Respective LC50 Values Research Articles

Toxicity Effect Test of Matoa (Pometia pinnata) Plant Fractions as Raw Materials for Anticancer Drugs

Background:The prevalence of cancer in Indonesia increases every year. Medical treatments such as chemotherapy, surgery, and radiation require significant costs with considerable side effects. Therefore, there is a need for chemopreventive agents from natural sources such as plants. One plant with potential as a chemopreventive agent is the matoa tree (Pometia pinnata), which is empirically used to treat suppurating wounds.Objectives: This research aims to test the toxicity of leaf and stem bark fractions of matoa using shrimp larvae Artemia salina Leach. Methods: The parameter for this study is the LC50 value. The extraction method involves successive maceration using solvents based on increasing polarity, starting with n-hexane, chloroform, ethyl acetate, and methanol. Phytochemical screening is conducted using colour tests, and toxicity is assessed through the brine shrimp lethality test. The research indicates that all fractions of matoa leaves and stem bark are toxic with respective LC50 values for leaf fractions: n-hexane (394.8 µg/mL), chloroform (244.3 µg/mL), ethyl acetate (180.6 µg/mL), and methanol (303.2 µg/mL). Stem bark fractions exhibit LC50 values in the order of n-hexane (203.9 µg/mL), chloroform (244.3 µg/mL), ethyl acetate (144.8 µg/mL), and methanol (58.3 µg/mL). Conclusions: All fractions fall into the toxic category and have the potential as raw materials for anti-cancer drugs.

Surface and composition effects on the biphasic cytotoxicity of nanocomposites synthesized using leaf extracts

The Malus sylvestris L. (LE1), Pinus sylvestris L. (LE2), and Sorbus aucuparia L. (LE3) leaves` extracts were used for the synthesis of silver (Ag) nanocomposites containing different amounts of silver chloride (AgCl), silver metal (Agmet), and silver phosphate (Ag3PO4). These nanocomposites were capped with the organic functional groups in the leaf extract. Notably, the nanocomposites caused biphasic cytotoxic response on cells; first attributed to the inhibition of cell growth and second to cell death. The nanocomposites were biocompatible with normal embryonic kidney (HEK293) cells in the cytotoxic range for cancer cells. ▪ [25(±1) °C synthesis] nanocomposites exhibited the highest cytotoxicity towards HeLa (lethal concentration- LC50 value of 11.4 μg mL−1) and A549 (LC50 value of 14.7 μg mL−1) after 24-h incubation and its efficiency was shown also for the more resistant MCF-7 and MDA-MB-231, however, their respective LC50 values were larger. For the HeLa cell line, this designed ▪ nanocomposite exhibited an LC50 value similar to the effective concentration (EC50) value of Cisplatin and about 3 times larger than Doxorubicin. ▪ nanocomposite contained Ag3PO4 in the composite and P on the surface, higher AgCl content, smaller crystallite size of all nanoparticle phases, and carbon-rich oxygen-deficient surface compared to all other nanocomposites.

Toxicity of Elytraria Acaulis (L. F.) Lindau (Acanthaceae) to the Larvae of Vector Mosquitoes

Synthetic pesticides, which are non-biodegradable and have detrimental effects on the environment, non-targeted organisms, and human health, are often used to control mosquitoes. This situation fostered and prompted the creation of substitutes utilizing natural products like phytoextracts and phytochemicals. The current study was set out to determine the toxicity of leaf extracts from Elytraria acaulis on the early third instar larvae of Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus at doses of 31.5, 62.5, 125, 250, 500 and 1000mg/L at 24 and 48 hours of exposure. All extracts, with the exception of aqueous, demonstrated potent larvicidal effectiveness with 100% larval death in all the three studied vector mosquitoes after 48 hours. The ethanol extract showed the maximum larvicidal activity and 100% larval mortality in Aedes aegypti after 24 hours, and its respective LC50 values against Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus were 31.98, 560.29, 603.8108mg/L and 20.43, 46.13 and 60.08mg/L after 24 and 48 hours. The treated larvae exhibited extremely restless behaviour, including wiggling, sinking, floating, slowness, paralysis, sinking to the bottom of the glass beaker, and ultimately death. Qualitative phytochemical study of Elytraria acaulis leaves revealed the presence of alkaloids, flavonoids, glycosides, phenolics, saponins, steroids, tannins, terpenes, and terpenoids. The ethanolic extract GC-MS examination identified main phytocompounds, including imidazole, imidazolidinone, phytol, phytol acetate, octacosane, thymol 1-thiocarbonylimidazolide and methoxyacetic acid to determine the larvicidal mechanism of action and the cause of larval death. It is quite exciting to note, based on the results of the current investigation, that Elytraria acaulis leaf extracts, particularly ethanol extract, demonstrated good larvicidal efficacy. The present study documents the first report on the effectiveness of Elytraria acaulis ethanolic leaf extract against the larvae of Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus.

Essential oils of the ginger plants Meistera caudata and Conamomum vietnamense: chemical compositions, antimicrobial, and mosquito larvicidal activities.

The current study describes the chemical identification, antimicrobial, and mosquito larvicidal activities of essential oils from Meistera caudata and Conamomum vietnamense, growing in Vietnam. Essential oils were extracted from the leaves and rhizomes, and characterized by the GC-FID/MS (gas chromatography-flame ionization detection/mass spectrometry) analysis. Monoterpenes (33.1-89.2 %) were the main chemical class found in these oils. β-Pinene (30.8 %) and α-pinene (23.8 %) were two major compounds in M.caudata leaf oil. C.vietnamense leaf and rhizome essential oils were dominated by 1,8-cineole (47.9-62.0 %) and limonene (10.3-16.2 %). With the same MIC (minimum inhibitory concentration) value of 25 μg/mL, C.vietnamense leaf and rhizome essential oils strongly inhibited the growth of Gram-positive bacteria Staphylococcus aureus ATCC 29213 and Bacillus subtilis ATCC 6501, respectively. For 24 and 48-h treatments, C.vietnamense leaf essential oil strongly controlled the growth of mosquito Aedes aegypti with the respective LC50 values of 7.67 and 6.73 μg/mL, and the respective LC90 values of 13.37 and 10.83 μg/mL. In the same manner, C.vietnamense rhizome essential oil also showed strong mosquito larvicidal activity against Aedes albopictus with the LC50 values of 12.37 and 12.00 μg/mL, and the LC90 values of 20.56 and 18.58 μg/mL, respectively. C.vietnamense essential essential oils containing a high amount of 1,8-cineole are generally better than M.caudata essential essential oils in both two biological assays.

Exploring the in vitro anticancer activities of Re(I) picolinic acid and its fluorinated complex derivatives on lung cancer cells: a structural study.

Fifteen rhenium(I) tricarbonyl complexes of the form fac-[Re(N,O')(CO)3(X)], where N,O'-bidentate ligand = 2-picolinic acid (Pico); 3,5-difluoropyridine-2-carboxylic acid (Dfpc); 3-trifluoromethyl-pyridine-2-carboxylic acid (Tfpc) and X = H2O; pyrazole (Pz); pyridine (Py); imidazole (Im); and methanol (CH3OH) were synthesized using the '2 + 1' mixed ligand approach with an average yield of 84%. The complexes were characterized using the following spectroscopic techniques: IR, 1H and 13C NMR, UV/Vis, and single-crystal X-ray diffraction. The effect of the fluorine atoms on the backbone of the N,O'-bidentate ligand was investigated and a trend was noticed in the carbonyl stretching frequencies: with Pico < Tfpc < Dfpc. The in vitro biological screening on Vero (healthy mammalian), HeLa (cervical carcinoma) and A549 (lung cancer) cells revealed one toxic complex, fac-[Re(Pico)(CO)3(H2O)], with respective LC50 values of 9.0 ± 0.9, 15.8 ± 4.9 (SI = 0.570) and 20.9 ± 0.8 (SI = 0.430) μg/mL. As a result, it can be used as a positive control drug of toxicity.

​Biotin Inhibitors, Avidin and Streptavidin: Their Influence on Lethality, Growth and Survival of Callasobruchus maculatus (Chrysomelidae: Coleoptera)

Background: C. maculatus, the most important and cosmopolitan pest, severely attacking several stored pulses leading to weight loss, market value, as well as the germination potential of the infested grains. The present study was conducted to know the effect of biotin inhibitors, avidin and streptavidin on lethality, growth and survival of Callasobruchus maculatus. Methods: The experiment was conducted in the laboratory of Department of Entomology, Agricultural College, Bapatla during 2017-18. Bio assays were conducted against C. maculatus with biotin binding proteins’ (BBP’s) viz., avidin and streptavidin in comparison with spinosad by pellet feeding method. Similarly the effect of BBP’s on growth development of C. maculatus was also studied. Result: Based on bioassay studies, the LC50 for avidin and streptavidin were 14.733 and 11.192 ppm while LC90 was 76.031 and 86.134 ppm, respectively. The growth and development of C. maculatus was studied at approximately the respective LC25, LC50, LC75, LC80 and LC90 values of avidin and streptavidin. Avidin and streptavidin incorporated pellets when fed to it, avidin at concentration of ≥ 75 ppm was found effective by recording lesser number of eggs (≤ 9 eggs), delayed day of first adult emergence (≥ 53 days), maximum development period ( greater than 68 days), minimum adult emergence (≤ 13%), lower growth index (≤ 0.2) and minimum weight loss (≤ 16%) and streptavidin at concentrations of ≥ 75 ppm recorded comparatively minimum eggs (≤ 7 eggs), prolonged day of first adult emergence (≥ 66 days), maximum development period (≥ 82 days), minimum adult emergence (≤ 13%), lower growth index of ≤ 0.16 and minimum pellet weight loss of ≤ 12% respectively.

Formulation of Clitoria ternatea Leaves-mediated Silver Nanoparticles to Control Aedes aegypti Larvae

Introduction: Global rise in the Aedes-borne diseases and harmful effects of synthetic insecticides has diverted research to explore secondary metabolites in plants as mosquito control agent in the form of nanoparticles. Current study investigated Clitoria ternatea-mediated nanoparticles against Aedes aegypti. Methods: The aqueous and hexane leaf extracts of C. ternatea were assayed against Ae. aegypti early fourth instars. The extract-mediated silver nanocomposites (AgNCs) were synthesized after optimizing the volume and concentration of silver nitrate solution. The synthesis was tracked by the colour change of reaction mixture from pale yellow to dark brown followed by monitoring with UV-Visible spectroscopy and Dynamic Light Scattering. Results: The biosynthesis of 3 mM, 4 mM and 5 mM AgNCs was traced at 438, 401 and 407 nm, respectively. The average particle size distribution ranged from 34.62 to 60.64 nm and polydispersity index was 0.6-0.7. The 24 h larval exposure with aqueous and hexane leaf extracts demonstrated respective LC50 values of 53.057 and 42.179 mg/L, which decreased significantly on larvicidal assay with NCs. The 5mM AgNCs showed the maximum efficiency with LC50 of 10.317 mg/L after 24 h. Scanning and transmission electron microscopy images demonstrated a spherical, poly-dispersed structure with diameter in the 1-27 nm range. The assays against non-targets; Moina and Cyclops ascertained the eco-safety of NCs. Conclusion: The study demonstrated the C. ternatea leaf extract as possible effective mosquito nano-larvicide, alternate to traditional insecticides. Field studies, which could not be held due to the current pandemic, would further ascertain the possible use of these NCs against Aedes larvae.

Effect of Lipopeptide-Loaded Chitosan Nanoparticles on Candida albicans Adhesion and on the Growth of Leishmania major.

Cyclic lipopeptides produced by Bacillus species exhibit interesting therapeutic potential. However, their clinical use remains limited due to their low stability, undesirable interactions with host macromolecules, and their potential toxicity to mammalian cells. The present work aims to develop suitable lipopeptide-loaded chitosan nanoparticles with improved biological properties and reduced toxicity. Surfactin and bacillomycin D lipopeptides produced by Bacillus amyloliquefaciens B84 strain were loaded onto chitosan nanoparticles by ionotropic gelation process. Nanoformulated lipopeptides exhibit an average size of 569nm, a zeta potential range of 38.8mV, and encapsulation efficiency (EE) of 85.58%. Treatment of Candida (C.) albicans cells with encapsulated lipopeptides induced anti-adhesive activity of 81.17% and decreased cell surface hydrophobicity (CSH) by 25.53% at 2000µg/mL. Nanoformulated lipopeptides also induced antileishmanial activity against Leishmania (L.) major promastigote and amastigote forms at respective IC50 values of 14.37µg/mL and 22.45µg/mL. Nanoencapsulated lipopeptides exerted low cytotoxicity towards human erythrocytes and Raw 264.7 macrophage cell line with respective HC50 and LC50 values of 770µg/mL and 234.56µg/mL. Nanoencapsulated lipopeptides could be used as a potential delivery system of lipopeptides to improve their anti-adhesive effect against C. albicans cells colonizing medical devices and their anti-infectious activity against leishmania.

The insecticidal activity of recombinant nemertide toxin α-1 from Lineus longissimus towards pests and beneficial species

The nemertide toxins from the phylum Nemertea are a little researched family of neurotoxins with potential for development as biopesticides. Here we report the recombinant production of nemertide α-1 (α-1), a 65-residue inhibitor cystine knot (ICK) peptide from Lineus longissimus, known to target insect voltage-gated sodium channels. The insecticidal activity of α-1 was assessed and compared with the well characterised ICK venom peptide, ω-atracotoxin/hexatoxin-Hv1a (Hv1a). α-1 elicited potent spastic paralysis when injected into cabbage moth (Mamestra brassicae) larvae; conferring an ED50 3.90 μg/larva (10.30 nmol/g larva), followed by mortality (60% within 48 h after 10 μg injection). By comparison, injection of M. brassicae larvae with recombinant Hv1a produced short-lived flaccid paralysis with an ED50 over 6 times greater than that of α-1 at 26.20 μg/larva (64.70 nmol/g larva). Oral toxicity of α-1 was demonstrated against two aphid species (Myzus persicae and Acyrthosiphon pisum), with respective LC50 values of 0.35 and 0.14 mg/mL, some 6-fold lower than those derived for recombinant Hv1a. When delivered orally to M. brassicae larvae, α-1 caused both paralysis (ED50 11.93 μg/larva, 31.5 nmol/g larva) and mortality. This contrasts with the lack of oral activity of Hv1a, which when fed to M. brassicae larvae had no effect on feeding or survival. Hv1a has previously been shown to be non-toxic by injection to the beneficial honeybee (Apis mellifera). By contrast, rapid paralysis and 100% mortality was observed following injection of α-1 (31.6 nmol/g insect). These results demonstrate the great potential of naturally occurring non-venomous peptides, such as α-1, for development as novel effective biopesticides, but equally highlights the importance of understanding the phyletic specificity of a given toxin at an early stage in the quest to discover and develop safe and sustainable pesticides.

Comparing the efficacy of nutmeg essential oil and a chemical pesticide against Musca domestica and Chrysomya albiceps for selecting a new insecticide agent against synantropic vectors

The insecticidal activity of Myristica fragrans (Houtt) essential seed oil, (Nutmeg) was evaluated against Musca domestica (Linnaeus) and Chrysomya albiceps (Wiedemann); both important infectious pathogenic disease vectors. The oil was extracted by distillation, and 21 components were identified during chemical analysis; principally β-pinene (26%), α-pinene (10.5%), Sabinene (9.1%) and γ-terpinen (8.5%). Insecticidal properties were identified through larvicide and adulticide tests. Using the immersion method, the oil at 5% was found to be very effective (90 ± 1%) against M. domestica larvae. The results for adulticide activity varied by fly species, dosage, time, and method of exposure. Topical application (on the insect thorax) was more toxic to C. albiceps, where the lethal concentration at 50% (LC50) was 2.02 ± 0.56, and 8.57 ± 2.41 for the common flies. When the insects were exposed to oil impregnated paper, the results were similar for M. domestica and C. albiceps adults with respective LC50 values of 2.74 ± 0.24, and 3.65 ± 0.48. Thus, the results demonstrated that M. fragrans oil presents insecticidal activity and can be used for control of Musca domestica and Chrysomya albiceps.

New Purinyl-Steroid and Other Constituents from the Marine Fungus Penicillium brefeldianum ABC190807: Larvicidal Activities against Aedes aegypti

Mosquitoes historically threatened human health; the major mosquito-related global health issues include malaria, dengue fever, yellow fever, and Zika, as well as several other vector-borne outbreaks. Here, the EtOAc extract of the mangrove sediment fungus Penicillium brefeldianum ABC190807 exerted larvicidal activities against the third instar larvae of Aedes aegypti with an LC50 of 0.089 mg/mL. One new purinyl-steroid (ergosta-4,6,8(14),22-tetraen-3-(6-amino-9H-purin-9-yl) (1)), along with six (2–7) known compounds, were isolated from the EtOAc extract of Penicillium brefeldianum ABC190807. Structures of the compounds were elucidated via 1D/2D NMR and HR-ESI-MS data. Respective spectral data were compared with those of known compounds. Among all compounds whose larvicidal activity against the third instar larvae of Aedes aegypti was evaluated, compounds 2 and 7 showed larvicidal activity with respective LC50 values of 0.452 and 0.337 mg/mL.

Physiological and reproductive fitness cost in Aedes aegypti on exposure to toxic xenobiotics in New Delhi, India

Aedes aegypti, is a well-known vector of dengue, Chikungunya and Zika at the global level. Primary use of pyrethroids as control interventions has caused the development of a considerable level of immunity in Ae. aegypti. The current study assessed the efficacy of a pyrethroid, ?-cypermethrin on the survival and various life parameters of Ae. aegypti. The larvicidal studies with ?-cypermethrin revealed the respective LC50 and LC90 values as 0.26526 mg/L and 0.60211 mg/L. The impact of LC50 level was assessed on the growth and life attributes; such as gonotrophic cycle, egg development, hatchability, development and survival of immature stages, adult longevity, reproduction rate and generation time; of fourth instar of susceptible (S) and ?-cypermethrin-exposed population (E). The exposed population showed diminished fitness as compared to the susceptible population. The individual female fecundity in susceptible population was recorded as 79.6 with 61.6% hatchability rate as compared to the 28 eggs/female and 25% hatchability in the exposed population. The mean egg hatch time in S strain increased by 2-fold in E strain. The proportion of immature survival observed in S strain was 0.88 for fourth instar to pupa (P/I), 0.94 for pupa to adult (A/P) and an overall 0.83 for fourth larva to adult (A/I), which respectively reduced to 0.32, 0.86 and 0.27 in E strain of Ae. aegypti. Likewise, the net reproductive rate, birth rate and death rate were significantly (p &lt; 0.05) higher in S than in E strain. This study demonstrates the negative impact of ?-cypermethrin on the physiological and reproductive fitness of Ae. aegypti.

Activity against Meloidogyne incognita of volatile compounds produced during amendment of soil with castor bean cake

Summary Incorporation of castor bean cake into the soil results in the emission of four main compounds: skatole, γ-decalactone, 4-methylphenol and phenol. The toxic effects of these compounds on the life cycle of Meloidogyne incognita were studied here. Only phenol did not reduce hatching of M. incognita second-stage juveniles (J2) at any of the concentrations tested. The other compounds reduced J2 hatching by 42.1 to 59.3% at the highest concentrations. When J2 were immersed in Tween 80® solutions of each compound, at their respective LC50 values and inoculated into soil with tomato plants, reductions in the numbers of galls (48.5-69.3%) and eggs (42.8-62.5%) were observed in comparison with the control; this result was similar to that of carbofuran. The highest reductions in the numbers of galls (21.8-88.5%) and eggs (49.6-98.9%) occurred with all compounds when the highest concentration (500 mg l−1) was applied to the substrate at the moment of J2 inoculation. Volatile compounds of γ-decalactone and skatole failed to cause J2 immobility or mortality. However, phenol caused 95.8% and 4-methylphenol caused 100% mortality. With fumigation, the highest concentration (1000 mg (l substrate)−1) of any tested compound reduced gall numbers at a similar rate to the nematicide dazomet (98.7-100%) and reduced egg numbers (87.1-99.7%). The volatile compounds skatole, γ-decalactone, 4-methylphenol and phenol have a nematicidal effect on the life cycle of M. incognita and alter its pathogenic behaviour on the plant.

Laboratory bioassay of soil insecticides against grubs of Brahmina coriacea (hope) (Scarabaeidae: Coleoptera) in Himachal Pradesh

Comparative bioefficacy of six insecticides viz. chlorantraniliprole, bifenthrin, clothianidin, thiamethoxam, imidacloprid and chlorpyriphos is reported in laboratory evaluation against grubs of Brahmina coriacea (Hope) through dip treatment. The LC50 values of chlorantraniliprole for the three instars of grubs of B. coriacea were found to be 70.65, 213.30 and 226.1 ppm, while for bifenthrin, these were 100.20, 259.90 and 337.10 ppm respectively. Similarly, the LC50 values of clothianidin for the three instars of grubs were 139.51, 266.12 and 348.30 ppm. Imidacloprid produced 50 per cent kill (LC50) at a concentration of 156.12, 415.58 and 622.04 ppm in the three instars of grubs, and for thiamethoxam the respective LC50 values were 205.89, 477.31 and 626.67 ppm. Chlorpyriphos was found to be least toxic among the tested chemicals. It produced 50 per cent kill of the three instars of grubs at concentrations of 222.60, 506.92 and 556.72 ppm, respectively.

One-pot synthesis of silver nanocomposites from Achyranthes aspera: An eco-friendly larvicide against Aedes aegypti L.

Objective: To formulate silver nanocomposites from Achyranthes aspera leaf extracts and evaluate its larvicidal activity against Aedes aegypti. Methods: The silver nanocomposites were synthesized from Achyranthes aspera leaf extracts. The process was optimized and traced through UV-visible and photon correlation spectroscopy. The larvicidal potential of silver nanocomposites of Achyranthes aspera leaf extracts was assessed against the early fourth instars of Aedes aegypti and three non-target organisms. Furthermore, the most effective and eco-safe nanocomposite was characterized by different biophysical techniques including scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform-infrared spectroscopy (FT-IR). Results: The formulated silver nanocomposites exhibited efficient larvicidal efficacy against Aedes aegypti. Bioassay with silver nanocomposites formulated using different AgNO 3 concentrations (3, 4, and 5 mM) revealed respective LC50 values of 37.570, 6.262 and 1.041 μg/mL; 5.819, 1.412 and 0.489 μg/mL; and 5.519, 1.302 and 0.267 μg/mL after 24, 48 and 72 h. The silver nanocomposites with 4 mM AgNO3 were selected for characterization. SEM and TEM analysis revealed spherical, poly-dispersed structure with varied diameters of 1-25 nm. The XRD analysis established the crystalline and face-centred-cubic structure of silver nanocomposites with the maximum peak at a 2θ value of 37.42°. The EDX pattern showed the presence of Ag, O and C in the nanocomposites in their order of weight%. The FT-IR displayed visibly distinct peaks in different ranges demonstrating the intricacy of silver nanocomposites. In addition, the lethal concentrations of silver nanocomposites of Achyranthes aspera leaf extracts against Aedes aegypti larvae were non-toxic to non-target organisms including Gambusia affinis, Daphnia magna and Moina macrocopa. Conclusions: Silver nanocomposites synthesized with leaf extract of Achyranthes aspera provide a cost-effective and eco-safe alternative to conventional insecticides, and can be utilized as a potent mosquito nano-larvicide.

Variations in chemotypes patterns of Tunisian Rosmarinus officinalis essential oils and applications for controlling the date moth Ectomyelois ceratoniae (Pyralidae)

The study explores variations of Rosmarinus officinalis essential oils chemotypes collected from eight sites from north Tunisia and their fumigant toxicity against fifth instar larvae of the date moth Ectomyelois ceratoniae. GC and GC–MS analyses revealed 1,8-cineole (44.5–57.88%), (+)- camphor (9.27–18.99%), α-pinene (9.18–3.66%), borneol (tr- 13.21%) and camphene (3.15–4.69%) as major compounds of the oils. Three chemotypes namely 1,8-cineole/camphor/α-pinene; 1,8-cineole/camphor and camphor/1,8-cineole were identified with the first one being predominant. Results of the fumigant bioassays indicated that all rosemary essential oils showed considerable larvicidal toxicities. Respective LC50 values were ranged between 14.02 and 171.11 μL/L air. Moreover, oils from Korbous and Fernana sites exhibited highest toxicities and mortalities reached, respectively, 60.78 and 100% at 90 µL/L air after 30 days of exposure. In addition, oils inhibits adult emergence with inhibition rates ranged between 22% and 100%. This work supports the interest of industrial use of rosemary essential oil as raw materials and its application as environmentally friendly insect control agent after the necessary toxicological considerations.

Toxicity and Oxidative Stress Induced in Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) Treated with Some Insecticides

Integrated pest management of herbivorous pests relies on combining bio-insecticides and chemical insecticides for a satisfactory population control. The present study focused on evaluating the comparative toxicity of five insecticides, with different modes of action, against third and fifth instar larvae of Spodoptera littoralis and their influence on extent of oxidative stress in insect via detecting vitamin C content as well as measuring the activity of phenol oxidase (PO), catalase (CAT), peroxidase (POX), glutathione-S-transferase (GST) antioxidant enzymes compared to control. The results revealed that emamectin benzoate and indoxacarb were the most potent insecticides among the selected insecticides, based on their respective LC50 values. Thiacloprid, indoxacarb and emamectin benzoate significantly reduced Vitamin C content. Almost all treatments significantly increased PO activity. Only emamectin benzoate and Bacillus thuringiensis significantly induced POX activity. Indoxacarb and emamectin benzoate increased CAT activity in both instar larvae, whereas thiacloprid and indoxacarb decreased GST activity. In conclusion, emamectin benzoate and indoxacarb were the most potent insecticides. Activity of oxidative stress biomarkers upon insecticidal pressure has showed variable response.

Effects of three common pesticides on survival, food consumption and midgut bacterial communities of adult workers Apis cerana and Apis mellifera

The acute and chronic toxicity of 3 common pesticides, namely, amitraz, chlorpyrifos and dimethoate, were tested in Apis mellifera and Apis cerana. Acute oral toxicity LC50 values were calculated after 24 h of exposure to contaminated syrup, and chronic toxicity was tested after 15 days of exposure to 2 sublethal concentrations of pesticides. The toxicity of the tested pesticides to A. mellifera and A. cerana decreased in the order of dimethoate > chlorpyrifos > amitraz. A. mellifera was slightly more sensitive to chlorpyrifos and dimethoate than A. cerana, while A. cerana was more sensitive to amitraz than A. mellifera. Chronic toxicity tests showed that 1.0 mg/L dimethoate reduced the survival of the two bee species and the food consumption of A. mellifera, while 1.0 mg/L amitraz and 1.0 mg/L chlorpyrifos did not affect the survival or food consumption of the two bee species. The treatment of syrup with amitraz at a concentration equal to 1/10th of the LC50 value did not affect the survival of or diet consumption by A. mellifera and A. cerana; however, chlorpyrifos and dimethoate at concentrations equal to 1/10th of their respective LC50 values affected the survival of A. cerana. Furthermore, intestinal bacterial communities were identified using high-throughput sequencing targeting the V3V4 regions of the 16S rDNA gene. All major honey bee intestinal bacterial phyla, including Proteobacteria (62.84%), Firmicutes (34.04%), and Bacteroidetes (2.02%), were detected. There was a significant difference in the microbiota species richness of the two species after 15 days; however, after 30 days, no significant differences were found in the species diversity and richness between A. cerana and A. mellifera exposed to 1.0 mg/L amitraz and 1.0 mg/L chlorpyrifos. Overall, our results confirm that acute toxicity values are valuable for evaluating the chronic toxicity of these pesticides to honey bees.

Larvicidal activity of selected essential oil in synergized combinations against Aedes aegypti

This study was conducted to attain an alternate plant essential oil (EO) based mosquito larvicide against the dengue vector Aedes aegypti. Here three plants were selected based on their local availability, safety and insecticidal properties. EOs were extracted from Syzygium aromaticum (Myrtaceae) flower buds, fruits of Illicium verum (Schisandraceae) and Trachyspermum ammi (Apiaceae) by hydro-distillation and tested against Ae. aegypti larvae individually and in combinations to find synergistic interactions. Chemical constituent analysis of EOs was done by GC/MS/MS analysis and the main constituents in T. ammi were thymol (93.58%) and terpinen-4-ol (2.16%), in S. aromaticum eugenol 56.32% and caryophyllene 17.91% and in I. verum trans-anethole 53.05% and p-anisaldehyde 12.47%. The EOs from T. ammi, I. verum and S. aromaticum and their top components thymol, trans-anethole and eugenol exhibited larvicidal activity with LC50 values 39.48, 41.30, 66.90, 59.76, 50.19 and 60.89 mgL−1 respectively against Ae. aegypti larvae. The values for the co-toxicity factors for the binary combinations of the EOs were > 20 showing synergistic interactions among the binary mixtures. The respective LC50 values for the 1:1 binary combinations (S. aromaticum + I. verum), (S. aromaticum + T. ammi) and (I. verum + T. ammi) were 49.07, 48.54 and 27.67 mgL−1. β-cyclodextrin inclusion complex made with I. verum + T. ammi combination showed an LC50 value of 23.93 mgL−1. On the whole the outcome of this study draw attention to the capability of synergistic EO combinations to emerge as a safe and environment friendly effective larvicide to control Aedes mosquitoes.

Acute and subacute effects of drugs in embryos of Danio rerio. QSAR grouping and modelling

The final fate of many drugs is release into the natural aquatic environment. It is necessary to assess the toxicity caused by this situation and the associated concerns for human beings. Zebrafish (Danio rerio) is a common biomodel used to assess toxicity in aquatic environments. The zebrafish embryo toxicity test was selected to evaluate the acute toxicity of several drugs (diphenhydramine, gentamicin, tobramycin, enalapril and lidocaine) due to the lack of such information. Lethal and sublethal effects were detected, and the LC50 values of the drugs ranged from 11.0 mg/L to 422·102 mg/L. For all of the drugs tested, these values were higher than the concentrations found in the natural environment. Therefore, there was a low environmental toxicological risk. Nevertheless, teratogenic effects were also recorded when embryos of zebrafish were exposed to caffeine (control drug), diphenhydramine and lidocaine at lower concentrations than the respective LC50 values. Quantitative structure–activity relationship analysis was also performed to analyse these drugs and other chemicals with pharmaceutical uses as well as previous toxicological data in this vertebrate after 48 h of exposure. It is estimated that the partition coefficient, log P, is the main physicochemical property related to the ecotoxicological data and can be used for the development of a mathematical model.