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The present study aims to evaluate the different nanoparticles (Cu NPs, KI NPs, Ag NPs, Bd NPs, and Gv NPs) against 4th instar Spodoptera frugiperda larvae as well as the microbial toxicity, phytotoxicity, and soil pH. Nanoparticles were tested at three concentrations (1000, 10000, and 100000 ppm) using two methods (food dip and larvae dip) against S. frugiperda larvae. Results (from the larval dip method) showed that among the nanoparticles, the KI NPs caused 63%, 98%, and 98% mortality within 5 days in the treatment of 1000, 10000, and 100000 ppm, respectively. After 24 h post treatment, a 1000 ppm concentration showed 95%, 54%, and 94% germination rates in Metarhizium anisopliae, Beauveria bassiana, and Trichoderma harzianum, respectively. The phytotoxicity evaluation clearly showed that NPs did not affect the morphology of the corn plants after the treatment. The soil nutrient analysis results showed that no effect was observed in soil pH or soil nutrients compared to control treatments. The study clearly showed that nanoparticles are caused toxic effect against S. frugiperda larvae.

Soil deterioration is a major cause of poor agricultural productivity, necessitating sufficient nutrient inputs like fertilizers and amendments for sustainable use. As one such strategy, the current study evaluates the potential of Sargassum wightii, a brown seaweed extract, as an osmopriming agent to improve seed germination, early establishment, and competent seedling performances in acidic soil. The elemental makeup of seaweed extract (BS) showed that it included major plant macro (Potassium, Nitrogen and Phosphorous), as well as micronutrients (Magnesium and Iron) and trace elements (Zinc, Copper, and Molybdenum). While seed germination was impacted by H + ion toxicity, seeds primed with BS emerged earlier and showed a higher germination percentage (98.2%) and energy (92.4%). BS treatments enhanced seedling growth by 63% and had a positive effect on root growth (68.2%) as well as increases in root surface area (10%) and volume (67.01%). Stressed seedlings had 76.39% and 63.2% less carotenoid and chlorophyll, respectively. In seedlings treated with BS, an increase in protein and Total Soluble Sugars content of 14.56 and 7.19%, respectively, was seen. Fourier Transform-Infra Red analysis of postharvest soil indicated improved soil health with absorbance corresponding to enhanced soil water holding capacity and organic matter. Increased abscisic acid synthesis rate and associated antioxidant enzyme system (Malondialdehyde, Glutathione peroxidases and ascorbate peroxidase) activation, along with enhanced H + adenosine triphosphate-ase and glutathione activities, help ameliorate and deport H + ions from cells, scavenge Reactive Oxygen Species, thus protecting cells from injury. Seaweed extract successfully reduced H + -induced ion toxicities in rice by promoting their germination, physiological, metabolically, and growth parameters that could ultimately increase their productivity and yield in a sustainable and environmentally friendly manner., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Green pesticides, derived from natural sources, have gained wider attention as an alternative to synthetic pesticides for managing polyphagous pests, such as Spodoptera litura. In this study, the methanolic flower extract of Nyctanthes arbor-tristis (Mx-Na-t) was subjected to chemical screening, and 3-hydroxy-1,2-dimethyl-4(1H)-pyridone (3H-dp) and tyrosol (Ty-ol) were identified as the major derivatives. The toxic effects of Mx-Na-t (500 ppm) were highest in third-instar S. litura larvae (96.4%), while those of 3H-dp and Ty-ol (5 ppm) were highest in second-instar larvae (76.5% and 81.4%, respectively). The growth and development of S. litura larvae and pupae were significantly reduced by all three treatments. Fecundity rates were also reduced by all treatments [from 1020 eggs (control) to 540 eggs by Mx-Na-t treatment, 741 eggs by 3H-dp treatment, and 721 eggs by Ty-ol treatment]. The extract and its active constituents decreased adult emergence and slowed total larval development in a dose-dependent manner. A decrease was noted in the major gut enzymes of young S. litura larvae exposed to Mx-Na-t, 3H-dp, and Ty-ol. Moreover, midgut tissues of fourth-instar larvae were severely damaged by Mx-Na-t (250 ppm), 3H-dp (2.5 ppm), and Ty-ol (2.5 ppm); the treatments induced structural damage to the epithelial cells and gut lumen. The earthworm Eisenia fetida was used to assess nontarget toxicity. Compared with cypermethrin, the phytochemicals exhibited minimal effects on the earthworm's detoxifying enzymes superoxide dismutase and catalase after 14 days of treatment. Moreover, in silico predictions using BeeTox and ProTox-II indicated little or no toxicity of 3H-dp and Ty-ol toward honey bees and other nontarget species., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Globally, soil acidification is a serious environmental issue that reduces commercial agricultural production. Rice is subjected to nutritional stress due to acidic soil, which is a major impediment to rice production. Since acid soil threatens rice plants with soil compaction, nutrient loss, and plant stress-induced oxidative cell damage that results in affecting the photosynthetic system, restricting the availability of water, and reducing overall plant growth and productivity. Since contemporary soil acidification management strategies provide mediocre results, the use of Sargassum wightii seaweed-based biostimulants (BS) and soil amendments is sought as an environmentally friendly alternative strategy, and therefore its potential isevaluated in this study. BS was able to mediate soil quality by improving soil pH and structure along with facilitating nitrogen phytoavailability. BS also increased the activity of the antioxidant enzyme system, superoxide dismutase ((48%), peroxidase (76.6%), and ascorbate peroxidase (63.5%), aggregating the monaldehyde-mediating accumulation of osmoprotective proline in roots, that was evident from rapid initiation of root hair growth in treated seedlings. BS was also able to physiologically modulate photosynthetic activities and chlorophyll production (24.31%) in leaves, maintaining the efficiency of plant water use by regulating the stomatal conductance (0.91 mol/m/s) and the transpiration rate (13.2 mM/m/s). The BS compounds were also successful in facilitating nitrogen uptake resulting in improved plant growth (59%), tiller-panicle number, and yield (52.57%), demonstrating a resourceful nitrogen use efficiency (71.96%) previously affected by stress induced by acid soil. Therefore, the study affirms the competent potential of S. wightii-based soil amendment to be applied not only to improve soil quality, but also to increase plant production and yield., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships has no potential competing interests:Sengottayan, Senthil-Nathan reports financial support was provided by DST-FIST., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Although the ecotoxicity of carbon-based nanomaterials (CBNs) is known, the potential effect of carbon nanofibers (CNFs) on edaphic organisms has been insufficiently explored. Thus, we aimed at the ecotoxicity of CNFs (at 10 and 100 mg/kg) in Lumbricus terrestris earthworms naturally infected with Monocystis sp. After 28 days of exposure, treatments did not affect the survival rate. However, we observed a significant loss of body biomass, and Monocystis sp. infection in seminal vesicles was potentiated by exposure to CNFs. Earthworms exposed to CNFs showed a redox imbalance in the seminal vesicle, muscle, and intestine and an alteration in nitric oxide production in these organs. In muscles, we also noticed a significant reduction in AChE activity in earthworms exposed to CNFs. The histopathological analyses revealed the treatments' significant effect on the structures of the different evaluated tissues. Although we did not notice a concentration-response for several of the biomarkers, when taken together and after the application of Integrated Biomarker Response (IBR) and principal component analysis (PCA), we noticed that the response of earthworms to CNFs at 100 mg/kg showed a more significant deviation from the unexposed group. This was mainly determined by inhibiting antioxidant activity in the seminal vesicle, biochemical biomarkers assessed in muscle and intestine, and histomorphometric muscle biomarkers from earthworms exposed to CNFs at 100 mg/kg. Thus, we demonstrate that CNFs increase the parasite load of Monocystis sp. of adult L. terrestris earthworms and induce biochemical and histopathological changes, especially at 100 mg/kg. Our results point to the additional impact these nanomaterials can have on the health of earthworms, signaling the need for greater attention to their disposal and ecotoxicological effects on soil organisms., Competing Interests: Declaration of competing interest We confirm that there are no known conflicts of interest associated with this work, and there has been no significant financial support for this work that could have influenced its outcome. Furthermore, we ensure that the manuscript has been read and approved by all named authors and that there are no other persons who satisfied the criteria for authorship but are not listed. We further confirm that all have approved the order of authors listed in the manuscript of us. Due care has been taken to ensure the integrity of the work., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The growing use of synthetic chemical compounds/substances in vector control of mosquitoes, associated with their adverse effects on the environment and non-target organisms, has demanded the development of eco-friendly alternatives. In this context, this study aimed to evaluate the larvicidal action of different cellulose microcrystalline (CMs) concentrations and investigate their toxicity mechanisms in Culex quinquefasciatus fourth instar larvae as a model species. Probit analysis revealed that the median lethal concentrations (LC 50 ) for 24 h and 36 h exposure were 100 and 58.29 mg/L, respectively. We also showed that such concentrations induced a redox imbalance in the larvae, marked by an increase in the production of reactive oxygen species (ROS) and thiobarbituric acid reactive substances (TBARS), as well as a reduction in the activity of superoxide dismutase (SOD) and catalase (CAT). Furthermore, different alterations in the external morphology of the larvae were associated with the ingestion of CMs. On the other hand, exposure of adult zebrafish (Danio rerio) to LC 50 24h and LC 50 36h for seven days did not induce any behavioral changes or alterations mutagenic, genotoxic, biochemical, or in the production of cytokines IFN-γ and IL-10. Thus, taken together, our study demonstrates for the first time that the use of CMs can constitute a promising strategy in the control of C. quinquefasciatus larvae, combining insecticidal efficiency with an "eco-friendly" approach in the fight against an important mosquito vector of several human diseases., Competing Interests: Declaration of competing interest We confirm that there are no known conflicts of interest associated with this work, and there has been no significant financial support for this work that could have influenced its outcome. Furthermore, we ensure that the manuscript has been read and approved by all named authors and that there are no other persons who satisfied the criteria for authorship but are not listed. We further confirm that all have approved the order of authors listed in the manuscript of us. Due care has been taken to ensure the integrity of the work., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The resistance to insecticides among insects, including mosquitoes and agricultural pests, and the impact of these compounds' environmental risks and health issues have motivated the proposition of eco-friendly alternatives. Thus, we aimed to explore the potential use of Desmostachya bipinnata for the biosynthesis of TiO 2 NPs and evaluate their larvicidal and pupicidal activity of target (Aedes aegypti and Spodoptera litura) and acute toxicity in non-target organisms (Toxorhynchites splendens and Eisenia fetida), at distinct concentrations, after 24 h of exposure. The characterization of the biosynthesized TiO 2 NPs was carried out by FT-IR, XRD, SEM, and EDX analysis. Under the UV-vis spectrum analysis, a sharp peak was recorded at 200 to 800 nm, which indicated the production of TiO 2 NPs by the plant extract. The SEM analysis revealed that the synthesized TiO 2 NPs were spherical with a diameter of 36.4 nm and were detected in the XRD spectrum analysis related to the TiO 2 NPs. The highest percentage of mortality recorded at 900 μg/mL was 96 % and 94 % in the 2nd instar of A. aegypti and S. litura larvae, respectively, and exhibited the LC 50 and LC 90 values 5 of 458.79 and 531.01 μg/mL, respectively. The biosynthesized TiO 2 NPs showed concentration-dependent increased pupal lethality for both A. aegypti and S. litura. We also observed increased detoxification enzyme activity (α esterase, β esterase, and glutathione-S-transferase) of A. aegypti and S. litura exposed to different concentrations of biosynthesized TiO 2 NPs as histopathological changes in the midgut region of these animals. On the other hand, the mortality rate of non-target organisms (T. splendens and E. fetida) was lower when exposed to TiO 2 NPs, compared to the high lethality induced by synthetic pesticides (cypermethrin and monocrotophos for E. fetida; and cypermethrin and temphos for T. splendens). Thus, our study provides pioneering evidence on the potential use of D. bipinnata-mediated TiO 2 NPs for controlling mosquito vectors and agricultural pest management., Competing Interests: Declaration of competing interest We confirmed no known conflicts of interest associated with this work, and there has been no significant financial support for this work that could have influenced its outcome. Furthermore, we assure you that the manuscript has been read and approved by all named authors and that there are no other persons who satisfied the criteria for authorship but are not listed. Due care has been taken to ensure the integrity of the work., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The use of vegetal species for gold nanoparticles (AuNPs) biosynthesis can constitute an alternative to replacing the extensive use of several hazardous chemicals commonly used during NPs synthesis and, therefore, can reduce biological impacts induced by the release of these products into the natural environment. However, the "green nanoparticles" and/or "eco-friendly nanoparticles" label does not ensure that biosynthesized NPs are harmless to non-target organisms. Thus, we aimed to synthesize AuNPs from seaweed Gracilaria crassa aqueous extract through an eco-friendly, fast, one-pot synthetic route. The formation of spherical, stable, polycrystalline NPs with a diameter of 32.0 nm ± 4.0 nm (mean ±SEM) was demonstrated by UV-vis spectroscopy, field emission scanning electron microscopy, and high-resolution transmission electron microscopy, energy-dispersive X-ray and X-ray diffraction measurement, and Fourier-transform infrared spectroscopy analysis. In addition, different phytocomponents were identified in the biosynthesized AuNPs, using Gas Chromatography-Mass Spectrometry (GC-MS). However, both G. crassa aqueous extract and the biosynthesized AuNPs showed high ecotoxicity in Anopheles stephensi larvae exposed to different concentrations. Therefore, our study supports the potential of seaweed G. crassa as a raw material source for AuNPs biosynthesis while also shedding light on its ecotoxicological potential, which necessitates consideration of its risk to aquatic biota., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Entomopathogenic fungi are feasible and effective against the agricultural pest. In the current research we investigated the bioactive comparison of two widely accepted entmopathogens (Beauveria bassiana (Bals.) Vuill. and Metarhizium anisopliae, (basionym)) against the Spodoptera litura (Fab.) through the assessment of larval tolerance and regulation of antioxidants and non-target impact on the earth worm, E. eugeniae, along with commercial pesticides. The entomopathogenic fungus exposure resulted in the modification of the levels of detoxification enzymes as well as significant increases in catalase and superoxide dismutase activity after exposure to the entomopathogenic fungus. Bioassay results showed that B. bassiana and M. anisopliae displayed larval mortality against third and fourth instars. Correspondingly, sub-lethal concentrations of B. bassiana showed development impairment as compared to M. anisopliae. Gut-histology revealed that mycotoxins dosage (4 × 10 5 ) showed significant changes in the midgut tissues as compared to control larvae. The non-target screening through artificial soil assay on the earth worm E. eugeniae, with mycotoxins B. bassiana (5 × 10 8 conidia/ml/kg) and M. anisopliae (5 × 10 8 conidia/ml/kg) showed less toxicity as compared to Monocrotophos (10 ppm/kg). Current results suggest that the fungal mycotoxins of M. anisopliae and B. bassiana significantly reduce the development of lepidopteran pests, while having only lesser impact on beneficial earthworms., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Dengue and malaria are significant mosquito-borne diseases that are rapidly spread worldwide, mainly in temperate countries. Pteridophytes were identified to be a significant source of novel mosquitocidal agents. The present research was to explore the eco-friendly larvicides from methanol extracts of ferns, viz., Actiniopteris radiata, Adiantum caudatum, Cheilanthes swartzii, Hemionitis arifolia and Lycopodium clavatum. The larvicidal potential of the extracts screened using larvae of dengue vector Aedes aegypti (III and IV instar) and malarial vector Anopheles stephensi (III and IV instar), showed 10-100% mortality rates. Biosafety assessment was made on embryos of Danio rerio and Artemia nauplii. The phyto-constituents of the methanol extract of A. radiata leaves were identified through gas chromatography-mass spectrometry (GC-MS). Methanolic leaf extracts of A. radiata, A. caudatum and C. swartzii exhibited larvicidal activity against III and IV instar larvae of Ae. aegypti (LC 50 : 37.47, 74.51 and 152.38 and 67.58, 95.89 and 271.46 ppm) and An. stephensi (LC 50 : 70.35, 112.12 and 301.05 and 113.83, 175.30 and 315.19 ppm), respectively. The GC-MS of the methanol extract of A. radiata leaves revealed the presence of 7 phyto-components among which, Carbamic acid, phenyl-, (2-Nitrophenyl) methyl ester (1), Benzoic acid, 3- methylbenzoate (2) and 4-(benzylimino)- 1,4-dihydro-1-(p-toluoylmethyl) pyridine (3) were dominant. Biosafety assessment of methanol extract of A. radiata leaves on embryos of Danio rerio (Zebra fish) and Artemia nauplii (micro crustacean) revealed that there were no destructive or teratogenic effects. To conclude, the larvicidal activity and insignificant toxicity to non-target aquatic organisms of A. radiata leaves makes it a potential and environment safe biocontrol agent against dengue and malarial vectors., (Copyright © 2018. Published by Elsevier Inc.)

Resistance to treatments with Temephos or plant derived oil, Pb-CVO, between a field collected Wild Strain (WS) and a susceptible Laboratory Strain (LS) of Ae. aegypti were measured. The Temephos (0.1mg/L) showed the greatest percentage of mosquito mortality compared to Pb-CVO (1.5mg/L) in LS Ae. aegypti. However, WS Ae. aegypti was not significantly affected by Temephos (0.1mg/L) treatment compare to the Pb-CVO (1.5mg/L). However, both strains (LS and WS) when treated with Pb-CVO (1.5mg/L) displayed steady larval mortality rate across all instars. The LC 50 of Temephos was 0.027mg in LS, but increased in WS to 0.081mg/L. The LC 50 of Pb-CVO treatment was observed at concentrations of 0.72 and 0.64mg/L for LS and WS strains respectively. The enzyme level of α- and β-carboxylesterase was reduced significantly in both mosquito strains treated with Pb-CVO. Whereas, there was a prominent deviation in the enzyme ratio observed between LS and WS treated with Temephos. The GST and CYP450 levels were upregulated in the LS, but decreased in WS, after treatment with Temephos. However, treatment with Pb-CVO caused both enzyme levels to increase significantly in both the strains. Visual observations of the midgut revealed cytotoxicity from sub-lethal concentrations of Temephos (0.04mg/L) and Pb-CVO (1.0mg/L) in both strains of Ae. aegypti compared to the control. The damage caused by Temephos was slightly less in WS compared to LS mosquito strains., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Mosquito vector control is facing a number of important and timely challenges, mainly due to the rapid development of pesticide resistance and environmental concerns. In this scenario, screening of botanical resources for their mosquitocidal activity may offer effective and eco-friendly tools against Culicidae vectors. Culex quinquefasciatus Say (Diptera: Culicidae) is a vector of lymphatic filariasis and of dangerous arboviral diseases, such as West Nile and St. Louis encephalitis. In this study, the chemical composition of five essential oils obtained from different plants, namely Pinus nigra J.F. Arnold var. italica (Pinaceae), Hyssopus officinalis L. subsp. aristatus (Lamiaceae), Satureja montana L. subsp. montana (Lamiaceae), Aloysia citriodora Palau (Verbenaceae) and Pelargonium graveolens L'Hér (Geraniaceae), was investigated by GC-MS analysis. Furthermore, it was evaluated their acute toxicity on larvae of C. quinquefasciatus. Then, the most effective oils were selected, in order to focus on the potential synergistic and antagonistic effects, testing them in binary mixtures on C. quinquefasciatus larvae. Results showed that the higher effectiveness was obtained by S. montana subsp. montana essential oil (LC 50 =25.6μL·L -1 ), followed by P. nigra var. italica (LC 50 =49.8μL·L -1 ) and A. citriodora (LC 50 =65.6μL·L -1 ), while the other essential oils showed LC 50 values higher than 90μL·L -1 . The larvicidal effectiveness can be enhanced by preparing simple binary mixtures of essential oils, such as S. montana+A. citriodora (ratio 1:1), which showed higher larvicidal toxicity (LC 50 =18.3μL·L -1 ). On the other hand, testing S. montana+P. nigra (1:1) an antagonistic effect was detected, leading to a LC 50 (72.5μL·L -1 ) higher than the LC 50 values calculated for the two oils tested separately. Overall, our results add useful knowledge to allow the employ of synergistic essential oil blends as effective, cheap and eco-friendly mosquito larvicides., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Aedes aegypti Linn is one of the most important mosquito species. The vectors are responsible for causing deadly diseases like dengue and dengue hemorrhagic fever. Several chemical pesticides used to control these dengue vectors caused severe toxic significances on human health and other non-target beneficial insects. Therefore the current investigation has been made to access the bio-efficacy of the crude seed extracts of T. chebula against the dengue vector Ae. aegypti. The GC-MS analysis of crude seed extracts of T. chebula identified nine chemical compounds with major peak area in the 1,2,3-Benzenetriol (61.96%), followed by Tridecanoic acid (09.55%). Ae. aegypti larvae showed dose dependent mortality rate was observed between the treatments. Prominent protection rate at greater concentrations of 100ppm and moderate protection at 75 and 50ppm was observed in the repellent assay. Lethal concentration (LC 50 and LC 90 ) of fourth instar larvae of Ae. aegypti was observed in 138 and 220ppm concentration respectively. Similarly, the seed extracts showed 100% adulticidal activity at the concentration of 400ppm at 30min of exposure time. Phytochemicals present in the seed extracts of T. chebula significantly affects the major portions of the midgut tissues of Ae. aegypti at the concentration of 100ppm. The toxicological evaluation of seed extracts also proved non-toxic towards the A. bouvieri and Tx. splendens aquatic predatory insects. Hence, the present result suggest that bio-rational plant derived T. chebula could be incorporated in the dengue vector control and have no adverse effects on non-target beneficial insects., (Copyright © 2016 Elsevier Inc. All rights reserved.)

The current study investigated the toxic effect of the leaf extract compound andrographolide from Andrographis paniculata (Burm.f) against the dengue vector Ae. aegypti. GC-MS analysis revealed that andrographolide was recognized as the major chemical constituent with the prominent peak area compared with other compounds. All isolated toxic compounds were purified and confirmed through RP-HPLC against chemical standards. The larvicidal assays established at 25ppm of bioactive compound against the treated instars of Ae. Aegypti showed prominent mortality compared to other treated concentrations. The percent mortality of larvae was directly proportional to concentration. The lethal concentration (LC50) was observed at 12ppm treatment concentration. The bioactive andrographolide considerably reduced the detoxifying enzyme regulations of α- and β- carboxylesterases. In contrast, the levels of GST and CYP450 significantly increase in a dose dependent manner. The andrographolide also showed strong oviposition deterrence effects at the sub-lethal dose of 12ppm. Similarly, the mean number of eggs were also significantly reduced in a dose dependent manner. At the concentration of 12ppm the effective percentage of repellency was greater than 90% with a protection time of 15-210min, compared with control. The histopathology study displayed that larvae treated with bioactive andrographolide had cytopathic effects in the midgut epithelium compared with the control. The present study established that bioactive andrographolide served as a potential useful for dengue vector management., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Botanical insecticides may provide alternatives to synthetic insecticides for controlling Spodoptera litura (F.) and they are target specific, biodegradable, and harmless to mammals. Eight natural chemical compounds with larvicidal activity were identified from fraction F6 of C. guianensis flower extract. Probit analysis of 95% confidence level exposed an LC50 of 223ppm against S. litura third instar larvae. The growth and development of S. litura was affected in sub-lethal concentrations of fraction F6 (50, 100, 150 and 200ppm) compared to controls. Similarly nutritional indices values decreased significantly compared to controls. Fraction F6 also damaged the gut epithelial layer and brush border membrane (BBM). This study also resolved the effects of toxicity to non-target earthworm treated with fraction F6 and chemical pesticides (monotrophos and cypermethrin) and the results showed that fraction F6 had no harmful effect on E. fetida. Further, fraction F6 was eluted and sub fractions F6c (50ppm) showed high mortality against S. litura third instar larvae. Octacosane from fraction F6c was established and confirmed using IR spectrum and HPLC. The time of retention of fraction F6c was confirmed with the octacosane standard. Fraction F6 of C. guianensis extract caused dose-dependent mortality towards S. litura. Octacosane in fraction F6c was establish to be the prominent chemical compound associated with causing mortality but other compounds present in the fraction F6 were shown to be associated with changes in development of S. litura at low dosages. S. litura at low dosage. Therefore, these findings suggest that octacosane may be one of the major insecticidal compounds affecting S. litura survival., (Copyright © 2016 Elsevier Inc. All rights reserved.)

The effects of two different neem products (Parker Oil and Neema) on mortality, food consumption and survival of the brown planthopper, Nilaparvata lugens Stål (BPH) (Homoptera: Delphacidae) were investigated. The LC(50) (3.45 ml/L for nymph and 4.42 ml/L for adult in Parker Oil treatment; 4.18 ml/L for nymph and 5.63 ml/L for adult in Neema treatment) and LC(90) (8.72 ml/L for nymph and 11.1 ml/L for adult in Parker Oil treatment; 9.84 ml/L for nymph and 13.07 ml/L for adult in Neema treatment) were identified by probit analysis. The LC(90) (equal to recommended dose) was applied in the rice field. The effective concentration of both Parker Oil and Neema took more than 48 h to kill 80% of the N. lugens. Fourth instar nymph and adult female N. lugens were caged on rice plants and exposed to a series (both LC(50) and LC(90)) of neem concentrations. Nymph and adult female N. lugens that were chronically exposed to neem pesticides showed immediate mortality after application in laboratory experiment. The quantity of food ingested and assimilated by N. lugens on neem-treated rice plants was significantly less than on control rice plants. The results clearly indicate the neem-based pesticide (Parker Oil and Neema), containing low lethal concentration, can be used effectively to inhibit the growth and survival of N. lugens.

Treatment of Dysoxylum pure triterpenes 3beta,24,25-trihydroxycycloartane and beddomei lactone to the rice leaffolder (RLF), Cnaphalocrocis medinalis (Guenée) (Lepidoptera: Pyralidae), resulted in prolonged larval duration and reduced larval weight. In leaf cut choice assay and topical application experiments, beddomei lactone and 3beta,24,25-trihydroxycycloartaneto showed strong antifeedant and growth inhibitor activity against fourth instar larvae of C. medinalis. Also average leaf consumption was decreased (89%) by the treatment of the two terpinoids when compared with controls. Number of eggs laid by the female (fecundity) was decreased and oviposition deterrence index was increased due to the treatment. This result further shows that the pure triterpenes of Dysoxylum act as both an antifeedant and chronic toxin to the rice leaffolder larvae.

The effect of azadirachtin (AZA), a tetranortriterpene from neem, on the mortality, acetylcholinesterase (AChE) activity, and the development of the ovaries of female brown planthopper (BPH), Nilaparvata lugens (Stål) was tested in laboratory experiments. The lethal concentrations were determined and applied topically to the adult female BPH (LC(50)=0.47 ppm and LC(90)=0.96 ppm). The treated insects exhibited toxic symptoms with a dose-dependent mortality. The LC(50) concentrations were tested against AChE activity of the BPH. The results indicate that AZA significantly inhibits the activity of AChE only at the high dose (P<.0001) compared with control. Adult females that were exposed to AZA showed a significant reduction in weight (23%, 40%, and 64% for 0.1, 0.25, and 0.5 ppm, respectively). Fecundity was also significantly reduced in AZA treatments compared to the control. Histological study of ovary sections revealed abnormalities in follicular epithelial cells due to AZA treatment.