Emamectin Research Articles

Insecticidal Efficiency of Some Pesticides Against Spodoptera Frugiperda (J.E. Smith) (Noctuidae: Lepidoptera) Under Laboratory Conditions

The "fall armyworm," also known as Spodoptera frugiperda, is a maize pest that is native to North America. It invaded Africa in 2019 and caused serious economic damage, forcing the continent's nations to take swift action to protect off this new invading pest. In Egypt, a variety of chemical insecticides were promoted, but farmers quickly and repeatedly reported control failures. Fall armyworm samples were collected from five different maize-growing regions. Five widely available pesticide formulations: emamectin benzoate, chlorantraniliprole, indoxacarb, methomyl, and chlorpyriphos were tested under laboratory conditions against the 2nd and 4th instar larvae. The results demonstrated that S. frugiperda second-instar larvae were more vulnerable to all tested pesticides than fourth-instar larvae. Under laboratory circumstances, the LC50 values for the various substances were 0.090, 0.165, 0.243, 0.908, and 2.55 ppm, respectively. Furthermore, the insecticide emamectin benzoate was more effective than other pesticides. However, chlorpyriphos pesticide was the least harmful insecticide for controlling this bug. To determine how well these treatments perform against this pest, further trials are required.

Insecticidal Efficiency of Some Pesticides Against Spodoptera Frugiperda (J.E. Smith) (Noctuidae: Lepidoptera) Under Laboratory Conditions

The "fall armyworm," also known as Spodoptera frugiperda, is a maize pest that is native to North America. It invaded Africa in 2019 and caused serious economic damage, forcing the continent's nations to take swift action to protect off this new invading pest. In Egypt, a variety of chemical insecticides were promoted, but farmers quickly and repeatedly reported control failures. Fall armyworm samples were collected from five different maize-growing regions. Five widely available pesticide formulations: emamectin benzoate, chlorantraniliprole, indoxacarb, methomyl, and chlorpyriphos were tested under laboratory conditions against the 2nd and 4th instar larvae. The results demonstrated that S. frugiperda second-instar larvae were more vulnerable to all tested pesticides than fourth-instar larvae. Under laboratory circumstances, the LC50 values for the various substances were 0.090, 0.165, 0.243, 0.908, and 2.55 ppm, respectively. Furthermore, the insecticide emamectin benzoate was more effective than other pesticides. However, chlorpyriphos pesticide was the least harmful insecticide for controlling this bug. To determine how well these treatments perform against this pest, further trials are required.

Resveratrol improves emamectin benzoate-induced pyroptosis and inflammation of Ctenopharyngodon idellus hepatic cells by alleviating oxidative stress/endoplasmic reticulum stress

Emamectin benzoate (EMB) is the most widely used pesticide in the world and contributes to water pollution. Owing to the lack of a specific antidote, EMB has a severe negative impact on the health of aquatic organisms. Resveratrol (RES), a substance with antioxidant capacity, is secreted by the fruits of many plants. This study was to explore the protection of RES against EMB-induced pyroptosis and inflammatory response in grass carp (Ctenopharyngodon idellus) hepatic liver (L8824) cells by oxidative stress/endoplasmic reticulum (ER) stress. The results showed that compared to the CON group, EMB induced oxidative stress in L8824 cells with the increase of reactive oxygen species (ROS), methane dicarboxylic aldehyde (MDA), and hydrogen peroxide (H2O2) contents and the decrease of total superoxide dismutase (t-sod) and glutathione peroxidase (gsh-px) activities (P < 0.05). In addition, EMB triggered ERS, increasing the relative mRNA expression of protein kinase R-like endoplasmic reticulum kinase (perk), inositol requiring enzyme 1 alpha (ire1α), glucose-regulated protein 78 (grp78), activating transcription factor 4 (atf4), activating transcription factor 6 (atf6), and CCAAT-enhancer-binding protein homologous protein (chop) and the protein expression of eukaryotic initiation factor 2α (eif2α), chop, atf6, and atf4. Meanwhile, EMB further induced pyroptosis by upregulating the mRNA and protein expression of nlrp3, aptamer protein (asc), caspase-1, gsdmd, interleukin-1β (il-1β), and interleukin-18 (il-18). EMB also induced inflammation in L8824 cells by increasing the mRNA expression of interleukin-2 (il-2), interleukin-6 (il-6), tumor necrosis factor-α (tnf-α), and ifn-γ and decreasing the content of interleukin-10 (il-10). However, compared to the EMB group, the oxidant indices and expression of genes related to ER stress, pyroptosis, and pro-inflammatory factors were significantly down-regulated (P < 0.05), whereas the antioxidant indicators and anti-inflammatory factor were significantly up-regulated in the EMB + RES group (P < 0.05). In conclusion, EMB caused hepatocytes pyroptosis and inflammation in grass carp, and RES could alleviate EMB-induced pyroptosis and inflammation in L8824 cells by ameliorating oxidative stress/ER stress.

Seed Treatment with Insecticides- A Potential Option against Fall Army Worm &lt;i&gt;Spodoptera frugiperda&lt;/i&gt; in Maize

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

Evaluation of Different Insecticides against Spotted Pod Borer, M. vitrata Infesting Vegetable Cowpea

A field experiment was conducted at Anand Agricultural University, Anand during kharif 2021 to assess the bio-efficacy various insecticides against spotted pod borer, Maruca vitrata infesting vegetable cowpea of the nine evaluated insecticides chlorantraniliprole 18.5% SC, emamectin benzoate 5% SG were found the most effective in reducing the incidence of M. vitrata. However, spinetoram 11.7% SC and spinosad 45% SC were found mediocre in their effectiveness. Maximum (76.33 q/ha) green cowpea pod yield was recorded from the plot treated with chlorantraniliprole which was at par with emamectin benzoate (75.50 q/ha). The highest ICBR returns were obtained in the treatment of emamectin benzoate (1: 11.48) followed by chlorantraniliprole (1: 8.67), spinetoram (1: 5.20) and spinosad (1: 4.92).

Field Efficacy of Different Insecticides Against Fall Armyworm (Spodoptera frugiperda J.E. Smith) in Spring Maize (Zea mays L.)

An experiment was conducted from February to June 2022 to determine the effectiveness of different insecticides in controlling fall armyworm (Spodoptera frugiperda: FA) under field conditions. The experiment followed a randomized complete block design (RCBD) with 5 treatments and 4 replications. Insecticides were applied three times at 7-day intervals. The treatments included: T1 - untreated or control (water spray), T2 - Cypermethrin 5% + Chlorpyriphos 50% EC, T3 - Chlorantraniliprole 18.5% SC, T4 - Emamectin Benzoate 5% SG, and T5 - Spinetoram 11.7% SC. Data were collected for the number of live larvae, damage to the top four leaves and whorls, and yield attributes. The results showed that the lowest FA infestation was observed in the plots treated with Chlorantraniliprole 18.5% SC, while the highest infestation was observed in the control group. The highest yield (7.52 t/ha) was obtained from the Emamectin Benzoate treatment, while the lowest yield (5.74 t/ha) was recorded in the control group. Among the different control measures, spraying Chlorantraniliprole 18.5% SC at 7-day intervals was found to be the most effective method to control FA in spring maize variety TX-369, achieving 100% efficacy. These results provide valuable guidance to growers in selecting effective insecticides for FA control. This study addresses the challenge of FA management in maize crops while aligning with multiple Sustainable Development Goals (SDGs).

Comparative Efficacy of Certain IPM Strategies Against Tobacco Caterpillar and Head Borer in Sunflower

The Experiments was conducted at Regional Research and Technology Transfer Station, Ranital, Bhadrak, OUAT(Odisha University of Agriculture and Technology), Odisha, India during the summer seasons(Jan-may) of 2019–20 and 2020–21 to evaluate the comparative efficacy some IPM modules against the head borer and leaf eating caterpillar in sunflower. Five IPM modules(three chemo-intensive and two bio-intensive modules) were evaluated against the existing pesticides application-based farmers’ practice. The results revealed that the IPM module (M2) comprising of installation of pheromone traps for pest monitoring @ 5 ha-1, poison baits (10 kg rice bran+2 kg jaggery+100 g Thiodicarb 70WP) for attracting and killing of tobacco caterpillar larvae and alternate spray of neem oil formulations (1500 ppm) @ 1.5 l ha-1 and the novel insecticide mixed formulation (Novaluron 5.25%+Emamectin benzoate 0.9% SC) @ 825 ml ha-1 at 15 days interval had significantly suppressed tobacco caterpillar (5.46% leaf damage i.e.. 67.59% reduction over FP) and sunflower head (2.93% head damage i.e. 75.32% deduction over FP). The IPM module ( M3) comprising of pheromone trap installation @ 5 each ha-1,poison baits (10 kg rice bran+2 kg jaggery+200 ml deltamethrin 5EC) and alternate spray of neem oil formulations (1500 ppm) @ 1.5 l ha-1 and Flubendiamide 480 SC @ 150 ml ha-1) also had statistically similar efficacy against the target pests with 6.40% leaf damage (62.02% reduction over FP) and 3.54% head damage(70.17% reduction over FP). Though, the BIPM module had moderate efficacy against the insect-pests under study, retained maximum population of predatory fauna like predatory bug (Eocanthecona furcellata) and lady bird beetles in the sunflower ecosystem.

Enhancement of photocatalytic activity of Ba-doped CoO for degradation of Emamectin benzoate in aqueous solution.

The present study was focused on the preparation of cobalt oxide (CoO) and barium-doped cobalt oxide (Ba-doped CoO) by following the co-precipitation method for the degradation of Emamectin benzoate pesticide in the aqueous medium. The prepared catalysts were characterized using SEM, EDX, and XRD to confirm the formation of catalysts and to observe the variation in the composition of catalysts during the degradation study. It can be suggested from the results of SEM, EDX, XRD, and FTIR analyses that Ba atom has successfully incorporated in the crystalline structure of CoO. The degradation of Emamectin benzoate pesticide was studied under the influence of different factors like solution pH, the dose of catalyst, contact time, temperature, and initial concentration of pesticide. It was observed that solution pH affects the degradation of the pesticide, and maximum degradation (23% and 54%) was found at pH 5.0 and 6.0 using CoO and Ba-doped CoO, respectively. The degradation of pesticides was found to be increased continuously (27-35% in case of CoO while 47-58% in case Ba-doped CoO) with the time of contact. However, the degradation was found to be decreased (23-3% in case of CoO while 47-44% in case Ba-doped CoO) with an increase in temperature. Likewise, in the beginning, degradation was observed to be increased up to some extent with the dose of catalyst and initial concentration of pesticide but started to decrease with further augmentation in the dose of catalyst and initial concentration of pesticide. It may be concluded from this study that doping of Ba considerably enhanced the photocatalytic ability of CoO for Emamectin benzoate pesticide.

Susceptibility and diagnostic concentration for Bacillus thuringiensis toxins and newer chemical insecticides in Spodoptera frugiperda (Lepidoptera: Noctuidae) from China.

The fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), is a cosmopolitan pest that exploits more than 350 host plants, including economically important crops such as corn, cotton and rice. Control of S. frugiperda largely relies on transgenic crops producing insecticidal proteins from Bacillus thuringiensis (Bt) and spraying synthetic insecticides. Here, we established the susceptibility and diagnostic concentration for 2 Bt toxins and 5 newer insecticides in invasive populations of S. frugiperda from southeastern China. Concentrations causing 50% mortality (LC50) in ten field populations sampled in 2022 ranged from 2.13 to 19.29 and 22.43 to 71.12 ng/cm2 for Cry1Fa and Vip3Aa, and 0.83 to 5.30, 2.83 to 9.94, 0.04 to 0.23, 4.59 to 8.40, and 1.49 to 6.79 mg/liter for chlorantraniliprole, chlorfenapyr, emamectin benzoate, indoxacarb, and spinosad, respectively. Relative to the susceptible strain YJ-19, the largest resistance ratio in the field populations was 5.1, 1.6, 6.2, 3.9, 4.6, 2.2, and 3.6 for Cry1Fa, Vip3Aa, chlorantraniliprole, chlorfenapyr, emamectin benzoate, indoxacarb, and spinosad, respectively, indicating that the field populations were generally susceptible to these Bt toxins and insecticides. Based on the pooled response of the field populations, the diagnostic concentration for resistance monitoring, estimated as ca. twice the LC99, was 400 and 1,500 ng/cm2 for Cry1Fa and Vip3Aa, and 2, 40, 60, 60, and 100 mg/liter for emamectin benzoate, chlorantraniliprole, chlorfenapyr, spinosad, and indoxacarb, respectively. These results provide useful information for monitoring resistance to key Bt toxins and insecticides for the control of S. frugiperda in China.

Method validation and monitoring of emamectin benzoate in mature banana fruit with peel and pulp through Liquid chromatography-Mass spectrometry/ Mass spectrometry (LC-MS/MS)

Emamectin benzoate has been frequently used in the banana ecosystem to combat the damage of pseudostem weevil. Therefore, the present study was conducted to validate the method, to assess harvest time residues and monitor emamectin benzoate residues in mature banana peel and pulp samples through LC-MS/MS. The validated method was used to determine emamectin benzoate residue in market banana samples. The study used Waters Alliance LC and Acquity TQD with an electrospray ionization interface in the positive ion mode. An isocratic flow of 0.1% formic acid (HCOOH) in water and 0.1% HCOOH in acetonitrile (CH3CN) was utilised for separation. CH3CN was utilised to extract emamectin benzoate residue from the samples, and a dispersive solid-phase extraction technique was used for subsequent cleanup. Linearity tests were performed with standard solutions containing 0.01 to 0.1 g mL-1, with three replicates for each concentration. For mature banana peel &amp; pulp and mature banana pulp matrices, satisfactory recoveries of 79.85 to 95.09% and 89.20 to 100.94%, respectively and high precision relative standard deviations of 0.56 to 2.34% and 2.33 to 6.88%, respectively were obtained. For mature banana (peel and pulp, pulp alone) fruits, the lower detection and quantification limits were (0.003, 0.008), and (0.002, 0.007). The validated approach was utilised to analyse mature banana fruit samples obtained from emamectin benzoate treated fields and banana samples purchased from the local market. Results showed satisfactory validation of parameters like linearity, the limit of detection and quantification, and recovery for determining emamectin benzoate residues in banana fruit.

Management strategy for Spodoptera frugiperda (Lepidoptera:Noctuidae) in mountain maize planting areas in China

The fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), is a major maize pest worldwide and has caused huge economic loss. To explore the control tactics of S. frugiperda in mountain maize planting fields, studies were performed in China from 2020 to 2021 for screening the S. frugiperda-resistant maize variety, seed coating agents, chemical insecticides, and biological agents. The results showed that 75 g/hm2 Emamectin benzoate had better controlling efficacy (with a control efficacy of 91.05% at 1d) than other chemicals, so it was recommended in the high incidence period of pests. Compared with other seed coating treatments, 50% Lumingwei TM625FS (with a control efficacy of 76.19% at 10d) was the best seed coating against S. frugiperda. The biological control “Telenomus remus + Picromerus lewisi” and “T. remus + Eocanthecona furcellata” had good control efficacy on S. frugiperda with 76.01%, 64.10% at 20d, respectively. Additionally, there were lower numbers of S. frugiperda in maize variety GuiDan6, BaoYu9, and YanBaiYu8. In summary, this research recommended four effective pest management strategies (GuiDan6-resistant maize variety, 50% Lumingwei TM625FS-seed coating agents, 5% emamectin benzoate-chemical pesticide, and “T. remus + P. lewisi”-biological control) in mountain maize planting fields. The study provided effective control strategies for S. frugiperda.

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

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

The knockout of the nicotinic acetylcholine receptor subunit gene α1 (nAChR α1) through CRISPR/Cas9 technology exposes its involvement in the resistance of Spodoptera exigua to insecticides

Insect nicotinic acetylcholine receptors (nAChRs) are the directed targets of many insecticides. However, there have been no reports on the molecular characterization of the nAChR gene family or the causal association between nAChR α1 and resistance to insecticides in S. exigua, which is a significant agricultural pest. In this study, we identified a total of 9 candidate nAChR subunits in S. exigua, namely nAChR α1-α7 and nAChR β1-β2. For functional validation roles of Seα1 in insecticide resistance of S. exigua, we introduced a ∼ 1041-bp deletion of the Seα1 gene in a homozygous mutant strain (Seα1-KO) by CRISPR/Cas9 genome editing system, resulting in a premature truncation of the Seα1 protein and the subsequent loss of functional transmembrane (TM) 3 and TM4 elements. Compared with WH-S strain (wild-type strain), the Seα1-KO strain exhibited 2.62-folds resistant to trifluoropyrimidine, 8.3-folds resistant to dimehypo, and 5.28-folds resistant to dinotefuran, but no significant change in susceptibility to emamectin benzoate, spinetoram, lambda-cyhalothrin, permethrin and chlorpyrifos. Thus, this study has laid a solid foundation for investigating the role of nAChRs in S. exigua, and provides evidence for the crucial involvement of the α1 subunit in the mechanism of trifluoropyrimidine, dimehypo, and dinotefuran in S. exigua. Moreover, it provides a reference for the value of Seα1 subunit and its homologues in other species as insecticide targets.

Involvement of Glutamate Cysteine Ligase Genes in Tolerance to Emamectin Benzoate in Spodoptera frugiperda and Their Putative Regulatory Mechanisms.

As the rate-limiting enzyme in de novo Glutathione (GSH) biosynthesis, the mammalian glutamate cysteine ligase (Gcl) catalytic (Gclc) and modifier (Gclm) subunits are regulated at multiple levels, whereas the function and regulatory mechanism of insect Gcl remain to be explored. In this study, we identified and characterized SfGclc and SfGclm in Spodoptera frugiperda. SfGclc and SfGclm were highly expressed in the hindgut and relatively less expressed in other tissues. The exposure of the third instar larvae to LC30 of emamectin benzoate (EMB) significantly reduced the GSH content with a concomitant upregulation of SfGclc and SfGclm. Further in vivo pretreatment with L-BSO, the Gcl inhibitor, increased the susceptibility of S. frugiperda to EMB. Consistently, overexpression of SfGclc and SfGclm increased the Sf9 cell viability under EMB treatment. Finally, both RNAi and the dual-luciferase reporter assay in Sf9 cells revealed that SfGclc is regulated by transcription factor CncC. These data provide insights into the function and regulatory mechanism of insect Gcl, and they imply that disruption of the redox homeostasis might be a practical strategy to enhance the insecticidal activity of EMB and other insecticides.

Assessment of Integrated Pest Management Modules against Fall Army Worm and Its Economic Impact in Maize

Aim: The present study was undertaken to assess the IPM modules and their economic impact against Fall Armyworm in maize through on farm trail (OFT).&#x0D; Place and Duration of Study: The present study was carried out in the farmers’ fields of Bhadradri Kothagudem district of Telangana during Rabi 2019-20, 2020-21 and 2021-22.&#x0D; Methodology: The main objective of on farm trail is to test and evaluate the findings of the research stations at the farmer's field and to refine and modify the technologies, if required for better adoption by farmers. The KVK, Bhadradri Kothagudem conducted on farm trail for the management of fall armyworm in maize during Rabi 2019-20, 2020-21 and 2021-22, as part of technical programme of Krishi Vigyan Kendra, Bhadradri Kothagudem in KVK operational area of adopted villages.&#x0D; Results: In technology assessment plot (On farm trail) the treatments followed were avoiding staggered sowing of maize, installation of pheromone traps @ 8-10 per acre, clean cultivation, balanced application of fertilizers, erection of bird perches @10/acre, spraying of Azadiractin (1500ppm) to repel the egg laying and need based whorl application of Emamectin benzoate @ 0.5g/l and Metarrhizium anisopliae @ 5g/l of water, if more than8 adult moths were trapped in the pheromone trap for three consecutive days. It was compared with the farmers practice plots i.e application of Carbofuran 3G granules @ 3kg/acre and indiscriminate usage of fertilizers and insecticides. The experiment was conducted in five locations. The benefit cost ratio (BC Ratio) was higher in technology assessed plots with 2.78, 2.63 and 2.75 whereas BC ratio was comparatively lower in farmers practice plots with 2.43, 2:21 and 2.25 in corresponding Rabi 2019-20, 2020-21 and 2021-22 respectively. &#x0D; Conclusion: Technology assessed package proved its effectiveness among maize farmers with increased net returns, lower per cent of FAW incidence and high yield and BC ratio compared to the farmers practiceduring Rabi 2019-20, 2020-21 and 2021-22, respectively. Hence, this on farm trial proved to be feasible for demonstration in wide scale to farming community of Bhadradri Kothagudem district.

Preparation of Salicylic Acid-Functionalized Nanopesticides and Their Applications in Enhancing Salt Stress Resistance.

Soil salinization is one of the global ecological and environmental problems that are tremendously threatening to the sustainable development of agriculture and food supply. In this work, a facile strategy was proposed to enhance the salt stress resistance of plants by preparing salicylic acid (SA)-functionalized mesoporous silica nanocarriers loaded with emamectin benzoate (EB). The obtained nanopesticides demonstrated a particle size of less than 300 nm. As an endogenous plant hormone, the grafting of SA in this nanopesticide system improved the uptake and translocation of pesticides in cucumber plants by 145.06%, and the applications of such nanopesticides enhanced the salt stress resistance of plants. This phenomenon was accounted for by the SA-functionalized nanopesticides increasing the superoxide dismutase and peroxidase activities (640 and 175%, respectively) and reducing the malondialdehyde content (54.10%), correspondingly alleviating the accumulation of reactive oxygen species and cell damage in plants. The above results were also confirmed by Evans blue staining and NBT staining experiments on cucumber leaves. In addition, these nanopesticides exhibited high insecticidal toxicity, and they also demonstrated biosafety toward nontarget organisms due to their sustained release property. Therefore, this work developed a biosafe SA-functionalized nanopesticide system, and these newly developed nanopesticides have potential in the agricultural field for enhancing salt stress resistance of plants.

Synergistic and additive interactions of Shewanella sp., Pseudomonas sp. and Thauera sp. with chlorantraniliprole and emamectin benzoate for controlling Spodoptera litura (Fabricius)

The imprudent use of insecticides causes the development of resistance in insect pest populations, contamination of the environment, biological imbalance and human intoxication. The use of microbial pathogens combined with insecticides has been proposed as an alternative strategy for insect pest management. This IPM approach may offer effective ways to control pests, in addition to lowering the risk of chemical residues in the environment. Spodoptera litura (Fabricius) is a major pest of many crops like cotton, maize, tobacco, cauliflower, cabbage, and fodder crops globally. Here, we evaluated the combined effects of new chemistry insecticides (chlorantraniliprole and emamectin benzoate) and entomopathogenic bacterial strains, Shewanella sp. (SS4), Thauera sp. (M9) and Pseudomonas sp. (EN4) against S. litura larvae inducing additive and synergistic interactions under laboratory conditions. Both insecticides produced higher larval mortality when applied in combination with bacterial isolates having maximum mortality of 98 and 96% with LC50 of chlorantraniliprole and emamectin benzoate in combination with LC50 of Pseudomonas sp. (EN4) respectively. The lower concentration (LC20) of both insecticides also induced synergism when combined with the above bacterial isolates providing a valuable approach for the management of insect pests. The genotoxic effect of both the insecticides was also evaluated by conducting comet assays. The insecticide treatments induced significant DNA damage in larval hemocytes that further increased in combination treatments. Our results indicated that combined treatments could be a successful approach for managing S. litura while reducing the inappropriate overuse of insecticides.

Studies on immunotoxicity induced by emamectin benzoate in zebrafish embryos based on metabolomics.

Emamectin benzoate (EMB) is an insecticide for the control of agricultural lepidoptera pests, and also an anti-parasiticide for the control of exoparasites in aquaculture industry. Increased studies suggest that EMB could cause toxicity to non-targeted organisms, but its immunotoxicity to human remains unclear. In this study, zebrafish were used to investigate the immunotoxic effects induced by environmentally relevant doses of EMB. We observed that EMB exposure led to embryo mortality and delayed hatching, as well as increased malformations. Meanwhile, zebrafish exposed to EMB exhibited a significant decrease in the number of neutrophils and macrophages. In addition, untargeted metabolomics approach was developed to elucidate the mechanism of EMB-induced immunotoxicity. We found that a total of 10 shared biomarkers were identified in response to EMB exposure. Furthermore, pathway analysis identified glycerophospholipid metabolism was the most relevant pathway. Within this pathway, it was observed abnormal increases in glycerol 3-phosphate content, which could be attributed to the increased expression of GK5 and decreased expression of GPAT3. Our study provided novel and robust perspectives, which showed that EMB exposure to zebrafish embryos could cause metabolic disturbances that adversely affected development and immune system.

The effects of SLICE®- and ivermectin-contaminated sediment on avoidance behaviour and oxygen consumption in marine benthic invertebrates

Pest management strategies to reduce sea lice infestations in the salmon aquaculture industry include in-feed treatments with ivermectin (IVM) and SLICE® (active ingredient [AI] emamectin benzoate [EMB]), which can result in local contamination of the environment. These compounds partition to sediments, have moderate persistence, and may pose a risk to non-target benthic organisms. The sub-lethal effects of EMB, IVM and a combination of both (EMB/IVM) on the benthic amphipod Eohaustorius estuarius and polychaete Nereis virens at environmentally relevant sediment concentrations were examined in subchronic exposures (28-30-d). E. estuarius avoided sediment containing >50 μg/kg IVM alone and in combination with EMB. N. virens avoided sediment with >50 μg/kg IVM and >0.5 μg/kg EMB/IVM and exhibited impaired burrowing and locomotory behaviour with both treatments. Oxygen consumption was significantly decreased in E. estuarius (up to 50% compared to controls) and increased in N. virens (by ∼ 200%) when exposed to EMB, IVM and EMB/IVM at concentrations <5 μg/kg. IVM, SLICE® and combination exposures at environmentally relevant concentrations caused adverse effects in E. estuarius and N. virens which could significantly alter organism fitness near salmon aquaculture operations.

Toxicity of Selective Insecticides against &lt;i&gt;Trichogramma chilonis&lt;/i&gt;

Entomotoxic potential of selective insecticides against Trichogramma chilonis Ishii was performed at the Toxicology Laboratory of Entomological Research Institute, Ayub Agriculture Research Institute (AARI), Faisalabad. Six insecticides viz., spinetoram, lufenuron, chlorantraniliprole, indoxacarb, flubendiamide and emamectin benzoate were tested against Trichogramma chilonis. After 3 and 24 hours of exposure to immature and adult stages of T. chilonis the observations were made. Egg card and dipped surface residue bioassays were used, to determine the mortality rate of immature and mature life stages of T. chilonis, respectively. The treatments flubendiamide, chlorantraniliprole, indoxacarb, and lufenuron are found relatively safe, whereas spinetoram and emamectin benzoate showed a high level of toxicity. After four hours, chlorantraniliprole and lufenuron showed low toxicity, flubendiamide and indoxacarb demonstrated moderate toxicity, while spinetoram and emamectin benzoate demonstrated significant toxicity for adults.