Fall Armyworm Spodoptera Frugiperda Research Articles

Applicability of entomopathogenic fungi and essential oils against the fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae)

Applicability of entomopathogenic fungi and essential oils against the fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae)

Effects of Vermicompost on Soil and Plant Health and Promoting Sustainable Agriculture

This review highlights the potential of vermicompost and its derived products as sustainable and eco-friendly solutions for enhancing production and pest management in grain crops. It assesses their impact comprehensively on crops such as maize, wheat, barley, rice, and pearl millet. Vermicompost improves soil quality, increases nutrient availability, boosts crop productivity, and enhances pest and disease tolerance. It acts as an organic fertilizer, enriching the soil with essential nutrients, humic acids, growth-regulating hormones, and enzymes, improving plant nutrition, photosynthesis, and overall crop quality. Furthermore, vermicompost shows promise in mitigating soil degradation and sequestering organic carbon while demonstrating the potential for pest management, including effectiveness against pests like fall armyworm (Spodoptera frugiperda). This review emphasizes the importance of integrated nutrient management and proper application strategies to maximize the benefits of vermicompost in grain crops. Factors such as the form and timing of application, efficacy against specific pests, and economic viability for different farming scales are discussed. Understanding these factors is crucial for successfully implementing and adopting vermicompost-based pest management strategies in grain crops. This review also explores the potential of vermicomposting as an eco-friendly and cost-effective solution to remediate organic contaminants, emerging contaminants, personal-care and pharmaceutical products, and microplastics. The review further identifies knowledge gaps and highlights the need for future studies to effectively utilize vermicompost and its derived products in cereal production for sustainable agriculture, contributing to global food security.

Effects of Silicon Application on Yield, Spectral Index, and Fall Armyworm (Spodoptera frugiperda) Infestation on Maize (Zea mays) Crop

This paper presents the implementation of statistical and remote sensing techniques to analyze the spectral response, grain yield, and infestation of fall armyworm (Spodoptera frugiperda) in corn (Zea mays) based on the application of edaphic and foliar treatments with silicon, comparing the results with those reported in the literature where it has been demonstrated that the incorporation of this nutrient in different crops improves the activity of the enzyme nitrate reductase and dry matter weight gain. The results show that the foliar application of silicon tends to increase grain production in the crop, while the soil treatment does not improve yield. Similarly, foliar silicon application improves the Normalized Difference Vegetation Index, which improves plant health and could be correlated with higher grain yield of the crop. An inverse correlation was detected between the use of foliar silicon and the Normalized Difference Water Index and a direct relationship in the case of direct field application. As for the analysis of the data to verify the influence of the use of silicon on fall armyworm infestation, no statistically significant evidence was found that would lead to the conclusion that the application of this element, whether in soil or foliar form, could lead to a decrease in crop infestation.

Evaluation of the resistance of three maize varieties to Spodoptera frugiperda (J.E. Smith) and Ostrinia nubilalis Hübner in the Tonkpi region (Man, Côte d’Ivoire)

BackgroundThe corn borer Ostrinia nubilalis and the fall armyworm Spodoptera frugiperda larvae feed on the aerial parts of maize. It is responsible for significant yield losses and are therefore a cause of food insecurity. This study carried out to evaluate the resistance of three maize varieties (EV8766 SR-MRP, PR9131-SR, CEW-SR), in Tonkpi region’s, to S. frugiperda and O. nubilalis damages. Each maize variety seeds were sown on a one hectare plot subdivided into 6 elementary plots with 75 cm between rows and 40 cm between bunches. Sampling of S. frugiperda and O. nubilalis larvae on maize plants was carried out according to the FAO method, from the third to the fifth week after planting. Maize plants damaged, the intensity of infestation and the number of larvae on maize plants were recorded. Maize plants damaged by the insect pests were marked to avoid recounting. At maturity, 100 maize cobs were harvested per elementary plot, then the larvae number and the attacked cobs by S. frugiperda and O. nubilalis larvae were recorded.ResultsThe lowest damage rate by S. frugiperda were recorded in maize variety EV8766-SR-MRP (23.33%); while, the highest damage rate were in the varieties PR9131-SR (43.33%) and CEW-SR (55%). There are no significant difference values of the density of S. frugiperda larvae per maize plant attacked between the three varieties. The index of intensification of maize plant damaged by S. frugiperda larvae was lower for the variety EV8766-SR-MRP (7.50%) and was moderate for the varieties PR9131-SR (15.42%) and CEW-SR (21.67%). The damage rates of O. nubilalis larvae on maize cobs varied between 9.6 and 22.0%. These damage rates were higher for the varieties PR9131-SR (21.83%) and CEW-SR (17.50%) and were lower for EV8766-SR-MRP (9.66%). There was not significantly different from the density of O. nubilalis larvae per maize cob attacked between the three varieties. It was between 1 to 1.2 larvae. Crop losses were lower for EV8766 SR-MRP (10.228%) than those of PR9131-SR and CEW-SR (19.338%).ConclusionsThe maize variety EV8766-SR-MRP is found to be the best variety in the control of, O. nubilalis and S. frugiperda.

Morphometrics of <i>Spodoptera frugiperda</i> (J E Smith) as Influenced by Cereal Hosts

This laboratory study evaluate the morphometrics of fall army worm Spodoptera frugiperda (J E Smith) influenced by four cereal host plants. In maize, larval head capsule width was 0.22, 0.42, 0.71, 1.13, 1.29 and 2.94 mm for I to VI instars, respectively in sorghum was 0.20, 0.41, 0.67, 1.06, 1.24 and 3.05 mm for I to VI instars, respectively. In pearl millet, larval head capsule width was 0.19, 0.29, 0.52, 0.83, 1.23 and 2.80 mm, for I to VI instars, respectively. In sugarcane, head capsule width was 0.22, 0.43, 0.67, 0.94, 1.22 and 2.70 mm for I to VI instars, respectively. The mean pupal length varied significantly when reared on different cereal host plants, it was significantly maximum on maize (15.10 mm) followed by sorghum (14.20 mm), sugarcane (13.10) and lowest on pearl millet (12.30 mm). The significantly maximum pupal weight was noticed on maize (185.90 mg) followed by sorghum (144.40 mg), sugarcane (124.80 mg) and lowest on pearl millet (104.70 mg).

Downregulation of a transcription factor associated with resistance to Bt toxin Vip3Aa in the invasive fall armyworm.

Transgenic crops producing insecticidal proteins from Bacillus thuringiensis (Bt) have revolutionized control of some major pests. However, more than 25 cases of field-evolved practical resistance have reduced the efficacy of transgenic crops producing crystalline (Cry) Bt proteins, spurring adoption of alternatives including crops producing the Bt vegetative insecticidal protein Vip3Aa. Although practical resistance to Vip3Aa has not been reported yet, better understanding of the genetic basis of resistance to Vip3Aa is urgently needed to proactively monitor, delay, and counter pest resistance. This is especially important for fall armyworm (Spodoptera frugiperda), which has evolved practical resistance to Cry proteins and is one of the world's most damaging pests. Here, we report the identification of an association between downregulation of the transcription factor gene SfMyb and resistance to Vip3Aa in S. frugiperda. Results from a genome-wide association study, fine-scale mapping, and RNA-Seq identified this gene as a compelling candidate for contributing to the 206-fold resistance to Vip3Aa in a laboratory-selected strain. Experimental reduction of SfMyb expression in a susceptible strain using RNA interference (RNAi) or CRISPR/Cas9 gene editing decreased susceptibility to Vip3Aa, confirming that reduced expression of this gene can cause resistance to Vip3Aa. Relative to the wild-type promoter for SfMyb, the promoter in the resistant strain has deletions and lower activity. Data from yeast one-hybrid assays, genomics, RNA-Seq, RNAi, and proteomics identified genes that are strong candidates for mediating the effects of SfMyb on Vip3Aa resistance. The results reported here may facilitate progress in understanding and managing pest resistance to Vip3Aa.

One stone for two birds: Endophytic fungi promote maize seedlings growth and negatively impact the life history parameters of the fall armyworm, Spodoptera frugiperda.

The fall armyworm (FAW) Spodoptera frugiperda, is a voracious pest of cereals native to the Americas and which invaded Africa in 2016. Chemical control is the main management option, which however remains ineffective and unsustainable. Fungal endophytes are increasingly used as alternative for the management of insect pests of economic importance. This study assessed the potential of eight endophytic fungal isolates to colonize maize plant and their ability to promote seedlings growth through seed and foliar inoculations, as well as their suppressive effects on FAW. Fungal colonization rates of different plant parts by the endophytes varied as per the inoculation methods. Beauveria bassiana ICIPE 279 colonized more than 60% of all the seedling parts while B. bassiana G1LU3 only colonized stem (25%) and leaf (5%) tissues through foliar inoculation. Trichoderma atroviride F2S21, T. asperellum M2RT4, T. harzianum F2R41, Trichoderma sp. F2L41, Hypocrea lixii F3ST1 and Fusarium proliferatum F2S51 successfully colonized all the plant parts and therefore were selected and further evaluated through seed inoculation for their endophytic persistence, effect on plant growth, and pathogenicity to Spodoptera frugiperda immature and adult stages. Weekly assessment showed varied effect of the endophytes on maize plant growth parameters compared to the control. During the first week, percentage colonization of the plant parts ranges between 90%-100%, 65%-100%, and 60%-100%, in the roots, stems, and leaves, respectively for all the five tested isolates. However, the colonization pattern/rates significantly decreased over time for H. lixii F3ST1 in the stems and leaves, and for T. harzianum F2R41 in the leaves and for T. asperellum M2RT4 in the roots. In addition, T. harzianum F2R41 outperformed all the other isolates in boosting the plant height, whereas H. lixii F3ST1 and T. asperellum M2RT4 outperformed all the other isolates in increasing the wet and dry shoots weight. Furthermore, the number of egg masses laid on endophytically-colonized maize plants varied among the treatments. Trichoderma asperellum M2RT4 and H. lixii F3ST1 endophytically-colonized maize plants significantly reduced the number of egg masses and the defoliation/feeding rates of the pest compared to the control. Additionally, T. harzianum F2R41 had the highest negative impact on the pupation and adult emergence of S. frugiperda with a female-biased sex ratio. Our findings indicate that T. asperellum M2RT4, T. harzianum F2R41, and H. lixii F3ST1 hold a potential to be developed as endophytic-fungal-based biopesticides for sustainable management of S. frugiperda and as plant growth promoters.

Larvicidal effect of an N-isobutyl-(2E,4E,8Z,10E/Z)-dodecatetraenamides-rich extract of Salmea scandens on fall armyworm

Aim of study: To determine if secondary metabolites present in an ethanolic extract of Salmea scandens could be considered as a viable alternative for the control of fall armyworm (Spodoptera frugiperda larvae), as this is the most important maize pest in terms of economic losses to agriculture worldwide. Area of study: S. scandens shrubs were collected in San Rafael Toltepec, Oaxaca, Mexico. The laboratory assays were conducted at CIIDIR Oaxaca, and preliminary field assay was carried out in Zaachila Oaxaca. Material and methods: N-isobutyl-(2E,4E,8Z,10E/Z)-dodecatetraenamides-rich extract of S. scandens, corroborated by nuclear magnetic resonance (1H NMR and 13C NMR) and Fourier transform infrared (FTIR), was obtained from S. scandens by 10-day maceration in ethanol. The effect of the extract on the mortality of S. frugiperda larvae was investigated in the laboratory (in vitro) by topical application, and in the field (in situ), testing both topical and spraying applications. Main results: The 1H NMR, 13C NMR and FTIR spectra evidenced the obtention of the alkylamides-rich ethanol extract of S. scandens. Mortality of S. frugiperda in vitro increased with dose and monitoring time, reaching up to 80%. Under field conditions 63% of mortality was recorded at a dose of 0.30 mg µL-1 per larva by topical application, and 49% by spray application at a dose of 0.15 mg µL-1 per larva. Research highlights: The ethanolic extract of S. scandens can be considered a viable alternative for controlling fall armyworm S. frugiperda.

Seed Treatment with Insecticides- A Potential Option against Fall Army Worm <i>Spodoptera frugiperda</i> in Maize

Spraying with insecticides is generally carried out for the management of fall army worm Spodoptera frugiperda (J E Smith) in maize. As the pest causes significant damage in the vegetative stages, seed treatment can also be an option. In the present study, seed treatment has been evaluated for its efficacy in comparison with spray in maize. The results suggested that chlorantraniliprole 62.5FS was more effective than presently used seed treatment with cyantraniliprole. In case of foliar spray, spinetoram 11.7SC along with chlorantraniliprole 18.5SC and emamectin benzoate 5SG were found effective. As seed treatment is easy to practice and economical, seed treatment with diamides, particularly chlorantraniliprole 62.5FS might provide a better alternative to foliar sprays during early crop stage. Hence, an integrated strategy involving seed treatment in combination with need-based foliar spray at later crop stages may make management of S. frugiperda more efficient.

Effect of sowing dates and cultivars on incidence of the exotic army worm Spodoptera frugiperda (J.E. Smith) of maize (Zea mays L.)

The Effect of sowing dates and cultivars on the incidence of fall army worm Spodoptera frugiperda (J.E. Smith) and yield attributes of maize (Zea mays L.) was carried out with five cultivars namely, Zarsi (local), Sipho (local), Ronimi (local), Khoi (local) and HQPM-1 (composite) and three different sowing dates (6th March, 21st March and 5th April). Among the different dates of sowing, 6th March recorded maximum pest incidence, while 5th April recorded the least on maize. The interaction between sowing dates and cultivars showed significant effect on the incidence of army worm at different days after sowing. The maize sown on 21st March, recorded the highest grain yield (4.12 t ha-1). It can be suggested that manipulating the sowing date and growing of tolerant variety of maize such as HQPM1 can be an effective measure to manage exotic army worm infestation. Mid sowing of maize (21st March) and growing of local cultivars such as Sipho observed significantly better yield attributes which will ensure higher economic returns to the farmers.

PESTICIDAL ACTIVITY OF CRUDE EXTRACTS OF ALOE SECUNDIFLORA,NICOTIANA TABACUM AND TEPROSIA VOGELII AGAINST FALL ARMYWORM (SPODOPTERA FRUGIPERDA)

The fall armyworm (FAW),Spodoptera frugiperda (Lepidoptera: Noctuidae) is a recent invasive pest species that has successfully established across sub-Saharan Africa. Management of FAW in its native range in the Americas has led to the development of resistance to many commercial pesticides before its arrival in Africa. Synthetic pesticides are often associated with issues such as pest resistance, persistent residue, non-target toxicity, and environmental issues. Therefore, the research and development of novel, safe, and effective pesticides has become a focus in pesticide discovery. Pesticide use may therefore be ineffective for FAW control in Africa, so new and more sustainable approaches to pest management are required that can help reduce the impact of FAW pest. Pesticidal plants provide an effective and established approach to pest management in African smallholder farming and recent research has shown that their use can be cost-beneficial and sustainable. In this study, crude leave extracts of three plants aloe secundiflora, nicotiana tabacum and teprosia vogelii were evaluated against fall armyworm (spodoptera frugiperda). Two different concentrations, 30mg/L and 15mg/L were evaluated in this study against second instar FAW larvae and eggs. The results indicated that these leave extracts caused a larval and egg mortalities of different levels. On average leave extracts of aloe secundiflora, teprosia vogelii and nicotiana tabacum caused larval mortalities of 80%, 63.33% and 93.33% respectively for 30mg/L concentrations while the average larval mortalities for aloe secundiflora, teprosia vogelii and nicotiana tabacum were 26.67%, 33.33% and 80.0% respectively for the 15mg/L concentrations. The egg mortalities were relatively low compared to larval mortalities for the two concentrations used in this study. On average the leave extracts of aloe secundiflora, teprosia vogelii and nicotiana tabacum caused the egg mortalities of 16.67%, 13.33% and 43.33% respectively when 30mg/L were used while the average egg mortalities for aloe secundiflora, teprosia vogelii and nicotiana tabacum were 3.33%, 0.0% and 26.67% respectively for the 15mg/L concentrations. It follows that nicotiana tabacum showed high larval and egg mortalities for both concentrations compared to the other two leave extracts and therefore good pesticide for the control FAW larvae and eggs.

Biological management options against the fall armyworm Spodoptera frugiperda causing damage to maize in Senegal

Biological management options against the fall armyworm Spodoptera frugiperda causing damage to maize in Senegal

Sub-optimal host plants have developmental and thermal fitness costs to the invasive fall armyworm.

The fall armyworm (FAW) Spodoptera frugiperda (J.E. Smith) is a global invasive pest of cereals. Although this pest uses maize and sorghum as its main hosts, it is associated with a wide range of host plants due to its polyphagous nature. Despite the FAW's polyphagy being widely reported in literature, few studies have investigated the effects of the non-preferred conditions or forms (e.g., drought-stressed forms) of this pest's hosts on its physiological and ecological fitness. Thus, the interactive effects of biotic and abiotic stresses on FAW fitness costs or benefits have not been specifically investigated. We therefore assessed the effects of host plant quality on the developmental rates and thermal tolerance of the FAW. Specifically, we reared FAW neonates on three hosts (maize, cowpeas, and pearl millet) under two treatments per host plant [unstressed (well watered) and stressed (water deprived)] until the adult stage. Larval growth rates and pupal weights were determined. Thermal tolerance traits viz critical thermal maxima (CTmax), critical thermal minima (CTmin), heat knockdown time (HKDT), chill-coma recovery time (CCRT), and supercooling points (SCPs) were measured for the emerging adults from each treatment. The results showed that suboptimal diets significantly prolonged the developmental time of FAW larvae and reduced their growth rates and ultimate body weights, but did not impair their full development. Suboptimal diets (comprising non-cereal plants and drought-stressed cereal plants) increased the number of larval instars to eight compared to six for optimal natural diets (unstressed maize and pearl millet). Apart from direct effects, in all cases, suboptimal diets significantly reduced the heat tolerance of FAWs, but their effect on cold tolerance was recorded only in select cases (e.g., SCP). These results suggest host plant effects on the physical and thermal fitness of FAW, indicating a considerable degree of resilience against multiple stressors. This pest's resilience can present major drawbacks to its cultural management using suboptimal hosts (in crop rotations or intercrops) through its ability to survive on most host plants despite their water stress condition and gains in thermal fitness. The fate of FAW population persistence under multivariate environmental stresses is therefore not entirely subject to prior environmental host plant history or quality.

Rational Design of Insecticidal Isoxazolines Containing Sulfonamide or Sulfinamide Structure as Antagonists of GABA Receptors with Reduced Toxicities to Honeybee and Zebrafish.

To develop highly effective, nontarget organism-friendly insecticides based on the isoxazoline scaffold, we rationally designed and synthesized 25 isoxazoline derivatives containing sulfonamides and sulfinamides. Their insecticidal activities against the diamondback moth (Plutella xylostella), fall armyworm (Spodoptera frugiperda), beet armyworm (Spodoptera exigua), and Spodoptera litura Fabricius (S. litura) were evaluated. The trifluoromethyl sulfinamide-containing compound 7w displayed excellent activities with LC50 values being 0.09, 0.84, 0.87, and 0.68 mg/L against P. xylostella, S. frugiperda, S. exigua, and S. litura, respectively, which were superior to fluxametamide (LC50 = 0.09, 1.24, 1.10, and 0.65 mg/L, respectively) and maintained at the same order of magnitude LC50 values as fluralaner (LC50 = 0.02, 0.17, 0.12, and 0.19 mg/L, respectively). Importantly, compound 7w showed a medium toxicity level of acute toxicity to honeybee (LD50 = 2.22 μg/adult), which is significantly lower than the fluralaner (high toxicity level, LD50 = 0.09 μg/adult). Acute toxicity experiments with zebrafish (Danio rerio) indicated that compound 7w was safe with the LC50 value being 42.4 mg/L (low toxicity level). Furthermore, electrophysiological experiments and molecular docking studies preliminarily verified that compound 7w acts on the insect GABA receptor, and the theoretical calculations explained that the sulfinamide structure may play an important role in exhibiting biological activities. The above results suggest that compound 7w could be employed as a potentially highly effective, environmentally friendly insecticide to control multiple agricultural pests.

First report of invasive fall armyworm Spodoptera frugiperda (J.E. Smith) in the province of Davao del Norte, Philippines and its damage to the corn crop

First report of invasive fall armyworm Spodoptera frugiperda (J.E. Smith) in the province of Davao del Norte, Philippines and its damage to the corn crop

Sensitivities of Fall Armyworm (Spodoptera frugiperda) Populations in Different Regions of China to Four Bt Proteins

Fall armyworm (FAW), Spodoptera frugiperda, invaded the south of China in December 2018 and has since posed a huge threat to crop production in China. However, transgenic Bacillus thuringiensis (Bt) corn can efficiently control the damage caused by FAWs. In fact, the Chinese government has issued biosafety certificates for several Bt corn hybrids expressing any one of four Bt proteins, Vip3A, Cry1F, Cry1Ab, and Cry2Ab, or combinations thereof, to control FAWs. These Bt corn events are soon to be commercialized in China. Therefore, it is necessary to monitor and evaluate whether the FAW has developed resistance to any of the Bt corn hybrids planted in fields in China. To address this issue, we collected 11 geographical populations of FAWs and determined the sensitivity of each to the aforementioned four purified Bt proteins as assessed by diet surface overlay bioassays. The ranges for the 50% lethal concentration (LC50) of the four Bt proteins to all FAW populations were as follows: 11.42–88.33 ng/cm2 (for Vip3A), 111.21–517.33 (Cry1F), 135.76–1108.47 (Cry1Ab), and 994.42–5492.50 (Cry2Ab). The corresponding ranges for the 50% growth inhibition concentrations (GIC50) were 1.43–14.86, 2.35–138.97, 1.58–464.86, and 25.01–1266.07 ng/cm2. The lethal effects and growth inhibition effects of the four Bt proteins on FAW were in the same order of Vip3A > Cry1F > Cry1Ab > Cry2Ab. A comparison with published LC50 values of Bt proteins towards sensitive FAW populations revealed that all 11 FAW populations in this study were sensitive to Vip3A, Cry1F, and Cry1Ab. This study provides foundational data for monitoring and controlling the resistance of Bt corn to FAW in China.

Invasion of fall armyworm led to the succession of maize pests in Southwest China

The invasive fall armyworm Spodoptera frugiperda (J. E. Smith) invaded Asia in 2018, colonizing the tropical and southern subtropical regions as well as migrating with the monsoons into Northeast Asia during spring and summer. This has resulted in widespread infestations, with significant impacts on maize production in various Asian countries. Previous studies have shown that the invasion of this pest can alter the species relationships of maize pests, but the actual impact on maize pest management is still unclear. This study investigated the changes in maize pest occurrence and pesticide use in the annual breeding areas of S. frugiperda in Yunnan Province and the Guangxi Zhuang Autonomous Region of China during 2017–2021, based on surveys and interviews with small farmers in maize production. The results showed that S. frugiperda has emerged as the dominant species among maize pests after invasion and colonization, replacing traditional pests such as Ostrinia furnacalis, Spodoptera litura, Agrotis ypsilon, and Rhopalosiphum maidis. The variety of pesticides used for maize pest control has changed from chlorpyrifos, lambda-cyhalothrin, and acetamiprid to emamectin benzoate-based pesticides with high effectiveness against S. frugiperda. Furthermore, the frequency of maize pest chemical applications has increased from an average of 5.88 to 7.21 times per season, with the amounts of pesticides used in summer and autumn maize being significantly higher than in winter and spring maize, thereby increasing application costs by more than 35%. The results of this study clarified the impact of S. frugiperda invasion on maize pest community succession and chemical pesticide use in tropical and south subtropical China, thereby providing a baseline for modifying the regional control strategies for maize pests after the invasion of this relatively new pest.

Generalist Predators Shape Biotic Resistance along a Tropical Island Chain.

Islands offer exclusive prisms for an experimental investigation of biodiversity x ecosystem function interplay. Given that species in upper trophic layers, e.g., arthropod predators, experience a comparative disadvantage on small, isolated islands, such settings can help to clarify how predation features within biotic resistance equations. Here, we use observational and manipulative studies on a chain of nine Indonesian islands to quantify predator-mediated biotic resistance against the cassava mealybug Phenacoccus manihoti (Homoptera: Pseudococcidae) and the fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae). Across island settings, a diverse set of generalist lacewing, spider and ladybeetle predators aggregates on P. manihoti infested plants, attaining max. (field-level) abundance levels of 1.0, 8.0 and 3.2 individuals per plant, respectively. Though biotic resistance-as imperfectly defined by a predator/prey ratio index-exhibits no inter-island differences, P. manihoti population regulation is primarily provided through an introduced monophagous parasitoid. Meanwhile, resident predators, such as soil-dwelling ants, inflict apparent mortality rates up to 100% for various S. frugiperda life stages, which translates into a 13- to 800-fold lower S. frugiperda survivorship on small versus large islands. While biotic resistance against S. frugiperda is ubiquitous along the island chain, its magnitude differs between island contexts, seasons and ecological realms, i.e., plant canopy vs. soil surface. Hence, under our experimental context, generalist predators determine biotic resistance and exert important levels of mortality even in biodiversity-poor settings. Given the rapid pace of biodiversity loss and alien species accumulation globally, their active conservation in farmland settings (e.g., through pesticide phasedown) is pivotal to ensuring the overall resilience of production ecosystems.

Opuntia ficus-indica cladode extract is a phagostimulant agent that impairs the morphophysiology of midgut of Spodoptera frugiperda (Lepidoptera: Noctuidae) caterpillars

The fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae) is a polyphagous insect whose control mainly involves the use of synthetic insecticides that can be highly toxic to non-target organisms and lead to the selection of resistant populations. This work reports the effects of the saline extract of Opuntia ficus-indica cladodes (CE) on the feeding survival and midgut morphophysiology of S. frugiperda third instar caterpillars. CE exerted a phagostimulant effect to the caterpillars but was not able to kill them. Despite of this, the midguts of caterpillars treated with CE (12.8 mg/g) showed intense disorganization of epithelium, vacuolation of the cytoplasm of columnar cells and increased size of goblet cells, as well as absence of the peritrophic membrane. The caterpillars treated with CE showed a reduction in the amount of neutral polysaccharides and protein content at the midgut epithelial cells. Together these data may indicate that the ingestion of CE in higher concentrations or by a longer period would lead the caterpillars to death or to damage in development. In conclusion, CE ingestion resulted in damage to the midgut morphology of caterpillars, with a reduction in carbohydrate and protein content.

Assessment of effectiveness of maize seed treated with cyantraniliprole and thiamethoxam for management of fall armyworm, Spodoptera frugiperda (J.E. Smith)

The effectiveness of maize seed treatments for management of fall armyworm (FAW) (Spodoptera frugiperda) was evaluated under natural infestation conditions in Zambia in 2019, 2020 and 2022. Two seed treatments were tested: cyantraniliprole (Fortenza® 600 FS) + thiamethoxam (Cruiser® 600 FS) (combination marketed as Fortenza® Duo) and Fortenza® 600 FS. Other treatments included each of the two seed treatments supplemented with threshold-based rotational sprays of Denim Fit® 50 WG (emamectin benzoate + lufenuron) and Ampligo® (chlorantraniliprole + lambda cyhalothrin), Denim Fit/Ampligo alone, untreated controls, Ecoterex® 0.5% GR (deltamethrin + pirimiphos methyl) and Mythic® FN SC (chlorantraniliprole). The incidence of FAW-infested plants and plant damage scores were recorded weekly for 4–5 weeks post-emergence. At harvest, grain yield, yield increase over untreated control and cost-benefit ratios were also determined. Although there were some seasonal variations in treatment effectiveness, plots established from Fortenza Duo-treated seed generally had significantly lower plant damage within the first 3–5 weeks of growth. The number of follow-on insecticide sprays were reduced from 2 to 1 in February 2022 plantings in plots established from Fortenza Duo-treated seed. Grain yields were highest in the Denim Fit/Ampligo plots (December 2021 plantings) and Fortenza Duo + Denim Fit/Ampligo plots (December 2021 and February 2022 plantings). In both plantings of the 2021-22 season, mean yield increase over untreated control was highest in Fortenza Duo + Denim Fit/Ampligo plots. Cost-benefit ratios were, however, highest where Fortenza Duo-treated seed was planted without any follow-on chemical sprays and lowest and negative in sole Fortenza plots. Due to method of application and systemic action, Fortenza Duo maize seed treatments may be a perfect fit in FAW integrated pest management (IPM) programs where there is need for judicious pesticide use.