Molecular and haplotype evidence of fall armyworm (Spodoptera frugiperda) invasion in western Iran

Simple SummaryThe fall armyworm (FAW) Spodoptera frugiperda (J.E. Smith) is a long-distance migratory insect pest, and the invaded range of its recent expansion includes regions colder than the tropical and subtropical regions in East Asia. Adaptation to freezing and/or chilling injury during winter is required for the successful invasion and subsequent localization of newly invaded species. The mechanisms of injury caused by low temperatures are classified into three types (freezing, cold shock, and indirect chilling), and our study shows that indirect chilling injury, which is caused by the long-term exposure of insects to moderately low temperatures (3 to 15 °C), is most important for the survival of S. frugiperda during the winter. Adult S. frugiperd were more tolerant to moderately low temperatures than the larvae and pupae, but survival decreased significantly when adult S. frugiperd were exposed to temperatures of 9 °C or lower. Survival was improved by short-term daily exposure to higher temperatures, indicating the existence of a repair process for indirect chilling injury in S. frugiperd. These findings on indirect chilling injury and the repair process will improve the estimation of the potential distribution of S. frugiperd in temperate and colder regions.The fall armyworm (FAW) Spodoptera frugiperda is a long-distance migratory insect pest, and the invaded range of its recent expansion includes regions colder than the tropical and subtropical regions in East Asia. In order to understand the potential distribution of S. frugiperd in temperate and colder regions, we quantified the effects of temperature and exposure duration on the degree of indirect chilling injury caused to S. frugiperd under laboratory conditions. The adults were more tolerant to moderately low temperatures (3 to 15 °C) than the larvae and pupae. Survival decreased significantly when adult S. frugiperd were exposed to temperatures of 9 °C or lower. A time–temperature model suggested that indirect chilling injury began occurring at 15 °C. Survival was improved by short-term daily exposure to higher temperatures, indicating the existence of a repair mechanism for indirect chilling injury in S. frugiperd. The degree of repair depended on the temperature, but the relationship was not a simple direct proportion. These findings on indirect chilling injury and repair will improve the estimation of the potential distribution of S. frugiperd in temperate and colder regions.

Influence of three insecticides targeting GABA receptor on fall armyworm Spodoptera frugiperda: Analyses from individual, biochemical and molecular levels

The occurrence of a new invasive pest species of corn, the fall armyworms Spodoptera frugiperda (Lepidoptera: Noctuidae) in Indonesia is reported. Survey in 3 provinces in Indonesia: West Sumatera, Banten and West Java were conducted from March to June 2019. The first record of this pest was in 26 March 2019 in West Sumatera. Larvae were collected from each of those locations and field symptoms of damage on corn in the field were observed. Larvae were brought to and reared individually in Insect Biosystematics Laboratory of Plant Protection Department, Faculty of Agriculture, IPB University. Identification of fall armyworm employed morphological and molecular analysis. Identification of the larva based on morphological characters of larvae from 3 provinces confirmed the identity of the pest. The pest as fall armyworms, while the molecular analysis indicated that Banten samples belonged to the ‘rice strain’. Collected larvae from Banten were infected by Metarhizium rileyi. The infested plants in the field showed the typical damage symptoms caused by the fall armyworm.

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

The present investigation was carried out at Central Research Farm (CRF), Department of Entomology, Sam Higginbottom University of Agriculture, Technology and Sciences. Prayagraj, Uttar Pradesh during Rabi season 2023-24. The experiment was laid in Randomized Block Design with eight treatments replicated thrice along with untreated control plot. Eight treatments are Imidacloprid 40% + Fipronil 40% (80 WG) @ 0.20 ml/Lit, Chlorantraniliprole 18.5% SC @ 0.20 ml/Lit, Spinetoram 11.7% SC @ 0.30 ml/Lit, Flubendiamide 39.35% SC @ 0.24 ml/Lit, Novaluron 10% EC @ 1 ml/Lit, Beauveria bassiana 5% @ 4 ml/Lit., NSKE 5% @ 50 g/lit were evaluated against fall armyworm (Spodoptera frugiperda). Study revealed that all the treatments was found significantly superior over control. The result showed that the treatments lowest mean larval population was recorded in T3 Spinetoram (1.28), followed by T1 Imidacloprid 40% + Fipronil 40% (1.58), T5 Novaluron (1.85), T4 Flubendiamide (2.09), T2 Chlorantraniliprole (2.28), T7 NSKE (2.48) and T6 Beauveria bassiana (2.67). The treatments T6 Beauveria bassiana (2.67) was least effective among all the treatments against Spodoptera frugiperda. The crop yield ranged between 44.40 q/ha to 19.24 q/ha in the treatments and benefit cost ratio ranged between 1:2.20 to 1:1.08. The plot treated with Spinetoram 11.7% SC showed highest yield and benefit cost ratio (44.40 q/ha, 1:2.20) and found to be most effective treatment next to which, Imidacloprid 40% + Fipronil 40% (80 WG) (38.8 q/ha, 1:1.98) was more effective among all other treatments, followed by Novaluron 10% EC (35.38 q/ha, 1:1.74), Flubendiamide 39.35% SC (33.30 q/ha, 1:1.68), Chlorantraniliprole 18.5% SC (31.20 q/ha, 1:1.53), NSKE 5% (28.90 q/ha, 1:1.40). Beauveria bassiana (24.40 q/ha, 1:1.34) as compared to untreated control plot (19.24 q/ha, 1:1.08). The highest cost benefit ratio was obtained in the treatment of T3 Spinetoram 11.7% SC (1:2.20), followed by T1 Imidacloprid 40% + Fipronil 40% (1:1.98), respectively.

Abstract. Labonete HJP, Fulgencio BKR, Abatay MP, Ampang MP, Ancheta DJ, Gumal SJR, Jimenez EA, Modina RMR, Yongco JE, Tabugo SRM. 2025. Design, optimization, and validation of corn-strain-specific primers for fall armyworm (Spodoptera frugiperda) detection in the Philippines. Asian J Agric 9: 844-853. The fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae) is an invasive pest that threatens corn production in the Philippines. The presence of morphologically identical corn- and rice-strains, each with distinct host preferences, complicates accurate identification. Molecular diagnostics are significant in understudied regions of the country, such as Mindanao where S. frugiperda invasions are rapidly expanding, with primers offering reliable support in pest surveillance. This study developed and optimized corn-strain-specific primers (FAWC1–FAWC5) using ancestral Cytochrome Oxidase I (COI) haplotypes (GenBank U72974, U72976) and Primer3 in Geneious Prime (v2023.2.1). In silico PCR and specificity assessments confirmed optimal primer characteristics (20-22 bp, 57.5-60.3 °C Tm, 50-55% GC), amplicon sizes of 100-250 bp, and absence of secondary structures. The standardized annealing temperature for amplification is 53.7°C to ensure efficient primer binding and workflow consistency. The applied step-wise experimental validation ensured that all primer sets adhered rigorous technical standards supported by wet-lab testing which narrowed the best-performing candidates to FAWC3, FAWC4, and FAWC5. Verification using larval samples collected from corn and rice fields in Davao Oriental and corn fields in Iligan City demonstrated reliable amplification. It confirmed the dominance of the corn-strain across the tested sites, strengthening geographic validation and consistency in primer performance fit for community-level monitoring FAWC4 exhibited broad corn-strain detection capability making it suitable for initial screening, while FAWC5 provided strong lineage-specific resolution within Philippine populations. Together, these primers form a dual-function molecular toolkit that enables accurate strain-level identification, strengthens regional monitoring programs, and supports evidence-based fall armyworm management strategies in Philippine corn-growing regions.

The fall armyworm (FAW) Spodoptera frugiperda (J. E. Smith) is a species native to the Americas. This polyphagous lepidopteran pest was first reported in Nigeria and the Democratic Republic of São Tomé and Principe in 2016, but its presence in eastern Africa has not been confirmed via molecular characterisation. In this study, FAW specimens from western and central Uganda were identified based on the partial mtDNA COI gene sequences, with mtDNA COI haplotypes matching those identified in Nigeria and São Tomé. In this study, we sequence an additional partial mtDNA Cyt b gene and also the partial mtDNA COIII gene in Ugandan FAW samples. We detected identical mitochondrial DNA haplotypes for both the mtDNA Cyt b and COI partial genes, while combining the mtDNA COI/Cyt b haplotypes and mtDNA COIII haplotypes enabled a new maternal lineage in the Ugandan corn-preferred FAW samples to be identified. Our results suggested that the African incursions of S. frugiperda involved at least three maternal lineages. Recent full genome, phylogenetic and microsatellite analyses provided evidence to support S. frugiperda as likely consisted of two sympatric sister species known as the corn-preferred and rice-preferred strains. In our Ugandan FAW populations, we identified the presence of mtDNA haplotypes representative of both sister species. It is not known if both FAW sister species were originally introduced together or separately, and whether they have since spread as a single population. Further analyses of additional specimens originally collected from São Tomé, Nigeria and throughout Africa would be required to clarify this issue. Importantly, our finding showed that the genetic diversity of the African corn-preferred FAW species is higher than previously reported. This potentially contributed to the success of FAW establishment in Africa. Furthermore, with the additional maternal lineages detected, there is likely an increase in paternal lineages, thereby increasing the diversity of the African FAW population. Knowledge of the FAW genetic diversity will be needed to assess the risks of introducing Bt-resistance traits and to understand the FAW incursion pathways into the Old World and its potential onward spread. The agricultural implications of the presence of two evolutionary divergent FAW lineages (the corn and the rice lineage) in the African continent are further considered and discussed.

Nuclear receptors HR96 and ultraspiracle from the fall armyworm (Spodoptera frugiperda), developmental expression and induction by xenobiotics

Bacillus thuringiensis (Bt) maize (Zea mays) was developed primarily for North American pests such as European corn borer (Ostrinia nubilalis). However, most Bt maize products are also cultivated outside of North America, where the primary pests are different and often have lower susceptibility to Bt toxins. As these Bt maize products are commercialized in new geographies, insect resistance management (IRM) plans for those geographies need to consider these new pest and toxin combinations, instead of assuming the same refuge strategy applies to all pests in all geographies. Before implementing an IRM plan that includes size, placement and configuration of refuge, it is useful to understand the biology and susceptibility of the important pest(s) in each geography. Fall armyworm (Spodoptera frugiperda) and black cutworm (Agrotis ipsilon) are examples of global pests with unique biology and susceptibility to Cry1F (expressed in event 1507). The initial behavioral response of each species to Cry1F maize was tested by measuring the time naive third instars spent feeding during a three-minute exposure. I also investigated whether these species had a behavioral and/or toxic response to Cry1F maize. Additional investigation of species susceptibility and ability to overcome an aversive response was conducted by exposing third-instars of each species to Cry1F maize and measuring weight gain and survival for 14 days.

The methanolic extract from aerial parts of Parthenium argentatum, afforded argentatin A and B. These compounds were evaluated for their effect on the fall armyworm (Spodoptera frugiperda). Toosendanin, a commercial insecticide derived from Melia azedarach was used as positive control. When tested for activity, using neonate larvae into the no-choice artificial diet bioassays, argentatin A, argentatin B and methanol extract caused significant growth inhibitory activity with GC50 of 17.8, 36.1 and 6.4 ppm at 7 days, respectively, and increased the development time of surviving larvae in a concentration-dependent manner with RGI values of 0.40, 0.60 and 0.26, at 25.0, 25.0 and 5.0 ppm, respectively. In addition, it was possible to observe in most of the treated groups a significant delay in the time of pupation, adult emergence and deformities. Acute toxicity against adults of S. frugiperda was also found, MeOH extract had the most potent activity with LD50 value of 3.10 ppm. In addition, MeOH extract and argentatin A caused acetylcholinesterase inhibition of 93.7% and 90.0%, at 5.0 and 50.0 ppm, respectively; whereas argentatin B had only slight inhibitory activity. Therefore, the MeOH extract was identified as insecticidal extract from P. argentatum with activity at concentrations above 15.0 ppm.

Hexamermis jengi n. sp. (Nematoda: Mermithidae) parasitizing grasshoppers and the invasive fall armyworm in Taiwan and Thailand.

South Africa experienced major outbreaks of fall armyworm (Spodoptera frugiperda) (J.E. Smith) (Lepidoptera: Noctuidae), causing direct damage by feeding on both vegetative and reproductive parts of host plant. The study was conducted to determine the level of impact of fall armyworm on small-scale maize famers after the outbreak of fall armyworm and their control strategies at Ga-Mashashane and Mankweng villages in the Limpopo province. Semi-structured questionnaire was designed to gather information on the damage caused by fall armyworm, economic impact on the local market and control measures on fall armyworm. Using a snowball sampling procedure, 63 small-scale maize farmers from the two villages of the Limpopo province, South Africa, were randomly selected for this study. The results showed that all participants could correctly identify the fall armyworm and reported it as the most important maize pest during 2016–2017 cropping season. The maize yield loss experienced by affected farmers in the 2016–2017 cropping season was slightly lower as compared with the 2015–2016 harvest. These farmers used pesticides as a control measure for fall armyworm. Fall armyworm has become a major pest in South Africa and the tackling of fall armyworm by small-scale farmers and averting yield losses is thus critical. This study contributes to the knowledge on fall armyworm management by small-scale farmers, which is essential to enhancing food security.

BackgroundThe Fall armyworm (FAW) Spodoptera frugiperda (Lepidoptera: Noctuidae) is now established across the African continent and is a highly polyphagous and destructive pest of many crops. In Uganda, FAW has become the major maize pest, causing heavy damage especially on shoots and growing points. The objectives of this study were to: (i) document local farming practices that have been useful to manage FAW, (ii) establish farmers’ perspective on the time of FAW’s arrival to their localities, (iii) investigate the economic impact (yield) of FAW to maize farmers, (iv) establish the farmers’ perception on the current status of the FAW, and (v) document alternative practices used to manage the FAW and the perceived efficacies.MethodsA questionnaire survey was undertaken in November 2020 in Kamuli and Namutumba districts of Uganda and 99 farmers were interviewed to understand their profiles and perceptions about the FAW. A descriptive analysis of this data was undertaken to establish the socio-economic profiles and perceptions of the farmers.ResultsFarmers’ education levels in the two districts ranged from basic (completed primary education) to advanced (completed University degree), with most farmers having 10–30 years experience in growing maize (F = 20.8; df = 3,7; P = 0.0067), and with mainly small- and mid-sized production scales (F = 436.2; df = 2,5; P = 0.0002). Famers in Kamuli (98%) and Namutumba (96%) reported 25–50% yield losses due to FAW infestation that negatively impacted their income. We found a significantly higher percentage of farmers (84% and 92% in Kamuli and Namutumba districts, respectively), could correctly identify the FAW by its appearance (P < 0.0001). While FAW was officially reported in Uganda in 2016, farmers confirmed noticing damage symptoms similar to those caused by FAW as early as 2013 and 2014 in Namutumba and Kamuli districts, respectively. 98% of the farmers in Kamuli and 96% of those in Namutumba strongly agreed that FAW infestation reduced their income, while 74% in Kamuli and 86% in Namutumba also strongly considered the FAW as a threat to maize production (P < 0.0001). The majority of farmers (64% in Kamuli, 82% in Namutumba) still considered the FAW to be a very serious challenge to maize production in their localities, six years since officially being reported in Uganda. To manage the FAW, 84% and 90% of Kamuli and Namutumba respondents respectively, predominantly use chemical control methods. Other methods used also included cultural control practices (i.e., by regular weeding and handpicking), while the use of biological extracts (pepper, tobacco, Aloe-vera, Lantana, sisal) was evident though not common. Pheromones and biological control methods to manage FAW were not reported, although a farmer in Kamuli district reportedly observed weaver birds (Ploceus spp.) predating on the FAW in maize. A small number of farmers (ca. 4%) in both districts reportedly took no intentional action against FAW.ConclusionsThe farmers believe they can manage FAW if they have the appropriate and efficacious chemical insecticides as they are able to correctly apply them and follow recommended procedures. The farmers advocated for an area-wide approach as one of the best alternatives to manage this invasive pest.

Indiscriminate use of synthetic pesticides is likely to give rise to fall armyworm (Spodoptera frugiperda) resistance and environmental pollution which may result in poisoning of human. In view of these, there is need to develop naturally occurring insecticides which may be less toxic to man and animals but as effective against fall armyworm (Spodoptera frugiperda) of various cereals as synthetic insecticides. Field research was carried out in the Teaching and Research Farm of Federal University of Technology, Minna to evaluate the effect of Jatropha oil on the management of fall armyworm. The experiment was arranged in Randomised Complete Block Design (RCBD) with three replicates and six varieties. 45 ml/ L of Jatropha oil was applied every week for four weeks using Knapsack sprayer. Data on severity of fall armyworm infestation, plant height, stem diameter, number of ears, number of rotten ears, fresh and dry cob weight and grain yield were subjected to Analysis of Variance (ANOVA) the means were separated using Duncan Multiple Range Test (DMRT). The results indicated that OPV maize variety recorded the highest grain yield while Oba super 6 demonstrated a tolerance against the infestation of fall armyworm (Spodoptera frugiperda). Therefore, farmers could plant OPV maize variety for its high grain yield and Oba super 6 for its tolerant against the infestation of fall armyworm.

ABSTRACTThis paper reports for the first time on farmers’ knowledge, perceptions and management practices of the fall armyworm (Spodoptera frugiperda) in Ethiopia and Kenya. A survey of 343 smallholder maize farmers was conducted. Most farmers in Ethiopia and Kenya had knowledge about fall armyworm; they could identify it mainly during its larval stage. Furthermore, most farmers in Ethiopia (93%) and Kenya (97%) encountered damage by fall armyworm in their farms. They estimated an average of 32% crop damage in Ethiopia and 47.3% of crop damage in Kenya, with an estimated yield reduction between 0.8 to 1 tonnes/ha. Nearly half of the farmers relied on chemical insecticides to control this pest. The majority (60%) of the farmers in Kenya perceived that insecticides were not effective in controlling fall armyworm as compared to most farmers (46%) in Ethiopia who perceived that chemical spray is effective for the control of fall armyworm. In Ethiopia, 26% of the farmers combined handpicking larvae with insecticide sprays, whilst 15% of the farmers practiced only handpicking. The present study highlights the need to develop management strategies for fall armyworm based on farmers’ needs and priorities.