Emamectin Research Articles

Design and Synthesis of a Water-Based Nanodelivery Pesticide System for Improved Efficacy and Safety.

Developing an environmentally friendly and safe nanodelivery system is crucial to improve the efficacy of pesticides and minimize environmental and health risks. However, preparing a completely water-based nanopesticide without using harmful solvents is a technical challenge. In this study, a water-based nanodelivery pesticide system was constructed to improve the efficacy and safety of Emamectin Benzoate (EB). A specific surfactant, 29-(4-(5-hydroxynonan-5-yl)phenoxy)-3,6,9,12,15,18,21,24,27-nonaoxanonacosan-1-ol (SurEB) was designed and synthesized to form a water-based nanodelivery system (EBWNS) with EB. Molecular dynamics simulations revealed the self-assembly and interaction forces between SurEB and EB in water, providing insights into the formation mechanism of EBWNS nanoparticles. The nanodelivery system showed the prolonged effectivity of EB with reduced degradation and demonstrated a good control efficacy for multiple target pests, such as red spider mite, beet armyworm larvae (Lepidoptera: Noctuidae), and rice stem borers (Chilo suppressalis). Toxicology tests on various objects demonstrated that the EBWNS has low toxicity for seeds, HaCaT cells, zebrafish, earthworm, and E. coli. This study provides a distinctive perspective for developing environmentally friendly nanopesticide formulations, which clarified a water-based treatment method for specific lipid-soluble pesticides. The water-based nanodelivery pesticide system has the potential to improve the efficacy and safety of pesticides in the process of field applications.

The nematicide emamectin benzoate increases ROS accumulation in Pinus massoniana and poison Monochamus alternatus.

Pine wilt disease (PWD) is caused by the pine wood nematode (PWN, Bursaphelenchus xylophilus) and transmitted by a vector insect, the Monochamus alternatus. The PWN has caused much extensive damage to pine-dominated forest ecosystems. Trunk injection of emamectin benzoate (EB) has been found to be the most useful protective measure against the PWN, due to its low effective dose and long residence time in the field. However, the interactions between EB and the host or the environment remain largely unknown, which limits the efficacy and stability of EB in practical field settings. In this study, we investigated the impact on PWN from EB injection for both adult and young host plants (Pinus massoniana) by taking a multi-omics (phenomics, transcriptomics, microbiome, and metabolomics) approach. We found that EB injection can significantly reduce the amount of PWN in both living adult and young pine trees. Additionally, EB was able to activate the genetic response of P. massoniana against PWN, promotes P. massoniana growth and development and resistance to Pine wilt disease, which requires the presence of PWN. Further, the presence of EB greatly increased the accumulation of reactive oxygen species (ROS) in the host plant in a PWN-dependent manner, possibly by affecting ROS-related microbes and metabolites. Moreover, we uncovered the function of EB limiting the consumption of P. massoniana by the JPS. Based on biochemical and gut microbial data, we found that EB can significantly reduces cellulase activity in JPS, whose transcription factors, sugar metabolism, and the phosphotransferase system are also affected. These results document the impact of EB on the entire PWD transmission chain through multi-omics regarding the dominant pine (P. massoniana) in China and provide a novel perspective for controlling PWD outbreaks in the field.

Efficacy of Certain Insecticides and Neem Products against Shoot and Fruit Borer [Earias vittella (Fabricius)] of okra [Abelmoschus esculentus (L.) Moench

A field trial was conducted at the research plot at Central Research Farm (CRF), Sam Higginbottom University of Agriculture, Technology and Sciences, Prayagraj, Uttar Pradesh, during the Rabi Season of 2022-2023 where eight treatments were replicated thrice in Randomized Block Design (RBD) Eight treatments i.e., Lambda cyhalothrin 2.5% EC @ 0.3ml/lit, Emamectin benzoate 5% SG @0.5ml/lit ,Spinosad 45%SC@1.3 ml/lit, Chlorantraniliprole 18.5%SC @0.5 ml/lit, Imidacloprid 17.80%SL @0.5ml/lit, Azadirachtin 1% EC @ 10ml/lit, NSKE 5% @ 50 ml/lit and untreated Control. The data on the percent infestation of the shoot and fruit borer on okra third, seven and fourth day after spray reveal that all the insecticides and neem products were significantly superior over control. Among all the different treatments lowest shoot and fruit infestation of okra was recorded in Chlorantraniliprole (10.21% ,9.98%) followed by Emamectin benzoate 5%SG (11.45%, 12.29%), Spinosad 45%SC (13.86%, 14.11%), Imidacloprid 17.80% SL (16.94,15.87%), Lambda cyhalothrin 2.5%EC (17.83, 16.03%), Azadirachtin 1% EC (19.25%, 17.04%) and NSKE 5% (20.35%, 18.75%), control (24.84%, 25.98%). The yields among the treatment were significant. The yield and benefit cost ratio was recorded in Chlorantraniliprole 18.5SC (195.5 q/ha) (1:9.3) followed by Emamectin benzoate 5% SG (149.2q/ha), (1:8.2), Spinosad 45 % SC (140.2q/ha), (1:8.11), Imidacloprid 17.80SL (136.3q/ha), (1:7.9), Lambda cychalothrin 2.5 EC (133.2q/ha), (1:7.6), Azadirachtin 1% (96.3q/ha) (1:5.5) and NSKE 5% (92.4q/ha) (1:5.2) as compared to, control (72.2q/ha), (1:4.2).

Field Efficacy of Insecticides and Botanicals for Management of Spotted Stem Borer (Chilo partellus) on Maize (Zea mays L.)

The field investigation was conducted during the Kharif 2021 and 2022 at the Central Research Farm (CRF) of Naini Agriculture Institute, Sam Higginbottom University of Agriculture Technology and Sciences, Prayagraj, Uttar Pradesh, India. The experiment was organized in a Randomized Block Design, comprising twelve treatments, each replicated thrice. The treatments included Chlorantraniliprole 18.5 SC (0.5 ml/l), Lambda cyhalothrin 2.5% EC (10 ml/l), Thiamethoxam 25 WG (10 gm/kg), Profenophos 50 EC (3ml/l), Cypermethrin 10 EC (4 ml/l), Neem oil 3% (30 ml/l), Verticillium lecani 1.15 WP (15 ml/l), Spinosad 45 SC (0.3 ml/l), Emamectin benzoate 5 SG (0.40 gm/kg), Indoxacarb 15.8 EC (1.5 ml/l), NSKE 5% (50 ml/l), and control plot. The results showed that the lowest population of stem borer was identified with Emamectin benzoate 5 SG (2.24), (0.82) and (3.61), (2.33) followed by Chlorantraniliprole 18.5 SC (2.41), (1.01) and (3.82), (2.46) during the Kharif seasons of both 2021 and 2022. Neem oil 3%, NSKE 5% were found to be least effective over the other treatments and is significantly superior over the control.

Evaluation of the effectiveness of spraying operations carried out by a drone/unmanned aerial vehicle (UAV) in comparison to the conventional approach forthe management of safflower aphids (Uroleucon compositae Theob) and safflowercapsule borer (Helicoverpa armigera Hubner)

The safflower variety ISF-764 was sown in the second fortnight of November, 2020. The Experiment comprised of three treatments Viz., T1: Spraying of Emamectin Benzoate 5% SG (200g /ha), Imidacloprid 17.8 SL (200ml /ha) with UAV; T2: Spraying of Emamectin Benzoate 5% SG (200g /ha) and Imidacloprid 17.8 SL (200ml/ha) with a power sprayer and T3: Untreated control. Both sprayers performed well in the management of Helicoverpa and Aphids. No Helicoverpa larval and Aphids populations were registered in T1: Spraying ofEmamectin Benzoate 5% SG (200g /ha), Imidacloprid 17.8 SL (200ml /ha) with UAVs at 3DAS, 10 DAS, respectively. The highest seed yield benefit cost ratio were ecorded in the plot sprayed with UAVs (1691 kg /ha& 4.36).

Effects of the sea lice chemotherapeutant, emamectin benzoate, on metabolism and behaviour of the sea-pen Pennatula phosphorea

Chemotherapeutants used to control infestations by sea lice can be released into the marine environment surrounding aquaculture farms. Among these therapeutic agents, emamectin benzoate is extensively utilized even though its impact on non-target taxa has not been thoroughly examined. In this context, we explored the effects of emamectin benzoate on a common Norwegian habitat-forming species: the phosphorescent sea-pen Pennatula phosphorea. Specifically, we examined P. phosphorea metabolic and responses before, during and after exposure to emamectin benzoate. Results indicate that an 8-day emamectin benzoate exposure (0.8 mg/L) did not induce P. phosphorea mortality or significant behavioural or metabolic modifications. However, we highlighted the presence and persistence of emamectin benzoate in exposed P. phosphorea tissue. These results indicate that emamectin benzoate is unlikely to adversely impact P. phosphorea populations in the environment. However, persistence of emamectin benzoate in tissue constitutes a potential for bioaccumulation with repeated treatments and should be examined in further studies.

COMPARATIVE EFFECT OF SOME BIO-PESTICIDES ON THE MANAGEMENT OF AFRICAN PINK STEM BORER, Sesamia calamistis (Hampson) (Lepidoptera: Noctuidae) ON SWEET CORN (Zea mays var. saccharata L.)

The study was conducted at Institute for Agricultural Research (IAR) horticultural garden Ahmadu Bello University, Zaria under irrigation in two dry seasons (2019 and 2020). The region is located at Latitude11º11'1N and Longitude7º38'E. The research was conducted to evaluate the effectiveness of two microbial pesticides: Emamectin benzoate and Beauveria bassiana, two botanical extracts: Karanjin from Pongamia glabra and Azadirachtin (Azadirachta indica), one synthetic insecticide: Lion Guard EC (with Cypermethrin 3% and dimethoate 25%) which served as Standard check. S. calamistis larvae were mass produced in the Insect Rearing Laboratory of the Department of Crop Protection using artificial diet to carry out field infestation. On the field, the treatments involved three maize varieties; Sweet Corn Yellow, Sugar King F2 and SAMMAZ 52 and also the five (5) pesticides with untreated control laid out in a Randomized Complete Block Design (RCBD) in split plot with three replications on a plots size of 9m2 (3 m x 3 m). Leaf damage, dead hearts, cob damage, exit holes, lodging, stem tunneling and yield ha-1 were measured. The data was subjected to ANOVA using SAS 9.0 and the means were separated using Student Newman Keul’s (SNK). Azadirachtin with 1.53, Karanjin with 2.22, Emamectin 1.48 and B. bassiana 1.42 larval mortality on the field after treatment application. Azadirachtin, Karanjin, Emamectin and B. bassiana reduced dead heart incidence by 46%, 20%, 51% and 52% respectively when compared with control in which 60% dead hearts incidence was recorded. Azadirachtin, Emamectin and B. bassiana were very effective in suppressing S. calamistis population, mitigated its ability to cause serious damage to the leaves, hearts, stem and cob of the maize and produced higher when compared with control. Even though Karanjin was less effective than the other three, it was better than control treatment. Azadirachtin can be applied at the rate of 0.44 Lha-1 and Karanjin at the rate of 0.5 Lha-1 to control of S. calamistis on sweet corn. B. bassiana and Emamectin benzoate can be applied at the rate of 0.25 Kgha-1 and 3 Kgha-1 to manage of S. calamistis.

Bio-Efficacy of Novel Insecticides and Biopesticides against Diamondback Moth, Plutella xylostella (Linn.)

The present investigation entitled ‘bio-efficacy of Novel insecticides and bio-pesticides against Diamondback moth, Plutella xylostella (Linn.) was carried out on the cabbage, variety ‘Golden Acre’ during Rabi, 2021-22 and 2022-23. At Crop Research Centre, Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut (UP). The data were recorded on five randomly selected plants once in a standard week. Pooled data of both the year (2021 and 2022), After treatments, spinosad 2.50% SC at 600 ml ha-1 consistently showed the lowest larval count on days 3, 7, and 14, with 3.33, 2.17, 2.25 larvae per five plants followed by emamectin benzoate 5% SG at 200 g ha-1, diafenthiuron 50% WP at 600g ha-1, Bacillus thuringiensis var. kurstaki at 1000 g ha-1, Beauveria bassiana at 1500 ml ha-1 and Metarhizium anisopiliae at 2000 g ha-1, and nimbecidine 0.03% at 2500 ml-ha, respectively. The nimbecidine 0.03% at 2500 ml ha-1 recorded the lowest efficacy. Chemical and biological treatments varied significantly, while chemicals had similar efficacy, and biologicals were equally effective. Control plots had the highest larvae count.

Study on Dissipation Law of Pesticides in Cauliflower Based on Hyperspectral Image Technique

In order to rapidly and non-destructively detect the residual rate of emamectin benzoate+indoxacarb pesticides on cauliflower, a study was conducted using hyperspectral technology to investigate the dissipation law of this pesticide over time. Hyperspectral imaging was employed to capture spectral data from cauliflower samples with and without the pesticide, focusing on the region of interest. The spectral data, consisting of 216 bands (ranging from 950 nm to 1666 nm), were preprocessed using techniques such as Savitzky–Golay convolution smoothing (S-G), multivariate scattering correction (MSC), and standard normal variate (SNV). Next, characteristic spectra for each pesticide were extracted using the competitive adaptive reweighted sampling algorithm (CARS). This study utilized the partial least squares (PLS) algorithm to construct a discriminative model aimed at identifying pesticide residues on cauliflower. The accuracy of the hyperspectral imaging technique was validated by comparing the results with those obtained through chromatography. The PLS model, optimized using the SNV method, exhibited the highest discriminant accuracy, achieving a recognition rate of 100%. The residual rate of indoxacarb detected through hyperspectral technology closely corresponded to the results obtained through chromatography. It was found that the discrepancy in the half-life of pesticides as detected by hyperspectral and chromatographic methods is a mere 0.14 days. These findings highlight the potential of hyperspectral imaging technology for studying pesticide dissipation on cauliflower and detecting pesticide residues.

Transgenerational hormesis and sublethal effects of five key insecticides for controlling Spodoptera frugiperda on its endoparasitoid Cotesia marginiventris.

The endoparasitoid Cotesia marginiventris (Cresson) is a promising biological control agent of the fall armyworm (FAW) Spodoptera frugiperda (Smith). Because the application of insecticides is one of the prime choices in pest management, we evaluated the sublethal and transgenerational effects of the five key insecticides-chlorantraniliprole, emamectin benzoate, spinetoram, Bacillus thuringiensis (Bt), and Mamestra brassicae nucleopolyhedrovirus (MbNPV)-on the parasitoid. Exposure to five insecticides at a concentration causing 10% mortality (LC10 ) caused hormetic effects in the parent generation (F0 ) by increasing the parasitism and reducing the immature duration. Interestingly, the hormetic response was also observed in the offspring generation indirectly exposed to the insecticides. Furthermore, insecticides increased the parasitism rate by 6.32-14.73% in the F1 generation, which was similar to that of the F0 generation (3.96-11.81%) compared with the control. No significant adverse effect was observed on the number of emerged parasitoids of the F1 and F2 generations. However, insecticides had a detrimental impact on body size and fecundity in the F1 and F2 generations, which showed a small body size with shorter hind tibiae and a significant reduction in the female ratio compared with the control; the exception was that chlorantraniliprole significantly improved the female ratio in the F2 generation. Five insecticides at LC10 induced transgenerational hormetic and sublethal effects on C. marginiventris. Our results provide a scientific basis for a better understanding of the long-term impacts of insecticides at sublethal doses on parasitoids, facilitating the development of improved integrated pest management programs for FAW control. © 2023 Society of Chemical Industry.

Biochemical and molecular characterization of chlorantraniliprole resistance in Spodoptera littoralis (Lepidoptera: Noctuidae)

Resistance is one major problem that reduces the efficacy of insecticides against insect pests. Understanding the biochemical and molecular foundations of insect resistance to insecticides can help achieve the objectives of insect control and resistance management. In this study, resistance to chlorantraniliprole was developed in a field strain of Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) over fifteen generations using the selection pressure. In addition, the biochemical basis of resistance and cross-resistance to other insecticides were investigated. Moreover, the expression of esterase and Cytochrome P450 (CYP450) genes was quantitatively estimated in S. littoralis on exposure to chlorantraniliprole by using real-time PCR.The LC50 values of chlorantraniliprole to the developed resistant strain (CHL-R) and the susceptible strain (Sus) were 2.256 and 0.0056mg/L (ppm), respectively, representing a resistance ratio (RR) of 402.85. The CHL-R strain showed no cross-resistance to chlorpyrifos, methomyl, lambada-cyhalothrin, emamectin benzoate, and spinetoram (RR ranged from 0.97 to 1.89). However, a low cross-resistance level was developed to methoxyfenozide (RR = 4.04) and a moderate level was developed to indoxacarb (RR = 30.83). Synergism assays suggested that CYP450 may be involved in resistance development in the CHL-R strain. Nevertheless, a significant decrease in Carboxylesterases (CarE) and Glutathione S-transferase (GST) activities was observed. Consistently, over-expression of the CYP450 gene was recorded in the CHL-R strain, which provides a foundation for understanding the mechanism of S. littoralis resistance to chlorantraniliprole in Egypt. Generally, our results provide valuable information for monitoring and managing S. littoralis resistance in Egypt.

The Comparison of Tolerance Capability of Nitrogen-Fixing Bacteria to Chemical and Biological Pesticides

Due to concerns about the adverse effects of synthetic pesticides on the environment and human health, there is a growing preference for environmentally friendly and safe pesticides. However, hard evidence to verify their low-risk characteristics is scarce. This work attempted to compare the effects of a chemical pesticide (alpha-cypermethrin) and a biopesticide (emamectin benzoate) on the growth of indigenous nitrogen-fixing bacteria. These bacterial strains were isolated from the rhizosphere of bean plant samples obtained from farmers? fields where these two pesticides were sprayed on bean crops. The results revealed that at the field-recommended concentration of both pesticides, the growth of the isolates in both nutrient-rich and nitrogen-free media remained largely unaffected. However, the bacteria?s absolute growth inhibition was recorded as the pesticide concentration increased. When the Tryptic Soy Broth medium was supplemented with a pesticide concentration 10 times higher than the recommended dose, up to 85.7% of the isolated strains were completely inhibited in growth when exposed to alpha-cypermethrin. In contrast, only 17.9% of bacterial strains were completely inhibited when exposed to emamectin benzoate. In a nitrogen-free medium, the proportion of inhibited bacteria was absolute when the medium was supplemented with alpha-cypermethrin and emamectin benzoate at a dosage 10 times higher than the recommended concentration, which reached 92.9% and 28.6%, respectively. The strains that exhibited higher tolerance to both pesticides were identified as Niallia nealsonii ND15 and Rhizobium subbaraonis ND27. Our findings emphasize the importance of minimizing pesticide accumulation in the soil to protect the viability of soil-beneficial bacteria and ensure soil quality for safe and sustainable crop production.. KEYWORDS :Alpha-cypermethrin, Emamectin benzoate, N-fixing bacteria, Pesticides tolerance, Toxicity assessment

NSECTICIDAL AACTIVITIES OF THE AQUEOUS EXTRACTS OF CHROMOLAENA ODORATA LEAVES AND ANACARDIUM OCCIDENTALE NUTSHELL LIQUID AGAINST INSECT PESTS OF CABBAGE AND ITS EFFECT ON YIELD

The current study investigated the insecticidal potential of Anacardium occidentale and Chromolaena odorata in managing the main insect pests of cabbage in field settings. The 2018 and 2019 major and minor rainy seasons were when the study was carried out. Four treatments were used: a normal insecticide (Emamectin benzoate, 3 mL/L), a water extract of C. odorata leaves, a water extract of A. occidentale nutshell liquid (50 g/L), and soapy water as a control. Four replicates were used in a Randomized Complete Block Design (RCBD) arrangement for these. The quantity and presence of insects, an evaluation of leaf damage, and an estimation of harvest yield were the data collected. Thirteen different species of insects were recorded, and classified as major, minor, and beneficial pests. Plutella xylostella and Hellula undalis infestations in the control group were generally much greater than those in the other treatments. The botanicals were more successful than the control at reducing the aphid population. In general, the botanicals outperformed the control in terms of Phyllotreta sp. and ant population; however, there was no discernible difference in the response for Zonoceros variagatus and cabbage white flies. The mean weights, head diameters, and mean head heights for each treatment showed a significant difference (p < 0.05). For both seasons, more than 60% of the leaves had damage ranging from 0% to 20% (Damage 1). The results of this study demonstrate the two botanicals insecticidal properties against the most common insect pests of cabbage, allowing them to be included in an integrated pest management (IPM) package.

The Lethal and Sublethal Effects of Lambda-Cyhalothrin and Emamectin Benzoate on the Soybean Pest Riptortus pedestris (Fabricius).

Riptortus pedestris (Fabricius, 1775) (Hemiptera: Alydidae) is a major soybean pest in East Asia that can cause soybean staygreen syndrome. To date, no insecticides have been registered for the control of R. pedestris in China, and these insects are primarily controlled in the field through the application of broad-spectrum insecticides including lambda-cyhalothrin (LCT) and emamectin benzoate (EMB). Here, the lethal and sublethal effects of LCT and EMB on R. pedestris were comprehensively evaluated. LCT and EMB were both found to exhibit high levels of toxicity and concentration-dependent repellent effects for R. pedestris. The exposure of third instar nymphs from the F0 generation to LC30 concentrations of LCT and EMB resulted in a significant increase in the duration of nymph development and adult pre-oviposition period (APOP), together with reductions in fifth instar nymph and adult body weight, longevity, oviposition days, fecundity, vitellarium length, lateral oviduct diameter, and vitellogenin (Vg) gene expression as compared to control treatment. Strikingly, these suppressive effects were transmitted to the F1 generation, which similarly experienced the prolongation of preadult development and the preoviposition period (TPOP). Relative to control-treated populations, the F1 generation for these insecticide-treated groups also exhibited significant decreases in population parameter values. Overall, these data offer new insight into the impact that LCT and EMB treatment can have on R. pedestris, providing a valuable foundation for the application of these pesticides in the context of integrated pest management strategies aimed at soybean crop preservation.

Botanical biopesticides have an influence on tomato quality through pest control and are cost-effective for farmers in developing countries.

Synthetic insecticides heavily applied to manage agricultural pests are highly hazardous to the environment and non-target organisms. Their overuse through repeated treatments in smallholder farming communities is frequent. Botanical biopesticides are ideal for sustainable pest management in agricultural environments by keeping synthetic insecticide use at a minimum. Here we evaluated a locally prepared neem seed extract (NSE) alongside emamectin benzoate against both lepidopteran pests Helicoverpa armigera (Hübner) and Spodoptera exigua (Hübner) on tomato Lycopersicon esculentum Mill under natural field conditions in Pakistan. We compared pest severity, fruit injury, quality, marketability, and cost:benefit ratio (CBR) between treatments. The concentration of azadirachtin A in the NSE was 26.5 ppm. NSE at 2% (20 mL/L) and the emamectin benzoate at the recommended field rate in Pakistan were sprayed weekly throughout the fruiting stage. The pest larvae were significantly more abundant on fruits than on flowers and leaves. Fruit injury and losses were significantly more important in untreated control compared to NSE and emamectin benzoate treatments. NSE efficacy varied with respect to the cultivars used and the seasons. Cultivar Eden harboured more pests than Adventa, and emamectin benzoate suppressed more pest individuals than NSE. Both the insecticidal treatments were comparable in terms of marketable yield productions as well as unmarketable, uninjured, and recovered fruit yields. NSE generated a higher CBR (1: 9.26) than emamectin benzoate (1: 3.23). NSE suppressed pests by acting as an antifeedant, similar to its synthetic counterpart. Smallholder growers can thus use NSE as a cost-effective solution in tomato pest management in Pakistan.

Trunk injection to control Xylosandrus germanus (Coleoptera: Curculionidae) in topworked apple trees.

Xylosandrus germanus (Blandford) is an invasive species of ambrosia beetle known to attack apple trees in North America. Xylosandrus germanus are attracted to ethanol produced by stressed and injured trees and can be a serious problem when grafting a new cultivar onto established fruit trees (topworking). The objective of this study was to evaluate the efficacy of 2 insecticides (emamectin benzoate and azadirachtin) and injection timing (fall and spring) on their ability to control X. germanus colonization in apple trees with simulated topworking. Our study shows evidence that both emamectin benzoate and azadirachtin injections can reduce X. germanus infestations; however, our results were inconsistent. The timing of injections influenced X. germanus, with spring injected azadirachtin being more effective than fall injections. Residue analyses of emamectin benzoate and azadirachtin showed the presence of residues in woody tissue comparable to those found in leaves.

Overexpression of the F116V allele of CYP9A186 in transgenic Helicoverpa armigera confers high-level resistance to emamectin benzoate

Insect cytochrome P450s play important roles in the detoxification of xenobiotics and the metabolic resistance to insecticides. However, the approach for in vivo validation of the contribution of specific candidate P450s to resistance is still limited in most non-model insect species. Previous studies with heterologous expression and in vitro functional assays have confirmed that a natural substitution (F116V) in the substrate recognition site 1 (SRS1) of the CYP9A186 of Spodoptera exigua is a gain-of-function mutation, which results in detoxification capability of and thus high-level resistance to both emamectin benzoate (EB) and abamectin. In this study, we established an effective piggyBac-based transformation system in the serious agricultural pest Helicoverpa armigera and overexpressed in vivo a resistance P450 allele, CYP9A186-F116V, from another lepidopteran pest Spodoptera exigua. Bioassays showed that transgenic H. armigera larvae expressing CYP9A186-F116V obtained 358-fold and 38.6-fold resistance to EB and abamectin, respectively. In contrast, a transgenic line of Drosophila melanogaster overexpressing this P450 variant only confers ∼20-fold resistance to the two insecticides. This bias towards the resistance level revealed that closely related species might provide a more appropriate cellular environment for gene expression and subsequent toxicokinetics of insecticides. These results not only present an alternative method for in vivo functional characterization of P450s in H. armigera and other phylogenetically close species but also provide a valuable genetic engineering toolkit for the genetic manipulation of H. armigera.

Effect of Botanicals on Fall Armyworm and Predators in Sorghum Ecosystem

The present field experiment was conducted at Agricultural College Farm, Bapatla during kharif (June-November), 2019 to know the impact of botanicals against fall armyworm, S. frugiperda and their natural enemies (coccinellids, spiders and predatory bugs) in the sorghum ecosystem. Among the botanicals, the highest population reduction of FAW egg masses and larval population was recorded in NSKE @ 5% (71.43 and 60.87%, respectively), green chilli pod extract @ 5% (61.90 and 54.35%, respectively), neem leaf extract @ 5% (69.05 and 45.65%, respectively) and garlic bulb extract @ 5% (52.38 and 54.35%, respectively) treated plots. The botanicals that are used in the experiment were found safe from natural enemies. The maximum population of natural enemies i.e., coccinellids, spiders and predatory bugs was recorded in pongamia leaf extract @ 5% (0.16, 0.22 and 0.10 plant-1, respectively) whereas, the least was observed in emamectin benzoate 5 SG @ 11 g a.i. ha-1 (0.02, 0.02 and 0.01 plant-1 respectively) treated plots. The emamectin benzoate 5 SG @ 11 g a.i. ha-1 presented an adverse effect on natural enemies whereas no or few natural enemies were observed compared to botanical extracts. Therefore, it is recommended that spraying of botanicals has to be done four times at weekly intervals to keep FAW populations below economic injury level until crop maturity and these treatments were also found safe to natural enemies of FAW.

Mulch from lignocellulose as agricultural plastic alternative for sustained-release of photosensitive pesticide

Extensively used agricultural mulch fabricated from nonbiodegradable polyolefin plastic causes tremendous environmental pollution. In this work, a paper-based mulch, composed of the cellulose fiber networks incorporated with Emamectin benzoate (EB)@sodium lignosulfonate (SL), has been developed with facile papermaking/coating methods. The spherical microcapsule loaded with pesticide EB has a desirable core-shell structure for better protection and sustained release of photosensitive EB. The loading rate and encapsulation efficiency reached 78.5 % and 52.3 %, respectively. Furthermore, microcapsules exhibited excellent slow-release behavior and resistance to photolysis. Natural carnauba wax was coated on the surface of the paper-based mulch to form a hydrophobic layer and increase the physical intertwinement of fibers in the mulch, thereby exhibiting superior performance, such as enhanced tensile strength, excellent hydrophobicity, high air permeability, and high light transmittance at reasonable level. Moreover, unlike conventional polyethylene mulch film, the functionalized paper-based mulch almost completely biodegraded after 75 days in the soil. Thus, multifunctional, eco-friendly mulch from lignocellulose is an innovative approach to obtaining the sustained release of agrochemicals, and it provides an excellent alternative to conventional agricultural plastic mulch.

Thermo-responsive liposome nano-vesicles for co-delivery of emamectin benzoate and nitenpyram with synergistic pest control

The conventional pesticide formulations often suffer from low utilization rates and trigger the development of resistance, leading to significant resource waste and ecological damage. A promising solution to these issues lies in the design of intelligent, nanotechnology-based systems for controlled-release and co-delivery of pesticides. A multi-compartment liposome nano-vesicle (Co-EM-Lip) that simultaneously carries emamectin benzoate (EB) and nitenpyram (Nit) has been developed, using a eutectic mixture (EM) of fatty acids as a temperature-sensitive “switch”. This Co-EM-Lip system successfully enabled the co-delivery of two pesticides with differing water solubility and insecticidal pathways, along with a thermo-responsive controlled release. The effectiveness of Co-EM-Lip against Plutella xylostella was approximately 4.4 times higher at 35 °C than at 15 °C, which is attributable to high temperature-triggered rapid release properties. Importantly, EB and Nit within Co-EM-Lip demonstrated synergistic biological effects against various pests. Additionally, Co-EM-Lip showed less toxicity to zebrafish. This research thus introduces a novel strategy to devise smart, controlled-release and co-delivery pesticide systems aimed at enhancing pesticide efficiency, delaying pest resistance, and minimizing environmental harm and impact on non-target organisms.