Spodoptera Frugiperda Larvae Research Articles

Properties of nucleopolyhedrovirus occlusion bodies from living and virus-killed larvae of Spodoptera frugiperda (Lepidoptera: Noctuidae)

Previous studies report that the pathogenicity of nucleopolyhedrovirus occlusion bodies (OBs) is reduced if OBs are collected from living infected insects compared to virus-killed insects. We compared the production and characteristics of SfMNPV OBs collected from living and virus-killed fourth instars of Spodoptera frugiperda at 3–4 days, 5 days and 6–7 days post-inoculation. Cumulative virus-induced mortality increased from 10.5 % at 3 days to 99.6 % at 7 days post-inoculation. The production of OBs/mg larval weight increased significantly between the first and second samples, but did not increase thereafter. The total number of OBs produced in living and virus-killed larvae increased at each sample time. The size (cross-sectional area) of OBs increased significantly during the experiment, probably due to OB maturation. The median prevalence of immature OBs decreased over time from 25 to 44 % in the first samples to 9 % in the final sample. OB pathogenicity was compared in second instars that consumed a discriminating concentration of inoculum (2 × 104 OB/ml). Virus-induced mortality increased markedly in larvae that consumed OBs collected later (6–7 days) compared to OBs from earlier samples, but was similar for OBs from living or virus-killed insects at each time point. We conclude that the pathogenicity of OB samples was sensitive to the prevalence of immature OBs rather than the viral genome content of OBs, which did not differ over sample times or in OBs from living or virus-killed insects. These findings can inform decisions on the production of biological insecticides and laboratory studies on the insecticidal properties of OBs.

DEVELOPMENT OF BIOINSECTICIDES AGAINST SPODOPTERA FRUGIPERDA USING CHITINOLYTIC BACTERIA

Actinomycetes play an important role in the biological control of insects by producing insecticidal active compounds against various insects. They are predominantly found in soil, in the silt of water bodies, in the air and in plant remains. Chitinase is increasingly finding applications in various fields such as biomedicine, in ultra-structural studies, in the preparation of chitooligosaccharides, in single-cell protein production, biocontrol agents, agriculture, etc. Chitinase is originally an enzyme used by insects to degrade the structural polysaccharide of insects. Chitinase brings about hydrolysis of chitin which is widely distributed in cell wall of fungi, plants and insects. An attempt has been made to use chitinase producing bacteria for the development of bioinsecticides against Spodoptera frugiperda, which feeds on over more than 60 species of plants and it is periodic. The Spodoptera frugiperda armyworm (Lepidoptera) is a serious pest of cabbage and other crop. It is also major pest of maize, rice, sorghum, turf grasses, cotton, and peanuts, etc. In this attempt enrichment and isolation of chitinase producing bacteria from soil was carried out. Chitinolytic activities of the three isolates were tested against larvae of Spodoptera frugiperda. Three isolates were individually applied against Spodoptera frugiperda. The isolates named Ai, A2 and A3 were found to be more effective against Spodoptera frugiperda. The insecticidal activity of isolate A1was tested and control within 5 hours. Isolate A2 was treated with larvae Spodoptera frugiperda killed after 8 hours whereas, isolate A3 controlled after 24 hours. The evaluated insecticides provided a significant reduction in the infestation level, for variable periods.

Above‐ and belowground resistance in Brazilian maize varieties under attack of Spodoptera frugiperda and Diabrotica speciosa

AbstractIn South America, maize (Zea mays L., Poaceae) crops are commonly infested with larvae of Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae), known as voracious leaf feeders, as well as by larvae of Diabrotica speciosa (Germar) (Coleoptera: Chrysomelidae), a pest that destroys maize root systems. Despite the relevance of these insects to maize fields, there is no information available about the effects of these herbivores on one another. Therefore, this study aimed to evaluate in different maize varieties: (1) the influence of previous leaf consumption by S. frugiperda on D. speciosa larval weight and survival, (2) effects of previous root attack by D. speciosa on S. frugiperda larval weight and survival, and (3) the relationship between peroxidase and superoxide dismutase (resistance‐related enzymes) and maize resistance to the pests. One fifth instar S. frugiperda was released per potted maize plant at vegetative stage 4 (V4), and 24 h later plants were infested with 25 D. speciosa larvae. One set of plants was infested with D. speciosa only, and 16 days later whorl leaf sections were brought to the laboratory and offered to S. frugiperda neonate larvae. Performance of both insect pests was determined based on larval weight and survival. Uninfested plants of variety Maisena were susceptible to both herbivores. However, plants of this variety pre‐infested with S. frugiperda disfavored D. speciosa larval survival. Similarly, plants of variety Maisena pre‐infested with D. speciosa adversely affected S. frugiperda larval growth. Nevertheless, this induction of resistance was inhibited when the plant was also pre‐infested with S. frugiperda. In most cases, peroxidase and superoxide dismutase did not seem to play a role in mediating resistance to the pests. Overall, variety Maisena appears as a template for the development of maize genotypes expressing induced resistance. The potential of some varieties regarding constitutive resistance is also discussed.

Laboratory efficacy of selected synthetic insecticides against second instar invasive fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) larvae.

Maize is the most essential crop of China and its productivity has been recently endangered by the fall armyworm (FAW), Spodoptera frugiperda. Chemical pesticides are one of the most important strategies for managing FAW on a short-term basis. The seven synthetic insecticides including novel and conventional belong to four chemical group, spinetoram and spinosad (spinosyns), lambda-cyhalothrin, cypermethrin and bifenthrin (pyrethroids), abamectin (avermectins), broflinilide (diamides), were assessed for their efficiency in causing mortality to second instar S. frugiperda larvae at 24, 48 and 72 h post-treatment at five different serial concentrations (10 to 0.625 mg liter-1). The second instar S. frugiperda larvae were susceptible to the tested synthetic insecticides, however, the toxicity index of synthetic insecticides was estimated based on lethal concentration 50 (LC50), while, LC50 was calculated from the data of larval mortality. The broflanilide and abamectin proved to be the most toxic having the highest toxicity index of 100 and 78.29%, respectively, followed by cypermethrin and bifenthrin were showed toxicity index of 75.47 and 66.89%, respectively. The LC50 values were 0.606 and 0.774 mg liter-1 for broflanilide and abamectin, respectively, followed by cypermethrin and bifenthrin were showed LC50 values of 0.803 and 0.906 mg liter-1 at 72 h post-treatment. Rest of the other synthetic insecticides were showed moderate toxicity index of 42.11 to 62.09%, based on LC50 values were 1.439 to 0.976 mg liter-1 at 72 h post-treatment. The efficiency of synthetic insecticides was increased by increasing concentration level and exposure time. The screened synthetic insecticides among seven insecticides perhaps, provide basis for the development of novel insecticides for controlling S. frugiperda population after further research to evaluate and validate the laboratory results in the field.

A cost-efficient and alternative technique of managing fall armyworm Spodoptera frugiperda (J.E. Smith) larvae in maize crop

An experiment was conducted to test the efficacy of grease and emamectin benzoate in a randomized complete block design with five replications to reduce fall armyworm, Spodoptera frugiperda (J.E. Smith) larvae load from a maize field in the winter seasons of 2020 and 2021 in Sarlahi, Nepal. Standard agronomic package of practices followed for crop proper growth and development, and plant spacing maintained at 20 × 60 cm2 with a plot size of 390 m2. The treatments were applied when the maize crop was at knee height and larvae damaged nearly 5–8% of the total plants. Emamectin benzoate sprayed at 0.4 g/liter of water and grease of about 0.15 g applied to the maize whorl or tip of a drooping leaf that touched the soil. A significant reduction in larval infestation was observed after 7-days of treatment applications. Fall armyworm larvae were found dead in the chemical-sprayed plots, but they were absent in the grease-applied fields. No crop damage was observed among the grease-treated plants, which might be due to restrictions in the movement of larvae on the maize crop. The armyworm larvae might get irritated, feel insecure, and move far away from the test plots searching for food materials. Thus, an eco-friendly material like grease can be used as an agroecological method for managing fall armyworm larvae among small-scale land-holding maize farmers.

Canibalism in the larval instars of Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae): temperature and food quantity

Cannibalism is a frequent behavior in Spodoptera frugiperda (J. E. Smith, 1797) larvae either in the field or in a laboratory. The purpose of this work was to investigate the factors temperature and food quantity on the cannibal behavior in instars of this insect under laboratory conditions. The neonates were conditioned at temperatures of 22, 25, 28 and 31 ± 1°C until they reached the 3rd, 4th, and 5th instar. The number of 20 larvae were transferred to different gerbox® with the amount of food varying from 0, 5, 10, 15, and 20 g of artificial diet. Cannibalism was evaluated after 72 hours. In all the instars evaluated, the larvae showed cannibalistic behavior as a function of temperature and amount of food. The amount of 15 g of artificial diet is sufficient to feed the 3rd and 4th instar larval for 72h, regardless of temperature. For the 5th instar this amount is 10 g.

An Integrative Analysis of Transcriptomics and Proteomics Reveals Novel Insights into the Response in the Midgut of Spodoptera frugiperda Larvae to Vip3Aa.

The insecticidal Vip3 proteins, secreted by Bacillus thuringiensis (Bt) during its vegetative growth phase, are currently used in Bt crops to control insect pests, and are genetically distinct from known insecticidal Cry proteins. Compared with Cry toxins, the mechanisms of Vip3 toxins are still poorly understood. Here, the responses of Spodoptera frugiperda larvae after Vip3Aa challenge are characterized. Using an integrative analysis of transcriptomics and proteomics, we found that Vip3Aa has enormous implications for various pathways. The downregulated genes and proteins were mainly enriched in metabolic pathways, including the insect hormone synthesis pathway, whereas the upregulated genes and proteins were mainly involved in the caspase-mediated apoptosis pathway, along with the MAPK signaling and endocytosis pathways. Moreover, we also identified some important candidate genes involved in apoptosis and MAPKs. The present study shows that exposure of S. frugiperda larvae to Vip3Aa activates apoptosis pathways, leading to cell death. The results will promote our understanding of the host response process to the Vip3Aa, and help us to better understand the mode of action of Vip3A toxins.

Isolation, identification and virulence of indigenous entomopathogenic fungal strains against the peach-potato aphid, Myzus persicae Sulzer (Hemiptera: Aphididae), and the fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae)

BackgroundAs different biogeographic strains and isolates of entomopathogenic fungi vary in their genetic, enzymatic and pathogenic characteristics, this study assessed the virulence of 2 indigenous strains of Beauveria bassiana (Balsam) Vuillemin and Metarhizium anisopliae (Metschn.) Sorokin (Ascomycota, Hypocreales: Clavicipitaceae), isolated from naturally infected insect cadavers, against the 3rd instar nymphs of Myzus persicae (Sulzer) (Hemiptera: Aphididae) and 3rd instar larvae of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) using leaf-dip and larval-dip methods, respectively.ResultsBoth fungal isolates exhibited considerable pathogenicity against M. persicae and S. frugiperda. Mortality in all bioassays was conidial concentration and exposure time dependent and increased significantly along with both factors (R2 = 0.86–0.99 for B. bassiana and 0.82–0.94 for M. anisopliae). Moreover, M. anisopliae isolate appeared more virulent to S. frugiperda larvae than B. bassiana isolate, while the later fungal isolate was more lethal to M. persicae nymphs than the former one. At the highest conidial concentration (1.0 × 109 conidia/ml), M. anisopliae caused maximum mean mortality of S. frugiperda (88%) and M. persicae (65%) and B. bassiana exhibited maximum mean mortality of S. frugiperda (76%) and M. persicae (94%). Moreover, probit regression analyses showed LT50 values for M. persicae of 4.57 and 6.86 days at 1.0 × 109 conidia/ml for the isolates of B. bassiana and M. anisopliae, respectively, while LC50 values were 7.75 × 106 and 8.70 × 107 conidia/ml after 10th day of application, for the isolates of B. bassiana and M. anisopliae, respectively, against M. persicae. Similarly, LT50 values for S. frugiperda were 7.75 and 7.03 days for 1.0 × 109 conidia/ml concentration and LC50 values were 2.84 × 107 and 8.84 × 105 conidia/ml at 10th day data for the isolates of B. bassiana and M. anisopliae, respectively.ConclusionOverall study results demonstrated the effectiveness of B. bassiana and M. anisopliae against M. persicae and S. frugiperda, respectively. However, field evaluations of these indigenously isolated promising fungal strains against these insect pests.

Predation on Spodoptera Frugiperda Larvae by Different Developmental Stages of Rhynocoris Fuscipes

Predation on Spodoptera Frugiperda Larvae by Different Developmental Stages of Rhynocoris Fuscipes

A proteomic approach to identify digestive enzymes, their exocytic and microapocrine secretory routes and their compartmentalization in the midgut of Spodoptera frugiperda.

A proteomic approach was used to identify the digestive enzymes secreted by exocytosis and by microapocrine vesicles and enzyme midgut compartmentalization in Spodoptera frugiperda larvae. For this, proteomic analyses were performed in isolated midgut enterocyte microvillar membrane, in a fraction enriched in microapocrine vesicles (separated in soluble and membrane fractions), in the washings of the peritrophic membrane to isolate its loosely- and tightly-bound proteins, and in the peritrophic membrane contents. PM washings correspond to proteins extracted from the mucus layer surrounding PM. Serine endopeptidases (trypsins, chymotrypsins and serine endopeptidase homologs that have substitutions in the catalytic residues) and lipases are mainly secreted by exocytosis. Aminopeptidases are mainly microvillar enzymes and some are secreted membrane-bound to microapocrine vesicles, whereas carboxypeptidase isoforms follow different secretory routes. The results also showed that most polymer hydrolases (such as amylase and endopeptidases) are not retained in the ectoperitrophic fluid (found in PM washings but absent from PM contents). On the contrary, most enzymes involved in intermediate digestion (exemplified by carboxypeptidase and aminopeptidase) do not pass through the peritrophic membrane. Finally, the data revealed that the protein composition of PM includes peritrophins classified as peritrophic membrane proteins, PMP, and chitin deacetylase.

Biorational management of maize fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) using Bacillus thuringiensis (Berliner) enriched with chemical additives

An invasive pest, fall armyworm, Spodoptera frugiperda (J.E.Smith) (Lepidoptera: Noctuidae) attacks maize at every stage of development, from seedling emergence up to cob formation. Early instar larvae were seen mostly on leaves of maize with characteristics pin or shot hole symptoms. Later instar larvae were confined to deep whorls, leaving typically ragged like appearance and fed on the reproductive stage of the crop especially tassels and developing cobs resulting in quality and quantity loss of maize produce. The effect of commercially available Bacillus thuringiensis subsp. kurstaki product, Dipel® against the second instar larvae of Fall Armyworm (FAW )was not promising under laboratory conditions. Hence, an effort was made to add an adjuvant along with B. thuringiensis to increase the virulence of commercially available B. thuringiensis.The Laboratory bioassays with B. thuringiensis and seven chemical additives ( T1- Bt + Boric acid, T2- Bt + Zinc oxide, T3- Bt + Sodium nitrate, T4- Bt + Peptone, T5- Bt + Urea, T6- Bt + EDTA, T7- Bt + Citric acid & T8- Bt alone T9- Control) were tested against second instar larvae of Spodoptera frugiperda larvae. The results showed that B. thuringiensis plus sodium nitrate (T3) promoted maximum mortality 82.2 per cent with a minimum LC50 value of 54.620 mg/l. Sodium nitrate boosted B. thuringiensis activity at a concentration of 0.05 per cent by 2.128-fold than B. thuringiensis alone. Overall, sodium nitrate improved the efficacy of B. thuringiensis spray at the maximum level followed by boric acid, urea, EDTA and peptone.

Toxicity of entomopathogenic fungi against Spodoptera frugiperda larvae under laboratory conditions

Maize Fall Armyworm (FAW), Spodoptera frugiperda (Lepidoptera: Noctuidae) is considered an economically important pest and becoming the main threat to food security. This polyphagous pest is widely distributed in various countries of the world especially tropical and subtropical regions. The toxicity of two entomopathogenic fungi such as Metarhizium anisopliae and Beauveria bassiana were evaluated against 2nd instar larvae of FAW under controlled conditions. The results showed that among tested entomopathogenic fungi, B. bassiana was found more toxic than M. anisopliae. B. bassiana caused 79% larval mortality while M. anisopliae 59%. M. anisopliae and B. bassiana were showed LT50 of 84.01 h and 80.99 h, respectively. M. anisopliae and B. bassiana were showed LC50 of 1.3×107 and 1.8×107 spores ml−1, respectively. The current study concluded that Entomopathogenic fungi can give effective control against early instar and further studies are needed to check the efficacy against older instars under field and laboratory conditions.

Tingkat Serangan dan Musuh Alami Spodoptera frugiperda Je. Smith pada Tanaman Jagung di Lima Kecamatan di Kabupaten Banyumas

The survey of the distribution and damage of the new pest Spodoptera frugiperda is an important activity to determine appropriate control measures. In addition, the search for natural enemies is also needed as an alternative to controlling these pests. The purpose of this study was to determine the level of damage and the types of natural enemies found in several locations in Banyumas Regency. The method used is perposive random sampling in Banyumas Regency in five sub-districts, namely Ajibarang, Baturaden, Gumelar, Kedungbanteng, and Sumpiuh. Observations were made at 08.00-11.00 WIB from March to June 2021. The results showed that the attack rate of Spodoptera frugiperda larvae varied at each observation location. The highest attack rate was in Sumpiuh and Gumelar Districts, followed by Ajibarang, Kedungbanteng and Baturaden Districts. One species of parasitoid was found, namely Apanteles sp. and 9 predators, namely Oxyopes salticus, Dermaptera, Holcocephala sp., Rainieria sp., Orius insidiosus, Dolichoderus sp., Paratrechina sp., Oecophylla sp. and Conocephalus longipennis. At the individual paraistoid level, Apanteles sp. became the most common, followed by the predatory fly Holcocephala sp. and ants Dolichoderus sp., fly Rainieria sp., ladybug Orius insidiosus, Dermaptera, ant Paratrechina sp., ant Oecophylla sp. and the grasshopper Conocephalus longipennis.

Insecticidal capacity of polyphenolic seed compounds from neem (Azadirachta indica) on Spodoptera frugiperda (J. E. Smith) larvae

The objective of this study was to evaluate the insecticidal activity of the polyphenolic compounds found in neem on S. frugiperda larvae. Three neem extracts (1:12 (m/v) with 70% ethanol, 1:12 (m/v) with 0% ethanol (only water), and 1:4 (m/v) with 0% ethanol) were employed. Subsequently, the extraction of phytochemical compounds of each extract was performed using ultrasound and microwave technologies simultaneously. The compound characterization was performed by HPLC-mass. In addition, the insecticidal evaluation of the neem extract was performed against S. frugiperda of the second-stage larvae. The extracts were applied by spraying the larvae according to each bioassay. Results showed that the extract obtained with a 1:12 (m/v) relationship and 70% ethanol was effective for the control of S. frugiperda larvae. In this extract, the predominant organic compound families were: methoxyflavones, flavonols, hydroxycoumarins, anthocyanins, methoxycinnamic acid, and alkylflavones. Phytochemical compounds obtained from neem seeds with environmentally friendly solvents and alternative technologies (ultrasound and microwave) have potent insecticidal activity against S. frugiperda larvae.

Beneficial rhizobacteria inoculation on Ocimum basilicum reduces the growth performance and nutritional value of Spodoptera frugiperda.

Plant growth-promoting rhizobacteria (PGPR) has a significant role in plant-insect interaction. However, the extent of their impact on insects is still not well understood. This investigation was designed to evaluate the role of inoculation with Bacillus amyloliquefaciens GB03 on sweet basil (Ocimum basilucum L.) in the development and nutritional parameters of Spodoptera frugiperda. In addition, the feeding preferences on inoculated and non-inoculated plants were assessed. Spodoptera frugiperda larvae reared with inoculated sweet basil leaves had a strong negative effect on the development of the insect, resulting in lower larval and pupal weights, and a longer period for larval-adult development. Moreover, adult emergence was reduced, but the relative consumption rate (RCR) value was unaffected, thereby revealing no alteration of the palatability. Growth rate and nutritional indicators, such as the efficiency of conversion of ingested food (ECI) and the efficiency of conversion of digested food (ECD), were reduced in larvae reared from treated plants. In the choice test, larvae avoided feeding on inoculated leaves. The higher occurrence of secondary metabolites in inoculated plants could have been the reason for the reduction of the plant nutritional rate and also for the food selection, since it has been previously reported that GB03 inoculated sweet basil increased the essential oil yield. Therefore, PGPR inoculation could be used as a growth promoter, making it a promising candidate for plant protection programs against insects in aromatic plant production. © 2021 Society of Chemical Industry.

Whole Genome Sequencing Analysis of Bacillus thuringiensis GR007 Reveals Multiple Pesticidal Protein Genes.

Bacillus thuringiensis (Bt) are soil ubiquitous bacteria. They produce a great variability of insecticidal proteins, where certain of these toxins are used worldwide for pest control. Through their adaptation to diverse ecosystems, certain Bt strains have acquired genetic mobile elements by horizontal transfer, harboring genes that encode for different virulent factors and pesticidal proteins (PP). Genomic characterization of Bt strains provides a valuable source of PP with potential biotechnological applications for pest control. In this work, we have sequenced the complete genome of the bacterium Bt GR007 strain that is toxic to Spodoptera frugiperda and Manduca sexta larvae. Four replicons (one circular chromosome and three megaplasmids) were identified. The two largest megaplasmids (pGR340 and pGR157) contain multiple genes that codify for pesticidal proteins: 10 cry genes (cry1Ab, cry1Bb, cry1Da, cry1Fb, cry1Hb, cry1Id, cry1Ja, cry1Ka, cry1Nb, and cry2Ad), two vip genes (vip3Af and vip3Ag), two binary toxin genes (vpa2Ac and vpb1Ca), five genes that codify for insecticidal toxin components (Tc’s), and a truncated cry1Bd-like gene. In addition, genes that codify for several virulent factors were also found in this strain. Proteomic analysis of the parasporal crystals of GR007 revealed that they are composed of eight Cry proteins. Further cloning of these genes for their individual expression in Bt acrystalliferous strain, by means of their own intrinsic promoter showed expression of seven Cry proteins. These proteins display differential toxicity against M. sexta and S. frugiperda larvae, where Cry1Bb showed to be the most active protein against S. frugiperda larvae and Cry1Ka the most active protein against M. sexta larvae.

English

Since chemical insecticides favor the emergence of resistance and have disastrous consequences for the environment, we became interested in an alternative control method against Spodoptera frugiperda, more respectful for the environment. We therefore evaluated the effectiveness of the bio-insecticidal effects of plants extracts and oil of castor against the fall armyworm in the laboratory. The laboratory bioassays consisted of evaluating the toxicity of the castor plants extracts and oil by contact and ingestion on fourth instar larvae of Spodoptera frugiperda using a leaf dipping method. It emerges from this study that the mortality of the larvae treated with the bio-insecticide and the control solution varies significantly and that the mortality rate was 100% for dose 1; 85% for dose 2 and 70% for dose 3. The mortality rate for the control solution is 10%. These results testify to the good larvicidal activity of the organic insecticide based on oil, leaves and unripe seeds of castor bean on the fall armyworm.

Effect of extract of Amazon Moss on Spodoptera Frugiperda (JE Smith) (Lepidoptera: noctuidae) in maize

Bryophytes are a potential group for the discovery of biologically active substances to pest control. The objective of this study was to evaluate the antifeedant and insecticidal effect of the ethanolic extract of Sematophyllum subsimplex (Hedw). Mitt. on second-instar larvae of Spodoptera frugiperda (JE Smith, 1797) on corn (Zea mays L.) leaves. The bioassay involved placing individual larvae in petri dishes and fed circular corn leaf sections with 50 µl of the extract at concentrations of 2.0%, 1.0%, 0.5% and 0.25% µg/µl, and DMSO (control), with five replicates, in no-choice feeding assays. Herbivory and mortality rates were assessed 24, 48 and 72 hours after application of the extract. The concentration of 0.25 μg/μl had a positive antifeedant effect shortly after 24 hours. All tested concentrations caused high mortality rates, suggesting insecticidal activity. This is the first scientific work to report the antifeedant and/or insecticidal activity of S. subsimplex and can be the basis for botanical insecticide formulation.

Isolation and structural identification of insecticidal compounds from Tripterygium wilfordii

Five compounds were identified from Tripterygium wilfordii, including two novel compounds and three previously known compounds. Two newly discovered compounds are celangulin CY (1α,2α,3β,4β,6β,8α,13-hepacetoxy-9β-benzoyloxy-β-dihydroagarofuran) and celangulin CQ (1α-nicotinoyloxy-2α,3β,6β-triacetoxy-9β-furancarbonyloxy-13-isobutanoyloxy-4β-hydroxy-β-dihydroagarofuran). Their structures were determined using nuclear magnetic resonance (NMR), mass spectrometry (MS), and high-pressure liquid chromatography (HPLC). The isolated compounds were tested for insecticidal activity against the third instar larvae of Spodoptera frugiperda. Both celangulin CY and celangulin CQ exhibited significantly higher oral toxicity in the larvae than that exhibited by the three known compounds.

Bis- and mono-substituted Chalcones exert anti-feedant and toxic effects on fall armyworm Spodoptera frugiperda

Spodoptera frugiperda is a highly polyphagous migratory lepidopteran pest species. It causes infestation in crops leading to the severe crop losses. Being a new invasive parasite, its susceptibility to insecticides needs to be explored; and therefore, there is an urgent need to develop the potent insecticides for the effective control of this insect pest. To attain the crop sustainability, the antifeedant, toxicity and nutritional effects on larvae of Spodoptera frugiperda were studied with six mono- and eight bis- substituted chalcones. The antifeedant activity was calculated when 50% of the larvae control ate 50% of the diet through the FR factor. Toxicity was assessed through larval, pupal mortality and the emergence of adults and nutritional effects with consumption rates (IC), growth (GR) and consumption efficiency (EIC). The bis-chalcones 6b, 6e, 6f and 6h caused lethal effect on S. frugiperda in the first larval stages, being 6b the most toxic (85%). Adults who survived showed malformations and decreased size, which led to death. The larvae fed with aggregate in the bis-chalcones diet: 6b, 6e and 6f had the highest percentage of intake and the poorest conversion of nutrient absorption (ECI), which suggests that the larva metabolizes food for energy and results in a decrease of growth and death in early stages. Bis-chalcones showed more toxicity than mono-chalcones and 6b causes the most toxic and dietary change.