Antifeedant Activity Research Articles

In Silico Analysis of Limonoid-Based Antifeedants from Melia volkensii Targeting the Ryanodine Receptor in Spodoptera frugiperda

Spodoptera frugiperda is an invasive pest causing significant crop losses worldwide. Resistance development and health and environmental concerns associated with synthetic insecticides have prompted a search for eco-friendly biopesticides. Limonoids such as salannin, volkensin, and volkensinone, isolated from the East African plant Melia volkensii, show antifeedant activity against S. frugiperda larvae. Volkensin had an ED50 of 3.5 µg/cm², volkensinone (a lactone of volkensin) an ED50 of 6 µg/cm², and salannin an ED50 of 13 µg/cm². Additional limonoids from M. volkensii, including salanninolide and toosendanin, also displayed strong antifeedant effects. With toosendanin already used commercially, a re-evaluation of M. volkensii antifeedant compounds was conducted using in silico techniques. Docking simulations with 3D models of these limonoids and the S. frugiperda ryanodine receptor protein revealed binding affinities from -6.4 to -7.5 kcal/mol, comparable to those of chlorantraniliprole, a commercial insecticide targeting ryanodine receptors. These binding affinities at two distinct receptor sites align well with in-vitro antifeedant activity, underscoring M. volkensii’s potential for environmentally friendly, receptor-targeted biopesticide development against S. frugiperda.

Antifeedant Nanosuspension Formula of <i>Tithonia diversifolia</i> Leaf Extract by Emulsion Inverse Method to Control <i>Crocidolomia pavonana</i> Cabbage Pest Insect

The leaf extract from Tithonia diversifolia is recognized for its ability to deter feeding in various Lepidoptera insect pests, including the larvae of Crocidolomia pavonana. Presently, transformation efforts from conventional formulations into nano-based formulations for biopesticides exhibit enhanced effectiveness and efficiency. Utilizing a low-energy process, an inversion emulsion facilitates the dispersion of the extract suspension in an organic solvent into a water-immiscible solvent using a suitable surfactant. The forming nano-size droplets in water (t1, t2, t3, t4) are influenced by the ratio of surfactant and organic suspension (Water: Tween 80: Organic suspension). The emulsification method successfully formulated T. diversifolia leaf extract, into dispersed nano-size and submicron suspensions in water. The t3 formula exhibits the smallest nano-size dispersed in water (D=23.6 ± 39.6 nm; polydispersity index IP=0.702) and enhanced wettability, evident in the lower contact angle of the droplet on the cabbage leaf surface (49.4°) compare with the control group. The Phytochemicals confirmed by IR-spectra analysis identified the phenols, alkaloids, and steroids constituents of leaf extract, which are known to have antifeedant properties. The enhanced antifeedant properties of T. diversifolia nanosuspension against C. pavonana third-instar larvae demonstrated by the antifeedant test results showing that t3 is the most successful deterrent larvae feeding activity compared to the control (P<0.05), due to the highest total antifeedant coefficient (74.27%) in a category medium antifeedant activity, while the non-emulsification displayed the lowest antifeedant coefficient (25.36%) in a category as low antifeedant activity. T. diversifolia leaf extract with a nano-based formula succeeded resulting in dispersed nano-size and submicron suspension in aqueous media, thereby reducing surface tension and enhancing wettability on the leaf surface during application. The improved dispersion of antifeedant nanosuspension on the leaf surface results in more effective delivery to target insects.

Isolation of Natural Veratrylidenehydrazide Compound from Wedelia Biflora and Synthesis of Veratrylidenehydrazide Analogue: Investigation of Larvicidal Activity Against Culex Quinquefasciatus and Toxicity Analysis in Nontarget Aquatic Species

AbstractIn this study, veratrylidenehydrazide was isolated from Wedelia biflora, and compounds (1a, 2a, and 3a–j) were synthesised to evaluate their larvicidal and antifeedant activities. Veratrylidenehydrazide 1a was verified using GC‐MS. The veratrylidenehydrazide analogues 2a and 3a–j were synthesised via a condensation method with yield range 71%–92%. The compounds (1a, 2a, and 3a–j) were synthesised and characterised through FT–IR, 1H NMR, 13C NMR, mass spectrometry, and elemental analysis. Veratrylidenehydrazide 1a was verified using GC‐MS analysis. Natural veratrylidenehydrazide compound 1a and the synthesised veratrylidenehydrazide analogues (2a, 3a–j) were screened for larvicidal activity against Culex quinquefasciatus. The larvicidal activity of compound 3g was found to be highly active, while low toxicity was observed against Oreochromis mossambicus nontarget aquatic species compared to natural veratrylidenehydrazide. Compound 3g exhibited a higher binding affinity (−8.8 kcal/mol) compared to standard of temephos (−4.5 kcal/mol), equipotential binding affinity against permethrin (−9.1 kcal/mol), and diflubenzuron (−8.5 kcal/mol). Lead molecules have larvicidal properties, and their use as insecticides makes them important.

A new Bowman-Birk type protease inhibitor regulated by MeJA pathway in maize exhibits anti-feedant activity against the Ostrinia furnacalis.

Jasmonic acid (JA), an important plant hormone, plays a crucial role in defending against herbivorous insects. In this study, we have identified a new Bowman-Birk type protease inhibitor (BBTI) protein in maize that is regulated by the JA pathway and exhibits significant antifeedant activity, which is notably induced by exogenous Methyl Jasmonate and Ostrinia furnacalis feeding treatments. Bioinformatics analysis revealed significant differences in the BBTI protein among different maize inbred lines, except for the conserved domain. Prokaryotic and eukaryotic expression systems were constructed and expressed, and combined with bioassays, it was demonstrated that the antifeedant activity of BBTI is determined by protein modifications and conserved domains. Through RT-qPCR detection of BBTI and JA regulatory pathway-related genes' temporal expression in different maize inbred lines, we identified the regulatory mechanism of BBTI synthesis under the JA pathway. This study successfully cloned and identified the MeJA-induced anti-feedant activity gene BBTI and conducted functional validation in different maize inbred lines, providing valuable insights into the response mechanism of insect resistance induced by the plant JA pathway. The increased expression of the anti-feedant activity gene BBTI through exogenous MeJA induction may offer a potential new strategy for mediating plant defense against Lepidoptan insects.

Nematicidal and Insecticidal Compounds from the Laurel Forest Endophytic Fungus Phyllosticta sp.

The search for natural product-based biopesticides from endophytic fungi is an effective tool to find new solutions. In this study, we studied a pre-selected fungal endophyte, isolate YCC4, from the paleoendemism Persea indica, along with compounds present in the extract and the identification of the insect antifeedant and nematicidal ones. The endophyte YCC4 was identified as Phyllosticta sp. by molecular analysis. The insect antifeedant activity was tested by choice bioassays against Spodoptera littoralis, Myzus persicae, and Rhopalosiphum padi, and the in vitro and in vivo mortality was tested against the root-knot nematode Meloidogyne javanica. Since the extract was an effective insect antifeedant, a strong nematicidal, and lacked phytotoxicity on tomato plants, a comprehensive chemical study was carried out. Two new metabolites, metguignardic acid (4) and (-)-epi-guignardone I (14), were identified along the known dioxolanones guignardic acid (1), ethyl guignardate (3), guignardianones A (5), C (2), D (7), and E (6), phenguignardic acid methyl ester (8), the meroterpenes guignardone A (9) and B (10), guignarenone B (11) and C (12), (-)-guignardone I (13), and phyllomeroterpenoid B (15). Among these compounds, 1 and 4 were effective antifeedants against S. littoralis and M. persicae, while 2 was only active on the aphid M. persicae. The nematicidal compounds were 4, 7, and 8. This is the first report on the insect antifeedant or nematicidal effects of these dioxolanone-type compounds. Since the insect antifeedant and nematicidal activity of the Phyllosticta sp. extract depend on the presence of dioxolanone components, future fermentation optimizations are needed to promote the biosynthesis of these compounds instead of meroterpenes.

Cu(II)-tyrosinase enzyme catalyst mediated synthesis of mosquito larvicidal active pyrazolidine-3,5-dione derivatives with molecular docking studies and their ichthyotoxicity analysis

The objective of this study was to develop pyrazolidine-3,5-dione derivatives with potential as environmentally friendly pesticides for pest control, specifically focusing on their efficacy as larvicidal agents. A novel one-pot synthesis of multicomponent pyrazolidine-3,5-dione derivatives (1a-m) was accomplished via the grindstone method using Cu(II)tyrosinase enzyme as a catalyst under mild reaction conditions, yielding 84%–96%. The synthesised derivatives (1a-m) were characterized using various spectroscopic methods (mass spectrometry, elemental analysis, FT-IR, and 1H and 13C NMR). NMR characterisation using DMSO-d6 as a solvent. The larvicidal and antifeedant activities of the synthesised compounds were screened and in silico computational studies were performed. The larvicidal activity against Culex quinquefasciatus and antifeedant activity against Oreochromis mossambicus were evaluated. Among the synthesised compounds, compound 1c demonstrated superior efficacy (LD50: 9.7 μg/mL) against C. quinquefasciatus compared to permethrin (LD50: 17.1 μg/mL). Regarding antifeedant activity, compounds 1a, 1e, 1f, 1j, and 1k exhibited 100% mortality at 100 μg/mL. Molecular docking analysis was performed to assess the binding capacity of a mosquito odorant-binding protein (3OGN) from Culex quinquefasciatus to compound 1c. The results revealed that compound 1c had a docking score of -10.4 kcal/mol, surpassing that of standard permethrin (-9.5 kcal/mol). Furthermore, DFT calculations were conducted to acquire theoretical data aligned with the experimental FT-IR results. According to experimental research, compound 1c demonstrates promising larvicidal activity against mosquito larvae of C. quinquefasciatus.

Repellency, Fumigant Toxicity, Antifeedent and Residual Activities of Coridothymus capitatus and Its Main Component Carvacrol against Red Flour Beetle.

Tribolium castaneum is a challenging pest of stored products, causing significant economic losses. The present study explored the efficacy of Coridothymus capitatus essential oil and its primary constituent, carvacrol, as eco-friendly alternatives for managing this pest. To evaluate their insecticidal potential, repellency, fumigant toxicity, and antifeedant properties, progeny inhibition assays were performed. Carvacrol exhibited superior repellency compared to the essential oil, achieving a 92% repellency rate at 2 mg/cm2. Both compounds demonstrated significant fumigant toxicity against T. castaneum, with LC50 values of 168.47 and 106.5 μL/L for the essential oil and carvacrol, respectively, after 24 h. Carvacrol also outperformed the essential oil in antifeedant activity, inducing an 80.7% feeding deterrence at 1.17 mg/g. Moreover, both treatments effectively suppressed the development of the pest's progeny. These results collectively underscore the potent insecticidal properties of C. capitatus essential oil and carvacrol, particularly carvacrol, as promising candidates for the sustainable management of T. castaneum in stored product protection.

Insecticidal and Anti-Feedant Activity of Clerodendrum Extracts on Growth and Development of Castor Spiny Caterpillar, Ariadne merione

The castor spiny caterpillar Ariadne merione (F.) is a major lepidopteran pest affecting castor (Ricinus communis) crops mainly by causing defoliation which in turn reduces the photosynthesis and yield. The conventional pest control methods have been based on chemical control which although has been effective, has its drawbacks of being hazardous to the environment and human health besides leading to resistance by the pests. The present work aims at investigating the possibility of using Clerodendrum inerme, a plant belonging to the Lamiaceae family, as an eco-friendly solution for pest management. Insecticidal and anti-feedant efficacy of C. inerme leaf extracts, which were prepared using solvents hexane, acetone, and petroleum ether, was tested against A. merione larvae using leaf dip bioassay under no-choice situation. The findings showed that the hexane extract had the highest insecticidal (73%) and anti-feedent (97%) action. The petroleum ether extract also showed moderate insecticidal (50%) and anti-feedant activity (48%) but not as potent as the acetone extract having insecticidal and anti-feedant action of 60 and 74 per cent respectively. The results imply that C. inerme extracts, especially the hexane extract, could be used as botanical insecticides in IPM programs as a natural replacement for chemical insecticides.

Design, Synthesis, and Antifeedant Activity Evaluation of 13/14-Arylthioether Matrine Derivatives.

Introducing a sulfur atom into active agricultural molecules is an important strategy for pesticide development. Matrine, an environmentally friendly botanical pesticide, has the advantage of being easily degraded and has drawn attention in the agricultural field. To explore the novel matrine-type pesticides, in this study, we designed and synthesized 13/14-arylthioether matrine derivatives by introducing various aryl sulfide motifs into bioactive matrine. Most of the synthesized arylthioether matrines exhibited good antifeedant activity against Spodoptera exigua. Among them, compound 2q showed the best antifeedant effect with an EC50 value of 0.038 mg/mL, which is approximately 125-fold more activity than matrine and reached the activity level of commercial standard azadirachtin A. Furthermore, compound 2q exhibited an inhibitory effect on antifeedant-related enzyme carboxylesterase (CarE) from S. exigua. In short, the high activity of arylthioether matrines offers new insights into developing new antifeedants.

Antifeedant and growth inhibitory effects of extracts from Ajania potaninii and A. fruticulosa against Tribolium castaneum (Coleoptera: Tenebrionidae)

This study aimed to evaluate the nutritional and antifeedant indices of Tribolium castaneum in response to the compounds and main chemical constituents ofAjania potaninii and A. fruticulosa. These mainly includes essential oils and their major ingredients (eucalyptol, camphor, myrtenol, verbenol, and borneol), as well as nonvolatile compounds. The A. fruticulosa and A. potaninii EOs exhibited clear antifeedant activity against T. castaneum adults at a 2 mg/L concentration, with FDI of 50% and 60%, respectively. Among the nonvolatile compounds, sesamin and eriodictyol exhibit strong antifeedant activities against T. castaneum adults at the same concentration, with an FDI of 90.57% and 88.68% after 72 h, respectively. For larvae, A. fruticulosa and A. potaninii EOs also resulted in antifeedant activity (respective FDI: 57.08% and 55.63%). In addition, sesamin and eriodictyol had exceptionally potent antifeedant activity against T. castaneum larvae, with FDI values 90.71% and 96.17%, respectively. In nutritional studies, the reductions in relative food consumption rate (RCR) of T. castaneum were more pronounced for 1 mg/L and 2 mg/L of either eucalyptol or sesamin. However, at greater concentrations, the conversion efficiency of eucalyptol and sesamin to ingested food in T. castaneum was significantly improved. Eucalyptol and sesamin showed a dose-dependent FDI for this insect. Considering the significant anti-insect activities, the EOs, main compounds, and non-volatile compounds of both A. potaninii and A. fruticulosa might be useful in devising integrated pest strategies, providing a promising perspective for the comprehensive use of natural plant resources from the Ajania genus.

Synthesis and antifeedant activity of 3H-indole derived oxime esters and oxime ethers against cotton bollworm

The O-acylation or O-alkylation of 3H-indole derived oximes is conveniently synthesized from indoles and the corresponding anhydrides or alcohols mediated by tert-butyl nitrite (TBN) under mild conditions. O-Acyloxime esters are obtained with yields up to 82% using anhydrides via a facile one-pot reaction. Fluorinated O-alkyloxime ethers are achieved with yields up to 38% using fluorinated alcohols through an optimized step-by-step strategy or a 2,2,6,6-tetramethylpiperidinyl-1-oxide (TEMPO)-assisted one-pot strategy. Meanwhile, the better reaction yields, up to 64%, are achieved for nonfluorinated O-alkyloxime ethers. These approaches allow access to a diversity of O-acyloxime esters and fluorinated/nonfluorinated O-alkyloxime ethers, underscoring broad substrate scopes, good functional tolerance and easily gram-scale. All the synthesized compounds were evaluated for their potential antifeedant activity and 5f shows good antifeedant activity against cotton bollworm with a negative logarithmic effective concentration for 50% feeding reduction (pEC50) at 4.217.

Antifeedant Activity of Selected Botanicals Against the Larvae of Helicoverpa armigera (Hubner)

Antifeedant Activity of Selected Botanicals Against the Larvae of Helicoverpa armigera (Hubner)

Biopesticidal Potential of Lippia javanica (Burm. F) Spreng. Leaf Extracts and their Fractions against Spodoptera litura (Fab.)

Three organic solvent extracts of Lippia javanica leaves were screened for their antifeedant and larvicidal activities against the 4th instar larvae of Spodoptera litura at 5% concentration. The maximum antifeedant and larvicidal activities were recorded in ethyl acetate extract (76.57%) for antifeedant and (90.40%) for larvicidal activity, followed by chloroform and hexane extracts. Ten fractions were obtained from the ethyl acetate extract of L. javanica by using different combinations of hexane and ethyl acetate as the mobile phase through column chromatography. The fractions were screened at 1000 ppm concentrations for antifeedant and larvicidal activities. Fraction 10 (71.75%) was found to be the most effective one, followed by fraction 4 (61.32%) and fraction 7 (60.58%) for antifeedant acitivity. At a 1000 ppm concentration, fraction 3 exhibited the highest larvicidal activity (79.20%) against S. litura, followed by fraction 1 (76.0%), while fractions 5 and 6 have shown equal activity. Quantitative protein analysis revealed that treatment with the eighth fraction reduced the haemolymph protein drastically (1.52 mg/mL) compared to control (2.84 mg/mL) and other fractions. In the reference control azadirachtin treatment, the haemolymph protein quantity was found to be nearly the same (1.4 mg/mL) as that of the eighth fraction. Treatment with the first and second fractions resulted in increased haemolymph protein (8 and 7.6 mg/mL, respectively). The bio-efficacy of L. javanica in pest management is discussed.

Insecticidal Triterpenes in Meliaceae III: Plant Species, Molecules, and Activities in Munronia-Xylocarpus.

Plants of the Meliaceae family have long attracted researchers' interest due to their various insecticidal activities, with triterpenes being the main active ingredients. In this paper, we discuss 93 triterpenoids with insecticidal activity from 37 insecticidal plant species of 15 genera (Munronia, Neobeguea, Pseudocedrela, Nymania, Quivisia, Ruagea, Dysoxylum, Soymida, Lansium, Sandoricum, Walsura, Trichilia, Swietenia, Turraea, and Xylocarpus) in the family Meliaceae. Among these genera, Trichilia deserves further research, with twelve species possessing insecticidal activity. The 93 insecticidal molecules included 27 ring-seco limonoids (comprising 1 ring A-seco group chemical, 1 ring B-seco group chemical, 5 ring D-seco group chemicals, 14 rings A,B-seco group chemicals, 5 rings B,D-seco group chemicals, and 1 rings A,B,D-seco group chemical), 22 ring-intact limonoids (comprising 5 cedrelone-class chemicals, 6 trichilin-class chemicals, 7 havanensin-class chemicals, 2 azadirone-class chemicals, 1 vilasinin-class chemical, and 1 other chemical), 33 2,30-linkage chemicals (comprising 25 mexicanolide-class chemicals and 8 phragmalin-class chemicals), 3 1,n-linkage-group chemicals, 3 onoceranoid-type triterpenoids, 2 apotirucallane-type terpenoids, 2 kokosanolide-type tetranortriterpenoids, and 1 cycloartane triterpene. In particular, 59 molecules showed antifeedant activity, 30 molecules exhibited poisonous effects, and 9 molecules possessed growth regulatory activity. Particularly, khayasin, beddomei lactone, 3β,24,25-trihydroxycycloartane, humilinolides A-E and methyl-2-hydroxy-3β-isobutyroxy-1-oxomeliac-8(30)-enate showed excellent insecticidal activities, which were comparable to that of azadirachtin and thus deserved more attention. Moreover, it was noteworthy that various chemicals (such as 12α-diacetoxywalsuranolide, 11β,12α-diacetoxycedrelone, 1α,7α,12α-triacetoxy-4α-carbomethoxy-11β-hydroxy-14β,15β-epoxyhavanensin, and 11-epi-21-hydroxytoonacilide, etc.) from Turraea showed excellent insecticidal activity. Specially, the insecticidal activity of khayasin from Neobeguea against the coconut leaf beetle were similar to that of rotenone. Therefore, it was a promising candidate insecticide for the control of the coconut leaf beetle.

Four New Furofuran Lignans from Phryma leptostachya Inhibit the Accumulation of Molting Hormones in Armyworm.

Furofuran lignans have been identified as the main substances responsible for the biological activities of the plant genus Phryma. Here, four new phrymarolin-type leptolignans A-D (7-10) and eight previously known lignans were isolated from P. leptostachya. Of these, nine exhibited significant antifeedant activity against armyworm (Mythimna separata) through a dual-choice bioassay, with the EC50 values ranging from 0.58 to 10.08 μg/cm2. In particular, the newly identified lignan leptolignan A (7) showed strong antifeedant activity, with an EC50 value of 0.58 ± 0.34 μg/cm2. Further investigation found that leptolignan A can inhibit the growth and nutritional indicators in the armyworm M. separata. The concentrations of two molting hormones, 20-hydroxyecdysone and ecdysone, were also found to decrease significantly following the treatment of the armyworms with the lignan, implying that the target of the P. leptostachya lignan may be involved in 20-hydroxyecdysone and ecdysone synthesis. These results enrich our knowledge of P. leptostachya metabolite structural diversity, and provide a theoretical basis for the control of armyworm using lignans.

Nematicidal and insecticidal activity of essential oils from Artemisia scoparia and Centratherum punctatum and their mixtures

The present study involves the phytochemical analysis and assessing potential synergies among essential oils (EOs) against pests. The EOs were obtained by hydrodistillation from the aerial part (ASAO) and the root part (ASRO) of Artimisia scoparia, and from the aerial part of Centratherum punctatum (CPAO). The EOs yield ranged from 0.5 to 0.1% (v/w). The GC-MS analysis revealed the presence of 35, 43, and 49 compounds, constituting 99.2%, 98.34%, and 99.93% in ASAO, ASRO, and CPAO, respectively. Capillene was identified as the dominant compound both in ASAO and ASRO, but in variable amounts. Caryophyllene oxide (36.4%) was identified as the major component of CPAO. Pure EOs were blended in binary and ternary mixtures at ratios to analyze their synergistic effect against pests. The nematicidal activity (percent mortality and egg hatchability against Meloidogyne incognita at different concentrations was evaluated and the ternary mixture (ASAO + ASRO + CPAO) was found to be most effective at 1 μL/mL with 55.67 ± 1.41% larval immobility at 96 h of exposure. The antifeedant activity of pure and blended EOs was examined against Spodoptera litura using the leaf-dip method. Individually ASAO was most effective with 66.91% feeding inhibition, however the ternary combination showed 58.03% feeding inhibition. Moreover, molecular docking of selected volatiles (≥4% area) from the tested samples was carried out to analyze the interactions with target protein; acetylcholinesterase (AChE) and glutathione S-transferases (GST-1) and the ligands interacted favourably with the target proteins. The blending of EOs resulted in synergistic effects, enhancing their efficacy. Data acquired highlighted that A. scoparia and C. punctatum essential oils could be natural alternatives for nematode control and pest control in agriculture.

Bio-efficacy of mustard seed extracts against Bihar hairy caterpillar Spilosoma obliqua (Erebidae: Lepidoptera) & assessment of mustard allelo-chemicals in response to mustard aphid Lipaphis erysimi (Aphididae: Hemiptera) infestation

Mustard seed contains glucosinolate-myrosinase system of substrate-enzyme metabolism, accompanied with compartmentalized cells. Upon rupture, enzyme myrosinase leads to breakdown of glucosinolates and its metabolized products like allyl, benzyl, phenyl type of isothiocyantes and many other types like nitriles are released. The myrosinase activity is tested in three globally utilized different seed coat color mustards viz., brown mustard (Brassica juncea), white mustard (Sinapis alba) and black mustard (Brassica nigra) to demonstrate the release of glucosinolates which are known to deter insect pests. Aqueous seed extracts of these mustard types were subjected to anti-feedant activity analysis and oil extracted from these mustard seeds was subjected to insecticidal activity analysis against Spilosoma obliqua 4th instars on castor leaves. Meanwhile, the mustard leaves in open field were allowed for natural aphid infestation during early months from January to March. Thereafter, the leaf twigs of white, black and brown mustard, infested and uninfested by aphids, were collected and myrosinase activity of plants was analyzed with varying levels of important pest inflicted biochemicals in plant, viz., Total phenols, ortho-dihydric phenols and flavonols. Gas Chromatography–Mass Spectrometry analysis of mustard oil used in insecticidal activity was performed to elucidate the role of biochemicals involved in action. These compounds along with fatty acids and sterols compounds are known to have anti-feedant & insecticidal activities. Aqueous extract components were also subjected to total glucosinolate analysis, spectrophotometrically for knowing their concentration, with highest in brown (85.81 µmol/g) followed by black (59.32 µmol/g) and lowest in white mustard (47.63 µmol/g). The amount of glucosinolates, free fatty acids & sterol compounds present in different coat color mustard seed types are being correlated here with their potential bioactivities against biological plant pests. Bio-control of potentially harmful insect pests is possible by utilizing anti-feeding & insecticidal potential of mustard seed extracts.

Antifeedant, antifungal and nematicidal compounds from the endophyte Stemphylium solani isolated from wormwood

The continuous search for natural product-based biopesticides from fungi isolated from untapped sources is an effective tool. In this study, we studied a pre-selected fungal endophyte, isolate Aa22, from the medicinal plant Artemisia absinthium, along with the antifungal, insect antifeedant and nematicidal compounds present in the extract. The endophyte Aa22 was identified as Stemphylium solani by molecular analysis. The antifungal activity was tested by broth microdilution against Fusarium solani, F. oxysporum, F. moniliforme and Botrytis cinerea, the insect antifeedant by choice bioassays against Spodoptera littoralis, Myzus persicae and Rhopalosiphum padi and the in vitro mortality against the root-knot nematode Meloiydogyne javanica. The structures of bioactive compounds were determined on the basis of 1D and 2D NMR spectroscopy and mass spectrometry. The ethyl acetate extract obtained from the solid rice fermentation showed mycelial growth inhibition of fungal pathogens (EC50 0.08–0.31 mg/mL), was antifeedant to M. persicae (99%) and nematicidal (68% mortality). A bioguided fractionation led to the isolation of the new compound stempholone A (1), and the known stempholone B (2) and stemphol (3). These compounds exhibited antifeedant (EC50 0.50 mg/mL), antifungal (EC50 0.02–0.43 mg/L) and nematicidal (MLD 0.5 mg/mL) activities. The extract activities can be explained by 3 (antifungal), 1–3 (antifeedant) and 1 (nematicidal). Phytotoxicity tests on Lolium perenne and Lactuca sativa showed that the extract and 1 increased L. sativa root growth (121–130%) and 1 reduced L. perenne growth (48–49%). These results highlight the potential of the endophytic fungi Aa22 as biotechnological source of natural product-based biopesticides.

NANOPARTÍCULAS METÁLICAS POR SÍNTESIS VERDE Y SU APLICACIÓN COMO INSECTICIDAS

<p><strong>Background:</strong> The synthesis of nanoparticles from living organisms better known as biological synthesis or green synthesis has become a potential tool due to the advantages it provides compared to other existing synthesis methods. Green synthesis is presented as an environmentally friendly, safe, less toxic and cost-effective alternative. Due to these properties green nanoparticles have been implemented in the field of agriculture, mainly as nanopesticides. <strong>Objective:</strong> To review the reports on the evaluation of green nanoparticles against insects, as well as the knowledge on the possible modes of action of these nanoparticles. <strong>Methodology:</strong> A compilation of scientific information was made in different search engines, from which those that evaluated nanoparticles by green synthesis as insecticides were selected. <strong>Results:</strong> Among the modes of action caused by metallic nanoparticles, the following stand out: damage and histological changes at intestinal level, antifeedant activity, physical damage to the cuticle, decreased cell viability and inhibition of fecundity. <strong>Implications:</strong> the availability of information on nanoparticles is fundamental to be able to scientifically propose their implementation in insect pest management strategies. <strong>Conclusion:</strong> green synthesis of nanoparticles is presented as an alternative to produce nanoinsecticides; however, further research is needed on the mechanisms of action on insects, as well as their long-term repercussions on human and environmental health.</p>

Assessment of the Phytotoxicity and Antifeedant Properties of Aristolochia bracteolata Lamk. Leaf Extracts and their Derivatives against the Spotted Bollworm, [Eariasvittella (Fab.)], (Lepidoptera: Noctuidae)

The phytopesticidal effects of various solvent crude extracts and isolated fractions from the leaves of Aristolochia bracteolata, which were tested for their antifeedant and larvicidal activities on the fourth instar larvae of the shoot and fruit of Earias vittella.The antifeedant and larvicidal activities were performed by fruit disc no-choice methods at 0.625, 1.25, 2.5, and 5% and 125, 250, 500, and 1,000 ppm concentrations for crude and fractions, respectively. The dichloromethane (DCM) extract of A. bracteolata exhibited the maximum antifeedant (61.10%) and larvicidal (65.33%) activities at 5% concentration against E. vittella, followed by hexane (44.93%), acetone (40.40%) and aqueous (22.25%) extracts. It was subjected to fractionation using silica gel column chromatography with different combinations of hexane and ethyl acetate used as the mobile phase. Among the six fractions obtained, fraction 6 showed the maximum antifeedant (78.32%) and larvicidal (81.77%) activities against E. vittella at a 1000 ppm concentration. The preliminary phytochemical analysis of the plant also showed alkaloids, anthroquinones, diterpenoids, flavonoids, glycosides, polyphenols, saponins, steroids, and tannins in the extract. A. bracteolata leaves could be complemented with an eco-friendly pesticide/insecticide for an integrated pest management strategy.