Fall Armyworm Spodoptera Frugiperda Research Articles

Effects of fast and slow-wilting soybean genotypes on fall armyworm (Spodoptera frugiperda) growth and development

ABSTRACT Soybean (Glycine max) is the most important plant protein source, and Fall Armyworm (FAW, Spodoptera frugiperda) is considered a major pest. This study aimed to examine the impact of FAW feeding on soybean accessions that vary in their water use efficiency (WUE) traits, by examining FAW growth and life history parameters along with plant growth response to pest damage. Soybean accessions were grown in a greenhouse and exposed to FAW larval feeding for 48 h at three different soybean growth stages: V3, R3, and R6. The growth and development of the FAW and soybeans were monitored. Results showed that faster wilting soybean accessions grow taller and have more leaves than slower wilting accessions, but yield was higher in slower wilting soybean accessions. FAW experienced the highest mortality on mid-stage (R3) soybean plants, but they gained the least mass on early stage (V3) soybean plants. These results can assist in better understanding plant insect-interactions at different life stages in both soybean and FAW with implications for management.

Toxicity of Bt Protein on Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) Fed With Corn Leaves in Paraguay

The fall armyworm Spodoptera frugiperda is the most destructive pest in corn cultivation in Paraguay with yield losses of 20 to 70%. The adoption of genetically modified crops (GMO) is a valid technique for managing this pest. The objective of this investigation was to evaluate the toxicity among Bt events used locally; determining mortality and important biological parameters. The S. frugiperda population previously collected from the field was raised under laboratory conditions fed with leaves from events MIR162TM (Vip3A19), VT3ProTM (Cry1A105, Cry2Ab2, Cry3Bb), PowerCoreTM (Cry1A105, Cry1F, Cry2Ab2) and a treatment with non-maize. Bt BR106TM. The mortality of 120 larvae was evaluated for each treatment and the viability until the adult stage of those larvae that managed to survive the different treatments was observed. A high toxicity effect was verified with 100% mortality of neonatal larvae fed with the MIR162TM (Vip3A19) event; as for the other events, 86% and 61% VT3ProTM (Cry1A105, Cry2Ab2, Cry3Bb), and PowerCoreTM (Cry1A105, Cry1F, Cry2Ab2) respectively; with 13% mortality for the non-Bt control variety BR106TM. The oviposition period, viability and number of eggs laid in adults surviving the PowerCoreTM (Cry1A105, Cry1F, Cry2Ab2) and VT3ProTM (Cry1A105, Cry2Ab2, Cry3Bb) events were reduced, affecting the fecundity of the surviving insect population.

Toxicity of Bt Protein on Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) Fed With Corn Leaves in Paraguay

The fall armyworm Spodoptera frugiperda is the most destructive pest in corn cultivation in Paraguay with yield losses of 20 to 70%. The adoption of genetically modified crops (GMO) is a valid technique for managing this pest. The objective of this investigation was to evaluate the toxicity among Bt events used locally; determining mortality and important biological parameters. The S. frugiperda population previously collected from the field was raised under laboratory conditions fed with leaves from events MIR162TM (Vip3A19), VT3ProTM (Cry1A105, Cry2Ab2, Cry3Bb), PowerCoreTM (Cry1A105, Cry1F, Cry2Ab2) and a treatment with non-maize. Bt BR106TM. The mortality of 120 larvae was evaluated for each treatment and the viability until the adult stage of those larvae that managed to survive the different treatments was observed. A high toxicity effect was verified with 100% mortality of neonatal larvae fed with the MIR162TM (Vip3A19) event; as for the other events, 86% and 61% VT3ProTM (Cry1A105, Cry2Ab2, Cry3Bb), and PowerCoreTM (Cry1A105, Cry1F, Cry2Ab2) respectively; with 13% mortality for the non-Bt control variety BR106TM. The oviposition period, viability and number of eggs laid in adults surviving the PowerCoreTM (Cry1A105, Cry1F, Cry2Ab2) and VT3ProTM (Cry1A105, Cry2Ab2, Cry3Bb) events were reduced, affecting the fecundity of the surviving insect population.

In Vivo and In Vitro Interactions between Exopolysaccharides from Bacillus thuringensis HD270 and Vip3Aa11 Protein.

Bacillus thuringiensis (Bt) secretes the nutritional insecticidal protein Vip3Aa11, which exhibits high toxicity against the fall armyworm (Spodoptera frugiperda). The Bt HD270 extracellular polysaccharide (EPS) enhances the toxicity of Vip3Aa11 protoxin against S. frugiperda by enhancing the attachment of brush border membrane vesicles (BBMVs). However, how EPS-HD270 interacts with Vip3Aa11 protoxin in vivo and the effect of EPS-HD270 on the toxicity of activated Vip3Aa11 toxin are not yet clear. Our results indicated that there is an interaction between mannose, a monosaccharide that composes EPS-HD270, and Vip3Aa11 protoxin, with a dissociation constant of Kd = 16.75 ± 0.95 mmol/L. When EPS-HD270 and Vip3Aa11 protoxin were simultaneously fed to third-instar larvae, laser confocal microscopy observations revealed the co-localization of the two compounds near the midgut wall, which aggravated the damage to BBMVs. EPS-HD270 did not have a synergistic insecticidal effect on the activated Vip3Aa11 protein against S. frugiperda. The activated Vip3Aa11 toxin demonstrated a significantly reduced binding capacity (548.73 ± 82.87 nmol/L) towards EPS-HD270 in comparison to the protoxin (34.96 ± 9.00 nmol/L). Furthermore, this activation diminished the affinity of EPS-HD270 for BBMVs. This study provides important evidence for further elucidating the synergistic insecticidal mechanism between extracellular polysaccharides and Vip3Aa11 protein both in vivo and in vitro.

The potency of fungal entomopathogens isolated from Spodoptera frugiperda as endophytic plant-growth promoter

Previous studies have identified endophytic fungi as plant growth promoters and insect pest management. In the current study, six fungal isolates of Metarhizium anisopliae and Beauveria bassiana were isolated from larval corpses of fall armyworm (Spodoptera frugiperda) and tested for their ability to colonize leaf tissue through root and leaf applications or foliar-spray and to promote the growth of young maize (Zea mays) plants. The maize growth attributes examined were germination rate, height, dry and fresh weight, and leaf area. The research was conducted in May until June 2023 in Universitas Sriwijaya, Indonesia. The results revealed that M. anisopliae and B. bassiana were isolated from the cadavers of S. frugiperda and confirmed to be endophytic fungi. Root application was more effective to enhance the fresh weight, plant height, and leaf area of maize compared to foliar-spray. The fungi could significantly enhance the fresh weight, plant height, and leaf area of the young maize plants. The best isolate that could enhance the maize growth was the B. bassiana WTTJC260521A isolate. These findings suggest that M. anisopliae and B. bassiana isolated from fall armyworm corpses that had the potential to enhance maize plant growth through root applicaton.

Characterization of core maize volatiles induced by Spodoptera frugiperda that alter the mating-mediated approach-avoidance behaviors of Mythimna separata

The fall armyworm (Spodoptera frugiperda) is an invasive species and a destructive pest of maize, which significantly impacts native species and communities via complex mechanisms like competition for resources. However, the interaction between S. frugiperda and local pests remains unclear. In this study, we determined that Oriental armyworm (Mythimna separata) females with different mating status displayed different approach-avoidance behaviors towards maize which was damaged by S. frugiperda larvae. The virgin M. separata females were repelled, while the mated females were attracted by the S. frugiperda-damaged maize. To further understand the olfactory mechanism of this phenomenon, seven volatiles induced by S. frugiperda in maize were characterized by gas chromatography and mass spectrometry (GC-MS), including trans-2-hexenal, linalool, trans-β-farnesene, cis-3-hexenyl acetate, β-caryophyllene, trans-α-bergamotene, and isopentyl acetate. Additionally, electrophysiological and behavioral assays of the seven compounds were performed using both virgin and mated females of M. separata. We determined that virgin and mated females displayed different responses to the HIPV compounds. Trans-β-farnesene was the core compound for repelling virgin females, and trans-2-hexenal was the key attractant for oviposition in mated female M. separata individuals. These findings help our comprehension of the relationships between maize pests and offer new possibilities for controlling them by olfactory-based strategies.

Biodiversity loss impacts top-down regulation of insect herbivores across ecosystem boundaries

Biodiversity loss, as driven by anthropogenic global change, imperils biosphere intactness and integrity. Ecosystem services such as top-down regulation (or biological control; BC) are susceptible to loss of extinction-prone taxa at upper trophic levels and secondary ‘support’ species e.g., herbivores. Here, drawing upon curated open-access interaction data, we structurally analyze trophic networks centered on the fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae) and assess their robustness to species loss. Tri-partite networks link 80 BC organisms (invertebrate or microbial), 512 lepidopteran hosts and 1194 plants (including 147 cultivated crops) in the Neotropics. These comprise threatened herbaceous or woody plants and conservation flagships such as saturniid moths. Treating all interaction partners functionally equivalent, random herbivore loss exerts a respective 26 % or 108 % higher impact on top-down regulation in crop and non-crop settings than that of BC organisms (at 50 % loss). Equally, random loss of BC organisms affects herbivore regulation to a greater extent (13.8 % at 50 % loss) than herbivore loss mediates their preservation (11.4 %). Yet, under moderate biodiversity loss, (non-pest) herbivores prove highly susceptible to loss of BC organisms. Our topological approach spotlights how agriculturally-subsidized BC agents benefit vegetation restoration, while non-pest herbivores uphold biological control in on- and off-farm settings alike. Our work underlines how the on-farm usage of endemic biological control organisms can advance conservation, restoration, and agricultural sustainability imperatives. We discuss how integrative approaches and close interdisciplinary cooperation can spawn desirable outcomes for science, policy and practice.

An integrated control model (chemical and biological) via fuzzy linear programming for \textit{Spodoptera frugiperda} (Lepidoptera: Noctuidae)

This paper proposes an integrated control model that enables the pesticide use according to the prey density and the insertion of the natural enemy, the predators, by fuzzy linear programming. The fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae) is one of the main resistant pests of corn, which can cause damage to the productivity up to 34%. The control is strictly chemical.

Electrophysiological and behavioural responses of fall armyworm Spodoptera frugiperda: A potential phytovolatile technology for its management

The fall armyworm (FAW), scientifically known as Spodoptera frugiperda (J.E. Smith) (Lepidoptera:Noctuidae), is an invasive and polyphagous pest associated with maize (Zea mays L.). An experiment was conducted during 2020–21 at South Eastern University of Sri Lanka, Oluvil, Sri Lanka and the Coconut Research Institute of Sri Lanka Lunuwila, Sri Lanka to investigate the olfactory perception of 22 host plant volatiles by electroantennogram (EAG) and behavioural assays for males, virgin and mated females of FAW. The findings indicated that trans-2-Hexen-1-ol, Benzaldehyde, Nonanoic acid, cis-3-Hexen-1-ol, and 4-Phenyl-2-butanone elicited elevated EAG responses in FAW antennae. Additionally, β-Citronellol and ethyl butyrate elicited amplified responses specifically in mated females and males, respectively. Dose-response study revealed that the observed responses remained statistically non-significant (P>0.05), regardless gender or physiological condition of females across the 1%, 5%, 10% and 15% dose intervals. In behavioural study, observed that 1% Benzaldehyde attracted a substantial number of moths to the treatment side for both virgin and mated females, whereas 1% β-Citronellol displayed repellent properties specifically for mated females of FAW. Therefore, these findings suggest that volatile plant compounds may serve as a theoretical basis for devising novel control strategies for FAW. This includes the potential development of attractants, repellents, and mass capture killers effective for both males and females of FAW, in addition to the currently used female sex pheromone.

Prevalence of strain (R and C strains) of fall armywormSpodoptera frugiperda in eastern India

An invasive alien pest, fall armyworm has been recently introduced to India. To date, two strains of FAW have been documented, viz. R strain (rice) and C strain (corn) without any clear biological attributes, even though differences are evident. A survey was conducted during 2020–22 over 18 field visits across the eastern part of India (Bihar, West Bengal, Orissa and Jharkhand) to isolate the genetic diversification of FAW populations collected from maize. This investigation was done with a mitochondrial-based ‘universal primer’ using mtCOI (mitochondrial cytochrome c oxidase subunit I) sequence analyses revealed that both strains (R strain and C strain) were present with the FAW. Interestingly, our comprehensive analysis indicates the dominance of the R strain over the C strain in the sample collected from the eastern part of India. This would be the first report from the eastern part of India, mainly the regions of Bihar, West Bengal, Orissa and Jharkhand, where FAW primarily feeds on maize. This study generates an idea about a probable incursion by a genetic asset of FAW in India, which needs dissection of the haplotype.

Cellulose nanocrystal filled synthetic rubber: Sustainable production, environmental assessment and end-of-life biodegradation by polyphagous pests

Plastic and rubber productions have reached staggering levels, leading to environmental concerns and accumulation of microplastics (MPs) rising in ecosystems. Rubber tires, a major source of MPs, pose further challenges due to excessive use of carbon black (CB) nanofillers in their manufacturing process, stresses on adding the element of sustainability to these products. This study emphasizes on the production of bio-based cellulose nanocrystals (CNC) filled synthetic rubber with sustainability assessment through life cycle assessment (LCA). It investigates the end-of-life (EOL) biodegradation potentials of rubber waste using a polyphagous pest, fall armyworm (FAW) (Spodoptera frugiperda). The results revealed that the production of CNC filled rubber demonstrate enhanced modulus compared to CB nanofillers, while requires substantial resource consumption, impacting abiotic resource depletion–fossil fuels (ADPf), freshwater ecotoxicity (CTUe), global warming potential (GWP), particulate matter (PM) and other impact categories. Emissions associated with CNC filled rubber during EOL phase are comparatively lower than CB, rendering CNC based rubbers a potentially viable choice from an environmental sustainability perspective. EOL pest biodegradation of CNC filled rubber showed negligible to no discernible physiological effects, potentially attributed to the presence of a diverse gut microbiota community in FAW (S. frugiperda). These findings highlight the relationship between physiochemical properties and CNC biodegradability in synthetic rubbers, aiding the development of sustainable EOL strategies for rubber waste management.

Biological strategies to control caterpillars in soybean, cotton and maize in the main producing regions of Brazil

Soybean, cotton and maize crops represent some of the main agricultural commodities grown during the hot season in Brazil. In order to provide more effective control options to producers, it is essential to deepen studies on management strategies using biological insecticides. This study aims to evaluate the effectiveness of the application of the bioinsecticide Ocimum basilicum, in controlling the caterpillar complex, notably the looper (Chrysodeixis includens) in soybeans, the fall armyworm (Spodoptera frugiperda) in maize and the cotton leafworm caterpillar (Alabama argillacea) in cotton, as a control alternative aimed at mitigating damage and contributing to more sustainable agricultural practices. Experiments were carried out in each culture in various environments in the states of MT, MS, SP and PR in Brazil. A randomized block design with four replications was used in all the experiments. Agronomic traits, insect pest incidence and insecticide efficiency were evaluated for each of the crops. The data were subjected to after being subjected to stratified analysis of variance for each experimental phase. The interaction significant interactions were broken down to simple effects using Tukey's multiple comparison test of means at 5% probability. Subsequently, Scott-Knott mean grouping was used at 5% probability. Management using 1L per hectare of basil extract (Ocimum basilicum L) demonstrated satisfactory efficacy in controlling the caterpillar complex, approaching the results obtained with traditional chemical control.

Functional transgenes in Mexican maize: benefits and risks for insect pest management in Mexico and the United States

Abstract Corn earworm (Helicoverpa zea) and fall armyworm (Spodoptera frugiperda) are major migratory pests of maize (Zea mays) in the United States and Mexico. They are primarily controlled in the United States with genetically engineered (GE) maize, while the 25-yr moratorium on cultivating GE maize in Mexico has forced growers to control these pests with insecticides, where maize productivity remains 35% below the world’s average. The United States annually exports 5% of its maize grain to Mexico, where it provides human food and animal feed. This seed is often sown by smallholder growers, leading to plantings of GE transgene-expressing maize and potential hybridization with local landraces. As a result, transgenes are now present in Mexican maize products and landraces. In this study, we examined the F1 offspring of GE maize to better understand the frequency of different transgenes expressed in maize seeds exported to Mexico. We show that exported seed contains numerous transgenes, including an estimated ~68% epsps expressing resistance to the herbicide glyphosate; ~80% pat and bar expressing resistance to the herbicide glufosinate; and ~82% Bacillus thuringiensis (Bt) genes that effectively protect maize plants from several insect pests. We tested 134 samples, including landraces from 10 Mexican states, and found that 35% expressed resistance to glyphosate and 33% to glufosinate. Many samples containing herbicide resistance also expressed 11%–100% functional Bt transgenes, which can effectively reduce the refuge area provided by Mexican maize and increase the Bt-resistant allele frequency. We discuss ways that the introgression of transgenes could provide pest management benefits to Mexican growers but, at the same time, accelerate the development of Bt-resistance in corn earworm and fall armyworm. Our cost-effective screening methods can be used to determine the introgression of functional herbicide resistance and Bt transgenes in maize.

Susceptibility of immature Telenomus remus, an egg parasitoid of Spodoptera frugiperda (J.E. Smith), to entomopathogenic fungi from South Sumatra, Indonesia

BackgroundThe fall armyworm (FAW) Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) is a newly introduced pest that damages maize production in Indonesia. To control this pest in maize fields, better solution is to use the egg parasitoid, such as Telenomus remus Nixon (Hymenoptera: Scelionidae), as another better option to apply topically entomopathogenic fungi (EPF). Therefore, it is necessary to study the effect of the EPF on the egg parasitoid of T. remus. The objective of this research was to evaluate susceptibility of immature T. remus to the EPFs, Beauveria bassiana, Chaetomium sp., Curvularia lunata, Penicillium citrinum, and Metarhizium anisopliae. The EPFs (1 × 106 conidia mL−1) were sprayed topically on one-day-old mummies (immature T. remus) in post-parasitism periods.ResultsThe results showed that the cumulative percentage of T. remus adult emergence from the mummies treated with EPF on 11 days after treatment ranged 54–100% and was non-significantly different than those of control (untreated with EPF) (90.48%). Therefore, the immature stage of T. remus was not susceptible to the EPF topical application. The EPFs were harmless to the immature stage of T. remus. Percentage of aborted mummies (embryonic death) of T. remus after treated with the EPF was also non-significantly different than those of control. However, the EPFs could significantly affect developmental times of immatures stages of T. remus. The EPF also could shorten the adult longevity of the egg parasitoid.ConclusionsThe immature T. remus is less sensitive to the EPFs; B. bassiana, Chaetomium sp., C. lunata, P. citrinum, and M. anisopliae. It can be considered integrating the EPF with T. remus inundation in maize field. However, it is necessary to limit the topical application of the EPF to avoid negative effects on the adult longevity of the egg parasitoid. Thus, it needed to be further investigated that the application of the endophytic EPFs by inoculating the fungi within the plant tissue could be harmless to the egg parasitoids.

Molecular mechanisms of cytochrome P450-mediated detoxification of tetraniliprole, spinetoram, and emamectin benzoate in the fall armyworm, Spodoptera frugiperda (J.E. Smith).

The fall armyworm (FAW) Spodoptera frugiperda (J.E. Smith) is a highly damaging invasive omnivorous pest that has developed varying degrees of resistance to commonly used insecticides. To investigate the molecular mechanisms of tolerance to tetraniliprole, spinetoram, and emamectin benzoate, the enzyme activity, synergistic effect, and RNA interference were implemented in S. frugiperda. The functions of cytochrome P450 monooxygenase (P450) in the tolerance to tetraniliprole, spinetoram, and emamectin benzoate in S. frugiperda was determined by analysing changes in detoxification metabolic enzyme activity and the effects of enzyme inhibitors on susceptibility to the three insecticides. 102 P450 genes were screened via transcriptome and genome, of which 67 P450 genes were differentially expressed in response to tetraniliprole, spinetoram, and emamectin benzoate and validated by quantitative real-time PCR. The expression patterns of CYP9A75, CYP340AA4, CYP340AX8v2, CYP340L16, CYP341B15v2, and CYP341B17v2 were analysed in different tissues and at different developmental stages in S. frugiperda. Silencing CYP340L16 significantly increased the susceptibility of S. frugiperda to tetraniliprole, spinetoram, and emamectin benzoate. Furthermore, knockdown of CYP340AX8v2, CYP9A75, and CYP341B17v2 significantly increased the sensitivity of S. frugiperda to tetraniliprole. Knockdown of CYP340AX8v2 and CYP340AA4 significantly increased mortality of S. frugiperda to spinetoram. Knockdown of CYP9A75 and CYP341B15v2 significantly increased the susceptibility of S. frugiperda to emamectin benzoate. These results may help to elucidate the mechanisms of tolerance to tetraniliprole, spinetoram and emamectin benzoate in S. frugiperda.

Sphingomonas bacteria could serve as an early bioindicator for the development of chlorantraniliprole resistance in Spodoptera frugiperda

The fall armyworm (Spodoptera frugiperda) was found to have invaded China in December 2018, and in just one year, crops in 26 provinces were heavily affected. Currently, the most effective method for emergency control of fulminant pests is to use of chemical pesticides. Recently, most fall armyworm populations in China were begining to exhibite low level resistance to chlorantraniliprole. At present, it is not possible to sensitively reflect the low level resistance of S. frugiperda by detecting target mutation and detoxification enzyme activity. In this study we found that 12 successive generations of screening with chlorantraniliprole caused S. frugiperda to develop low level resistance to this insecticide, and this phenotype was not attribute to genetic mutations in S. frugiperda, but rather to a marked increase in the relative amount of the symbiotic bacteria Sphingomonas. Using FISH and qPCR assays, we determined the amount of Sphingomonas in the gut of S. frugiperda and found Sphingomonas accumulation to be highest in the 3rd-instar larvae. Additionally, Sphingomonas was observed to provide a protective effect to against chlorantraniliprole stress to S. frugiperda. With the increase of the resistance to chlorantraniliprole, the abundance of bacteria also increased, we propose Sphingomonas monitoring could be adapted into an early warning index for the development of chlorantraniliprole resistance in S. frugiperda populations, such that timely measures can be taken to delay or prevent the widespread propagation of resistance to this highly useful agricultural chemical in S. frugiperda field populations.

Transgenerational effect of a tea saponin–matrine mixture promotes fecundity and alters associated bacteria in the fall armyworm Spodoptera frugiperda

The fall armyworm Spodoptera frugiperda is a one of the most invasive and damaging pests that causes serious economic losses in several crops. Botanical insecticides such as tea saponin and matrine, as environmentally acceptable biopesticides, are widely used for controlling pests. Insecticide stress affects both individuals and the associated bacteria in insects. However, it remains unclear that if sublethal effects and bacteria are the drivers for the adaptive mechanisms of insecticides in fall armyworm. We examined the effectiveness of a 10:1 v/v mixture of biological insecticides against the fall armyworm and the impacts of several biological parameters and demographic variables of the armyworm targeting two generations at primary exposure. Moreover, the influence of the insecticide mixture on the associated bacteria of the fall armyworm was assessed via 16 S rRNA sequencing. The results showed that the mixture was highly toxic to fall armyworms, and the fecundity of the initially exposed generation (F0) significantly decreased; however, there was no significant effect on longevity. The larval duration, the total pre-reproductive period, longevity, fecundity, and mean generation time of the fall armyworm in the F1 significantly increased; yet the intrinsic and finite rates of the increase and the net reproductive rate remained fairly constant. Additionally, the population of associated bacteria was affected in both generations, with an increase in the microbial diversity within the fall armyworm compared to that of the F0 generation. Also, an increase in abundance of several genera of bacteria, including Acinetobacter, Serratia, Enterococcus, and Pseudomonas, was noted following treatment with the insecticide mixture. These results broaden our understanding of the impact of sublethal insecticide concentrations on the fall armyworm and its associated bacterial community.

Impacts of Climate Change on the Number of Days per Generation of the Egg-Parasitoid Telenomus Remus Nixon, 1937 (Hymenoptera: Scelionidae) in Egypt

In this research, we forecasted both the degree-day units and annual generations of the egg parasitoid Telenomus remus Nixon, which parasitizes fall armyworm (Spodoptera frugiperda). The aim was to comprehend its potential spread across diverse agro-climatic zones, considering both current conditions and potential future climates. This was achieved by examining the correlation between degree-day units and population fluctuations. Climate change data from the HadCM3 model was utilized, focusing on A1 scenarios recommended by the Intergovernmental Panel on Climate Change (IPCC). We aimed to evaluate how temperature projections are anticipated to impact the annual generations in three Egyptian governorates. The investigation revealed that T. remus populations in Aswan, an Upper Egyptian governorate, exhibited a higher number of generations compared to other regions, namely El Sharkia and Beni Suef governorates, in the current climate. The completion of generations by T. remus in El Sharkia, Beni Suef, and Aswan took 13.42, 12.6, and 10.08 days, respectively. The results highlighted that the average generation period in 2021 was the longest, reaching 13.42 ± 6.17 days in El Sharkia governorate. Predictions suggest that T. remus is anticipated to undergo 23 generations between 2040 and 2060, indicating a two-generation increase from 2021. Conversely, in the Beni Suef governorate, where T. remus completed generations in 10.86 ± 5.72 days, the generation period was the longest in 2021. Projections indicate that T. remus is expected to have 24 generations in 2040 and 28 generations in 2060, compared to 22 generations in 2021. Additionally, Aswan’s T. remus is forecasted to experience 32 generations in 2040 and 35 generations in 2060, up from 29 generations in the 2021 climate. The duration of the first generation took 13, 11, and 12 days in the years 2021, 2040, and 2060, respectively. A comprehensive understanding of thermal requirements and biological factors is crucial for accurately predicting generation duration, serving as a valuable reference for the mass production and preservation of parasitoids.

Control Potential of Multiple Nucleopolyhedrovirus (SfMNPV) Isolated from Fall Armyworm in Nigeria (West Africa).

The fall armyworm (FAW) Spodoptera frugiperda (Lepidoptera, Noctuidae) has now become an invasive pest of global concern. The pest was first detected in Central and Western Africa in early 2016. Sustainable management options explored by stakeholders during early FAW invasion in Africa included the use of biopesticides and biological control. The current study aimed to compare the susceptibility of FAW larvae to SfMNPV with the assumption that the virus isolated from FAW populations in Africa has higher virulence compared with an isolate from Argentina (SfMNPV-ARG). We also hypothesized that host plant plays a role in SfMNPV efficacy and that cannibalism mediates horizontal and vertical transmission of the virus. This work provides pioneering data on the virulence of the new SfMNPV isolate from Nigeria (SfMNPV-KA1), which proved more effective than its exotic counterpart from Argentina (SfMNPV-ARG). The host plant effect made a significant difference between maize and onion with more FAW death in the larvae fed with contaminated onion 5 days post treatment. The study demonstrates and discusses the effect of cannibalism on virus transmission.

Voltinism and life‐history traits of the invasive fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae) feeding on corn

AbstractVoltinism and life‐history traits of the invasive fall armyworm (FAW) Spodoptera frugiperda were investigated under semi‐natural conditions for a period of 2 years. The FAW invaded the corn field in the suburbs of Nanchang (28°46′ N, 115°50′ E) in early summer and produced six complete generations. FAW had the characteristics of short developmental time, high survival rates and strong fecundity. The development time of female pupae was significantly faster than that of male pupae, resulting in the emergence of female pupae earlier than male pupae. Except for the sixth generation in 2021, there was no significant difference between female and male sex ratio, which was close to 1:1. FAW showed male‐bias sexual size dimorphism with male pupae being significantly larger than female pupae. Unlike pupal weight, in most generations, male adult weighed significantly less than females, because the weight loss of male pupae during metamorphosis was significantly greater than that of female pupae. The temporal variation of pupal weight did not conform to the temperature–size rule. Compared with 22.8°C, the 29.2°C high temperature not only significantly reduced the development time of larvae but also significantly increased pupal weight. The adult fecundity feeding on fresh corn leaves was higher than that feeding on live corn plants in most generations. In most generations, pupal weight was positively correlated with larval development time and adult weight was positively correlated with fecundity. In conclusion, climate differences between generations and years have significant effects on developmental time, body weight, sexual size dimorphism and fecundity of the FAW. These results add to the understanding of the evolution of life‐history traits in the FAW and may have important implications for predicting population dynamics of the FAW and optimising control strategies.