae).

Spodoptera frugiperda (J.E. Smith) is a significant economic pest that has recently invaded Africa and Asia. However, much of the information regarding its ecological capabilities in these newly invaded environments remains largely unknown. In this study, the life history traits of the fall armyworm under conditions of increased temperature, different photoperiods, and varying humidity levels were systematically evaluated. Among 43 studies, a total of 20 studies were included in the analysis by passing the screening criteria, and random-effects meta-analysis, fixed-effects meta-analysis, and meta-regression were conducted. It has been found that with the increase in temperature above 20 °C, various physiological indicators of the fall armyworm are significantly enhanced. When the temperature reaches 32 °C, the physiological activities of S. frugiperda are at their highest point. As the temperature increases, the duration of each developmental stage of the fall armyworm decreases significantly, accompanied by an increase in oviposition quantity and period in females. Additionally, the pupal development time is shortened, which leads to an increase in the lifespan of the adult moth. Using temperature and relative humidity as environmental variables, the optimal survival conditions for each insect state of the fall armyworm were calculated. These findings can assist in predicting the population dynamics of the fall armyworm and in formulating appropriate and practical management strategies.

Salivary Protein Sfapyrase of Spodoptera frugiperda Stimulates Plant Defence Response.

Plants have developed various resistance mechanisms against herbivorous insects through prolonged coevolution. Plant defence responses can be triggered by specific compounds present in insect saliva. Apyrase, a known enzyme that catalyzes the hydrolysis of adenosine triphosphate (ATP) and adenosine diphosphate (ADP) into adenosine monophosphate (AMP) and inorganic phosphorus, has recently been identified in some herbivorous insects. However, whether insect salivary apyrase induces or inhibits plant responses remains poorly understood. In this study, we identified an apyrase-like protein in the salivary proteome of the fall armyworm, Spodoptera frugiperda, named Sfapyrase. Sfapyrase was primarily expressed in the salivary gland and secreted into plants during insect feeding. Transient expression of Sfapyrase in tobacco and maize enhanced plant resistance and resulted in decreased insect feeding. Knockdown of Sfapyrase through RNA interference led to increased growth and feeding of S. frugiperda. Furthermore, we showed that Sfapyrase activates the jasmonic acid signalling pathway and promotes the synthesis of secondary metabolites, especially benzoxazinoids, thereby enhancing resistance to S. frugiperda. In summary, our findings demonstrated that Sfapyrase acts as a salivary elicitor, inducing maize jasmonic acid defence responses and the production of insect-resistant benzoxazinoids. This study provides valuable insights into plant-insect interactions and offers potential targets for developing innovative insect pest management strategies.