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Showing 71 results for Toxicity


Volume 0, Issue 0 (1-2024)
Abstract

Controlling insect pests through nano-based formulation of chemicals is one of the newly applied methods in IPM programs; however, the probable side impacts of nano-pesticides on non-target organisms need to be evaluated. In this study, deltamethrin and matrine were encapsulated with polyethylene glycol (PEG) and chitosan (Cs), respectively, and their toxicity were investigated against Habrabracon hebetor Say using the contact method. According to the scanning electron microscopy (SEM), spherical nanoparticles for both formulations were observed. The average hydrodynamic nanoparticle diameters for deltamethrin and matrine were 65 and 70.5 nm. The LC50 values were 254.48, 334.90, 760.31 and 1021 mg L-1 in PEG-encapsulated deltamethrin, commercial deltamethrin, Cs-encapsulated matrine, and commercial matrine, respectively. Exposing to the LC30 of the commercial and nano-encapsulated deltamethrin significantly prolonged the total pre-adult period. The adults of H. hebetor in PEG-encapsulated deltamethrin treatment had the lowest longevity compared to other treatments and control. Furthermore, the sublethal exposure to the PEG-based nanoformulation of deltamethrin and commercial deltamethrin resulted in a significant reduction of the intrinsic rate of natural increase (rm) (0.159 and 0.168 day-1, respectively). Same trend was observed for the gross reproductive rate (GRR), net reproductive rate (R0), and finite rate of increase (λ) of the parsitoid. Our findings indicate that the negative side effects of commercial and nano-based formulations of deltamethrin on H. hebetor should be considered in IPM programs.
 

Volume 1, Issue 2 (6-2012)
Abstract

Certain compounds of plants such as essential oils, with insecticidal properties have been considered as alternatives to chemical pesticides for pest control. This study reports the fumigant toxicity of Citrus reticulata Blanco (Rutaceae) peel essential oils against stored-product insect pest, red flour beetle, Tribolium castaneum Herbst (Tenebrionidae) adults. Experiment was carried out at 27 ± 1 °C and 60 ± 5 % relative humidity in darkness. Experimental concentrations were 15, 22, 31, 45, and 63 μl/l air tested on adult (1-7 days old) insects after 24 and 48 h of exposure. Results indicated that essential oils from C. reticulata had fumigant tocxicity effects against this stored pest. LC50 values were 38.2 and 35.6 μl/l air at 24 and 48 h after exposure of T. castaneum adults respectively. The essential oils of Citrus reticulata fruit peels at the highest dose of 63 μl/l air caused 76.6 % and 79 % mortality of insects after 24 and 48 hours of exposure, respectively. Mortality of T. castaneum increased with both increase in concentration of C. reticulata oils as well as exposure time of treated insects. These results suggest the potencial of C. reticulata oil as a control agent against T. castaneum.  

Volume 1, Issue 2 (6-2013)
Abstract

Formalin is a common disinfectant and therapeutic agent in fisheries-related activities. Considering large variation in susceptibility of different species to formalin toxicity, it is necessary to determine its toxicity and safety margins in different species, separately. Therefore, to investigate formalin acute toxicity and safety margins on Caspian roach, an experiment was conducted in 1g Caspian roachs Rutilus rutilus caspicus. Fish were exposed to 0, 30, 40, 45, 50, 55, 60, 70, 100, 150, 200, 250, 300 and 400 ppm formalin and mortality was recorded after 0.5, 1, 12, 24, 48, 72 and 96h. 0.5-96 h LC50 values were 49-246 ppm. The lowest observed effect concentrations (LOEC) were found to be 40-150 ppm at different periods. No observed effect concentrations (NOEC) were 30-100 ppm at different periods. According to regression model for NOEC versus time, concentrations of 88.4, 80.3, 51.2 and 40.1 ppm are suggested as the maximum concentrations for 0.5, 1, 12 and 24 h bath treatment, respectively. Results showed the recommendations for formalin safety in the literatures are not applicable and valid for Caspian roach. Such differences could be due to species or experimental differences which should be taken into account before treating.

Volume 1, Issue 3 (9-2013)
Abstract

Acute toxicity (96h-LC50) of potassium permanganate (PM) was determined for Caspian kutum Rutilus frisii kutum at two size classes (1 and 3 g). Static renewal method was used. Fish were exposed to different concentrations of PM and mortality was recorded thereafter, until 96 h. Exposed fish showed behavioral stress indicators. 96h-LC50 was calculated to be 3.204 (3.147-3.260) mg/L for small fish and 3.460 (3.393-3.528) mg/L for large fish. Safe concentration for small and large fish was calculated to be 0.003-0.320 and 0.003-0.342 mg/L, respectively. No Observed Effect Concentration (NOEC) and Lowest Observed Effect Concentration (LOEC) were 2.6 and 2.8 mg/L for small and 2.8 and 3.0 mg/L for large fish. Results indicated that Caspian kutum is susceptible to PM toxicity; although less than many tested species. Likewise, toxicity of PM significantly decreases with increase in fish weight. Higher tolerance in large fish compared to small fish might be as a result of increased stress resistance and higher quality of these fish.

Volume 1, Issue 3 (9-2013)
Abstract

In order to understand the importance of particle size and agglomeration for nano-eco-toxicological studies in aquatic environments, the acute toxicity of two different types (suspended powder and colloidal) of silver nanoparticles (AgNPs) were studied in alevin and juvenilerainbow trout. Fish were exposed to each type of AgNPs at nominal concentrations of 0.032, 0.1, 0.32, 1, 3.2, 10, 32, and 100 mg/L. Lethal concentrations (LC) were calculated using a Probit analysis. Some physical and chemical characteristics of silver nanoparticles were determined. In the case of colloidal form, particles were well dispersed in the water column and retained their size; but in the case of suspended powder, particles were agglomerated to large clumps and precipitated on the bottom. In alevins, the calculated 96 h LC50 values were 0.25 and 28.25mg/L for colloidal and suspended powder AgNPs respectively. In the case of juveniles, the 96h LC50 of colloidal form was 2.16mg/L, but suspended powder did not caused mortality in fish even after 21 days. The results showed that both in alevin and juvenile stages, colloidal form is much toxic than suspended powder; this shows increase of nanoparticles size due to agglomeration, will reduce the toxicity. Silver nanoparticles are toxic materials and their release into the water environment should be avoided.

Volume 1, Issue 3 (10-2014)
Abstract

Background: Age-related differences in the ethoxyresorufin O-deethylase (EROD) activity of CYP1A1 and its inducibility in rats may determine the toxic potential of acetaminophen.  This study was carried out to compare the effects of acetaminophen (APAP) and β-naphthoflavone (βNF) on CYP1A1 activity in young and adult rats. Methods: For this purpose, young and adult rats (n = four / group) were treated with different doses of APAP. Likewise groups of young and adult rats were treated with a single dose of β-naphthoflavone (βNF, 67 mg / kg b.w). EROD was measured in microsomal fraction using resorufin as the substrate. Results:The results showed that a single i. p. injection of APAP (25 mg / kg B.W.) failed to alter liver microsomal EROD in young and adults. Whereas, in adults treated with 250 and 450 mg APAP / kg B.W, liver CYP1A1 was elevated to about 45 and 60% respectively. The rate of CYP1A1 induction in young rats with single dose of APAP (450 mg/kg B.W) was approximately 32%. Induction in CYP1A1 was noticed 4 h after APAP injection and returned to normal levels in 24 h. The inducibility of CYP1A1 in rats treated with a toxic dose of APAP was comparable to the data obtained from animals treated βNF, 67 mg / kg b.w. Conclusion: These results together with our previous reports indicate a similar pattern of changes in CYP1A1 in both the age-groups treated with toxic doses of APAP may suggest that the inducible CYP1A1 can equally contribute to protection against liver damage in young and adult rats.

Volume 2, Issue 1 (3-2013)
Abstract

The potato tuber moth (PTM), Phthorimaea operculella Zeller (Lepidoptera: Gelechiidae), is an important pest of potato and other solanaceous plants. It is cosmopolite and oligophage that exists in most countries where potatoes are grown. Because of chemical treatment adverse effects, there is a necessity to find safe alternatives to synthetic insecticides. So, medicinal plants are promising since they are safe, inexpensive and effective. In this direction, potato tubers were dipped in 1 ml of 5% methanolic extracts of fumitory, licorice, lavender and oregano. The percentage of first larval penetration to tubers and oviposition-preference of mentioned medicinal plants was investigated on PTM. Subsequently, fumigant toxicity of essential oils of basil, european pennyroyal, lavender, mint and savory were investigated on P. operculella. Treated potato tubers by methanolic extract of lavender elicited the lowest percentage (19.3) of first larval penetration. Studying of oviposition-preference demonstrated that the largest number of eggs were laid on control and fumitory with 28 and 10 eggs after three days, respectively. Probit analysis of essential oils showed that the most effective oil was savory which exhibited LC50 value on adults of PTM equivalent to 0.048 µL/L air.  

Volume 2, Issue 1 (3-2013)
Abstract

The essential oils of aerial parts of three medicinal plants Artemisia khorassanica Podl., Rosmarinus officinalis L. and Mentha longifolia L. were isolated by hydrodistillation and investigated for their toxicity and repellency against Tribolium confusum Jacquelin du Val. at 27 ± 1 ºC and 60 ± 5% RH in darkness. The mortality of the adults increased with concentration from 185 to 1111 μl/l air and with exposure time from 9 to 24 h. A concentration of 185 μl/l air and exposure time of 24 h was sufficient to obtain nearly 100% kill of the adults in all of the three essential oils tested. At the highest concentration (1111 μl/l air) R. officinalis oil caused 15% mortality for an exposure time of 6-h. whilst, the oil of A. khorassanica resulted in 1% mortality at the same exposure time. The oil of A. khorassanica at 1111 μl/l air caused 81% mortality for 12-h exposure time. No significant differences were observed between the lethal time (LT50) values at essential oil concentrations of 741 and 1111 μl/l air. For 24-h exposure time, the LC50 values of A. khorassanica, R. officinalis and M. longifolia essential oils were estimated to be 22.45, 22.14 and 39.96 μl/l air respectively. Based on LC50 values, adults of T. confusum showed similar susceptibility to the A. khorassanica and R. officinalis oils, but M. longifolia oil proved to be less toxic. In contrast to their low fumigant properties, the essential oil of M. longifolia had significantly higher repellency to T. confusum adults than did the other two.  
, Ahmad Gharaei, , ,
Volume 2, Issue 2 (9-2013)
Abstract

The acute toxicity and histopathology of Schizothorax zarudnyi  (2±0.2 g body weight)exposed to diazinon was assessed statically in 22±2°C, following the OECD Guideline. The 96h LC50 value of diazinon for the fish was 14.70 mg/l, therefore making its MAC value 1.47 mg/l in natural waters. According to the table of insecticides sorting, the toxicity of diazinon was low for S. zarudnyi. Some clinical symptoms and abnormal reactions such as lordosis and neural paralytic syndrome, losing the balance and swimming in a half circle, expressive pigmentation mainly on the dorsal part and block of respiration movements in the fish exposed to this pesticide were observed. Histopathological evidence from the tissues of liver, kidney, gill, and gut revealed vascular tissue of the liver, sinusoids, hepatocytes vacuole degeneration, shrinkage and degeneration of some urinary cells, dilatation of Bowman's space, pycnotic nucleus of some kidney cells and increase in the number of interstitial kidney cells. Complications, such as hyperemia, telangiectasia, edema, shrinkage, clubbing and adhesion to the secondary gill filaments were also observed.

Volume 2, Issue 3 (7-2016)
Abstract

Background: This study was performed to determine antifungal activity of silver nanoparticles (nano-Ag) compared to voriconazole on clinical and standard strains of Aspergillus fumigatus.
Materials and Methods: Inhibitory potency of nano-Ag was determined using microtiter broth dilution method. Susceptibility tests were performed against A. fumigatus isolated from BAL (bronchoalveolar lavage) of patients who suffered from respiratory problems and compared with the strain (ATCC: 204305) by broth dilution antifungal susceptibility test of filamentous fungi approved by the Clinical and Laboratory Standards Institute M38-A. In addition, cytotoxicity effect of silver nanoparticles was studied on epithelial cell line by MTT assay.
Results: From 60 BAL samples the following strains were isolated; A. flavus (n=21), A. niger (n=3), and A. fumigatus (n=1). The minimum inhibitory concentration (MIC90) values of nano-Ag were 0.25 and 0.5 μg.mL-1 for standard strain and clinical isolates respectively. The  Minimum Fungicidal Concentration (MFC) values of nano-Ag were 0.5 and 1 μg.mL-1for standard strain and clinical isolates respectively. MIC90 values of voriconazole were 0.125 and 0.25 μg.mL-1 for standard strain and clinical isolate respectively. The MFC values of voriconazole were 0.25 and 0 μg.mL-1 for standard strain and clinical isolates respectively. Silver nanoparticles exhibited low cytotoxicity in 0.25 μg.mL-1 concentration.
Conclusion: Our results showed high antifungal activity of silver nanoparticles against Aspergillus isolates. Furthermore, the availability of a wide form of nano-Ag structures can be considered as novel agents to decrease fungal burden in medical application.

Volume 2, Issue 4 (3-2019)
Abstract

In this study, phenolic compounds-coated ZnO@HAP nanocomposite (Ph.ZnO@HAP) was synthesized and used to improve the physical and chemical properties of chitosan hydrogel for biological application. At first, the phenolic compounds were extracted from walnut green hulls. The synthesis of Ph.ZnO@HAP nanocomposite was performed with the assistance of extracted phenols using a hydrothermal method. Chitosan hydrogel was also prepared using NaHCO3 at 37°C. Hybrid hydrogels based on chitosan and Ph.ZnO@HAP nanocomposite were prepared in a similar way and then characterized by fourier-transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM). The antioxidant property, cytotoxicity, and osteogenesis of hybrid hydrogels were measured using DPPH radical scavenging method, MTT, and alkaline phosphatase enzyme assay, respectively. The FTIR spectra, FESEM images, EDX spectrum, and Zeta potential data showed that Ph.ZnO@HAP nanocomposites synthesized successfully with rod-like morphology, phenolic compounds coated on the surface and a negative particle surface charge. The results of DPPH experiment showed that the antioxidant property of the nanocomposite material increased in a concentration-dependent manner. The FESEM images of chitosan hybrid hydrogels with different concentrations of embedded Ph.ZnO@HAP nanocomposite showed that hybrid hydrogels have a more uniform porous structure, compared to the chitosan hydrogel. Moreover, by an increase in the nanocomposite concentration in the structure of hybrid hydrogels, the antioxidant property augmented. The results of the biological studies showed that the cytotoxicity of hybrid hydrogels on osteoblast-like cells (Saos-2) is lower than that of chitosan hydrogel. Also, hybrid hydrogels showed the higher potential in induction of osteogenesis than chitosan hydrogels.
 

Volume 3, Issue 1 (3-2014)
Abstract

Microcerotermes diversus Silvestri (Isoptera: Termitidae) is the most economically destructive wood pest in structures in Khuzestan province (Iran). Chemicals such as essential oils and plant extracts that are compatible with the environment and have high potential to be used in integrated pest management programs are extremely important resources. This study evaluated contact and digestive toxicity of Eucalyptus camaldulensis Dehneh. (Myrtaceae)essential oil in no-choice and choice bioassays and feeding inhibition trials on M. diversus. Concentrations of the essential oil ranged from 0.3 to 1.6%. The results of the choice tests and feeding inhibition trial showed that the essential oil could act as a repellent at 0.7% concentration. Concentrations used in these tests resulted in mortality of termites, and a direct relationship between concentration and mortality was observed. The essential oil also increased the mortality of termites at concentrations higher than 0.7%. Termite feeding decreased with increase in concentration. Due to the ability of termites to choose the untreated filter-paper in the choice trial, values of LT and LC, were higher than in no-choice trials. The highest effects of Eucalyptus essential oil (≈100% mortality) was obtained by the concentration 1.6%. Overall, this study reveals that Eucalyptus essential oil may be suggested as an effective toxicant with suitable contact and digestive toxicity on M. diversus.  

Volume 3, Issue 2 (6-2014)
Abstract

Essential oils are volatile mixtures of hydrocarbons with diverse functional groups. In the current study the effect of essential oils from five medicinal plants including Zataria multiflora and Nepeta cataria (Lamiaceae), Tagetes minuta and Artemisia sieberi (Asteraceae), and Trachyspermum ammi (Apiaceae) were analyzed using GC-mass spectrometry. The toxicity of these plant essential oils against the adult stage of the cabbage aphid, Brevicoryne brassicae L. (Hemiptera: Aphididae) was studied using a fumigant assay.GC/Mass analysis revealed that the main essential oils varied between species. The most abundant components in N. cataria, Z. multiflora, T. ammi, T. minuta and A. sieberi were 4a-α, 7-β, 7a-α-nepetalactone (76.8%), carvacrol (62.1%), γ-terpinene (27.1%), limonene (13.0%) and artemisia ketone (48.0%) respectively. The fumigant assays showed that all of these essential oils were toxic to B.brassicae in a dose-dependent manner. The essential oils of N. cataria at 126, 63, 31, 16, 8, and 3 μl L-1 air caused 94, 76, 52, 46, 36, and 24% mortality within 24 hours, respectively. The same trend was seen when essential oils of the other plants were tested against B. brassicae. These plant essential oils have great potential to be used in integrated pest management especially in greenhouses or other closed systems.

Volume 3, Issue 2 (4-2001)
Abstract

Cotton (Gossypium hirsutum L. cv. Varamin ) an important industrial crop of Iran, is grown in 300,000 ha, with an average seed -cotton yield of 1750 Kg.ha-1. The main obstacle in the way of increasing average cotton yield is imbalanced fertilizer use. Along with urea and triple super phosphate, cotton growers also need K, Mg, Zn, Fe, Mn, Cu, and B, so these elements’ critical levels should be determined in cotton fields. Field experiments were conducted in 12 different fields in 1997 to determine critical levels of Fe, Zn, and B in soil, and to study the effects of these micronutrients on the yield and quality of cotton in Varamin region. The experiment design was a randomized complete block one (RCB) with four treatments and three replications. Treatments were; NPK, NPK+Fe, NPK+Zn, and NPK+B. Iron was applied as FeEDDHA (20 kg.ha-1), Zn as zinc sulfate (40 Kg.ha-1), and B as boric acid (20 Kg. ha-1) prior to planting. Average seed cotton yield, lint yield, seed index, and boll weight increased significantly by adding Fe, Zn, and B. In a cotton field with higher soil B concentrations, cotton yield decreased with B fertilizer. Critical levels of Fe, Zn, and B were determined based on Cate-Nelson graphical and analysis of variance methods. In graphical method critical levels of Fe, Zn, and B were 4.8, 1.1, and 1.0 mg.Kg-1 soil, respectively, while on the basis of analysis of variance method, these levels were 5.5, 1.1, and 1.3 mg.kg-1 soil, respectively. In one field, boll shedding decreased by Zn and Fe treatments but was not affected by B addition. Iron to Zn ratio in cotton leaves increased at Fe treatment and decreased in Zn treatments. Boron treatment increased B content of leaves. Furthermore, zinc sulfate decreased B toxicity in the cotton leaves. In short, applying micronutrients increased quality and yield of cotton in Varamin region.

Volume 4, Issue 4 (9-2018)
Abstract

Aims: Antiviral activity and effect of methanol and diethyl ether extracts from different parts of sea cucumber (Holothuria leucospilota) against HIV-1 were assessed on human oral epidermoid carcinoma cells (KB) and Human embryonic kidney 293T cells (HEK293T).
Materials & Methods: Sea cucumber was collected at a depth of 10-30 m (Persian Gulf). Extracts were prepared by diethyl ether and methanol solvents. The antiviral activity of each extract was evaluated by inhibition of single-cycle HIV-1 (SCR HIV-1) p24 Core antigen production in HeLa cells and cellular toxicity of different extracts were assessed, using a cell proliferation XTT kit.
Findings: Antiviral activity of each extract showed that some concentrations were able to inhibit the replication of HIV-1. Diethyl ether extract of body wall with 2.79 TI index displayed the highest antiviral activity as well as less effect.
Conclusion: This study showed that crude extracts of Holothuria leucospilota, especially methanol and diethyl ether extracts of digestive organs and body wall and antiviral activity, respectively.


Volume 5, Issue 1 (3-2016)
Abstract

New sources of botanical pesticides in the management of Sitotroga cerealella (Olivier) infesting rice grains are indispensable in farmers’ quest towards achieving maximum protection of their rice produce. In this study, the efficacy of root and stem bark of Cleistopholis patens as an insecticidal agent against S. cerealella was investigated at 28 ± 2 ºC and 75 ± 6% relative humidity. Moths were exposed to contact and fumigant toxicity test at 0.5-2.5 g/20 g of paddy rice and mortality was assessed at 24, 48, 72 and 96 hours post-treatment respectively. Generally, moth exposed to root powders of C. patens showed higher mortality values (contact: 10 - 93%; fumigant: 13 - 100%) than their counterpart exposed to stem powder (contact: 6.67 - 78%; fumigant: 10 - 95%). Also, lethal doses (LD50 and LD95) revealed that lower doses of C. patens root powder resulted in higher mortality of S. cerealella when compared to that of stem powder. The only exception was observed in LD95 values of stem (6.54 g / 20 g of paddy rice) and root (6.76 g / 20 g of paddy rice) powder of fumigant toxicity test. Both powders of C. patens also significantly reduced adult emergence in treated grains when compared to control. This study showed that powders of stem and root bark of C. patens would provide a much desired wherewithal to synthetic insecticides in the management of S. cerealella infesting rice grains in Nigeria.

Volume 5, Issue 2 (6-2016)
Abstract

Tetranychus turkestani is one of the most important pests of greenhouse plants in the southern provinces of Iran. Several benefits of using essential oils over chemical pesticides make them appropriate for IPM programs. Contact and fumigant toxicity of the essential oils of Foeniculum vulgare and Citrus limon against the spider mite and its predator, Orius albidipennis were investigated under laboratory conditions. Contact toxicity experiments were conducted at six concentrations, (0, 50, 100, 300, 800 and 2000 ppm) of each essential oil on the mature and immature life stages of the pest, and mortalities were recorded 72 h after exposure. In fumigant toxicity trials, LC50 values of the essential oils were determined on different developmental stages of T. turkestani and O. albidipennis. At 800 and 2000 ppm, both essential oils had high contact toxicity on the eggs, 2nd instar nymphs and adults of T. turkestani, while the same concentrations caused less mortality on O. albidipennis. No significant phytotoxicity of the essential oils was observed. The mortality rates of T. turkestani and O. albidipennis increased as concentration was increased. Also, the 2nd instar nymph of T. turkestani was more sensitive to contact application of the essential oils than other developmental stages. In the fumigant toxicity bioassay, LC50 values of the essential oil derived from F. vulgare on the egg, 2nd instar nymph and adult of T. turkestani were 16.08, 7.98 and 14.06, and the values for C. limon essential oil were 11.6, 9.86 and 11.52 µl × l-1air, respectively. The highest fumigant toxicity was observed against the 2nd instar nymphs of the mite. Fumigant toxicity of the essential oils was lower against O. albidipennis than against T. turkestani. This data suggests that the essential oils of these plants have the potential of being employed in the IPM programs of T. turkestani in greenhouse crops, especially cucumber.

Volume 5, Issue 2 (6-2016)
Abstract

Plant essential oils and their constituents are recognized as proper alternatives to fumigants. Thymus daenensis Celak is one of these plants that have medicinal properties and is endemic to Iran. The essential oil was isolated by hydrodistillation from dry leaves using a modified clevenger-type apparatus and the chemical composition of the oil was assessed via GC and GC-MS. Fourteen compounds (100% of the total composition) were identified. Thymol (57.4%), carvacrol (9.8%), β-caryophyllene (6.9%), γ-terpinene (6.7%) and p-cymene (6.3%) were found to be the major compounds of the essential oil. The fumigant toxicity of the essential oil was tested against 1-3 days old adults of Callosobruchus maculatus (F.) and Sitophilus granarius (L.) at 27 ± 1 °C and 65 ± 5% R. H. in darkness. The mortality of adults was tested at different concentrations (28.12, 40.62, 53.12 and 65.62 µl/l air) and different exposure times. At the highest concentration (65.62 µl/l air), T. daenensis oil caused 90 and 60% mortality with a 3 h exposure on C. maculatus and S. granarius, respectively. Based on LC50 values, C. maculatus (4.22 µl/l air) was significantly more susceptible than S. granarius (6.55 µl/l air). These results show the efficacy of T. daenensis oil for stored-products protection.

Volume 5, Issue 3 (9-2016)
Abstract

In the present study, seven indigenous, widely distributed plants of Meghalaya, namely, Pinus kesiya Royle (Pinaceae), Lantana camara Linn. (Verbenaceae), Litsea cubeba Lour. (Lauraceae), Gaultheria fragrantissima Wall. (Ericaceae), Mikania micrantha Kunth.(Asteraceae), Ambrosia artemisiifolia Linn.(Asteraceae) and Eupatorium riparium Regel (Asteraceae) were screened for their larvicidal and antifeedant activity against fourth instar larvae of the cotton bollworm, Helicoverpa armigera (Hübner) under laboratory conditions. The crude extracts of all the seven plants demonstrated a dose dependent increase in bioactivity. However the bioactivity of four plants namely, L. camara, G. fragrantissima, L. cubeba and P. kesiya was significantly higher (p ≤ 0.05) than the negative (solvent) control and extracts of A. artemisiifolia, E. riparium and M. micarantha. Methanol extract of L. camara caused highest oral toxicity with larval mortality ranging between 27.77% and 53.33% across the test concentration (0.25%, 0.5% and 1% w/v) while extract of G. fragrantissima demonstrated the highest feeding deterrence with reduction in larval feeding by50.92% and 70.61% at 0.1% and 0.5% respectively. Crude extract of L. cubeba leaves demonstrated high oral toxicity and feeding deterrence while extract of the needles of P. kesiya showed moderate level of oral toxicity as well as feeding deterrence at the highest tested concentration. Phytochemical analysis of the extracts of these four plants, revealed the presence of five different classes of phytocompounds each of which is known to have deleterious effect on insect pests.Thus it may be concluded that four out of the seven plants possess insecticidal property and can be further investigated for the development of a potent botanical insecticide.

Volume 5, Issue 3 (9-2016)
Abstract

Tomato leaf miner, Tuta absoluta Meyrick (Lepidoptera: Gelechiidae), is one of the most destructive pests of tomato in many parts of the world including Iran. Field studies were conducted to determine the short and long term effects of Bacillus thuringiensis var Kurstaki (Bt), azadirachtin (AZ), a mix of AZ + Bt, and indoxacarb, as a current chemical insecticide, on T. absoluta larvae. Also, effects of the insecticides were studied on the coexisting generalist predators, Coccinella septempunctata L., Chrysoperla carnea Stephens and Syritta sp. Sampling of T. absoluta and its coexisting generalist predators were performed 1 day before treatment (DBT) and one, 5, 8, 14 and 19 days after treatment (DAT). The results indicated significant short term effect of indoxacarb on the pest larvae. Indoxacarb reduced T. absoluta density and damages. Bt, AZ and mixture of them significantly suppressed the larval density at 19 DAT and caused significant reduction in leaf, stem and fruit damage. The highest long term effect on the pest abundance and damage were observed in Az + Bt caused 100% reduction in fruit and foliage damage compared to the control. The highest and lowest adverse effects on C. carnea, C. septempunctat and Serrita sp. were observed in indoxacarb and Bt treatments, respectively. Findings of this study imply that the mixture of Az + Bt has the highest selective toxicity on the pest and the lowest effect on its coexisting generalist predators.  

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