جستجوی مقالات مرتبط با کلیدواژه « آفت کش » در نشریات گروه « گیاهپزشکی »

Ants are eusocial insects of the family Formicidae and are one of the most successful insects in number and diversity. Despite their favorable impact on the ecosystem, they are sometimes regarded as serious pests due to damage to agricultural products and construction facilities. Baiting is a suitable alternative to many traditional ant control methods. In the present study, the effect of oral toxicity of fipronil, imidacloprid and borax on Tapinoma karavaievi workers was evaluated under laboratory conditions at 72, 96 and 120 hours after treatment and then the survival rate of workers treated with the LC50 of the studied compounds was compared in two weeks. According to the results, the highest oral toxicity in all three-time points was related to fipronil, imidacloprid and borax, respectively. In addition, the evaluation of the effect of pesticides on the survival of workers showed a faster control of workers treated with the LC50 of fipronil (2.46 mg ai L-1) compared to imidacloprid (32.61 mg ai L-1) and borax (2654.4 mg ai L-1). The results showed that 90% effectiveness of fipronil and imidacloprid occurred on days 7 and 11 after treatment, respectively, and it seems that 90% effectiveness of borax will probably take place in the third week after treatment. In general, the current study showed that all three studied pesticides have sufficient potential to control workers and the selection of the most suitable pesticide depends on considering the pesticide concentration, strategy of control and attention to the side effects of pesticides.

Cabbage white, Pieris brassicae (L.) (Lepidoptera: Pieridae) is an important pest of cruciferous in Iran and the world. In this study, the effect of four insecticides; hexaflumuron, spinosad, abamectin and indoxacarb on cabbage white and its parasitoid Cotesia glomerata L. was investigated The LC50 values obtained from the analysis of probit as a result of the effect of different concentrations of hexaflumuron, spinosad, abamectin and indoxacarb on the 3rd instar larvae of P. brassicae after 72 hours were (0.213, 0.298, 0.30 and 0.434) ml/L, respectively. The LC50 values obtained from the same insecticides on eggs of P. brassicae after 7 days were (0.831, 0.440, 0.267 and 0.489) ml/l, respectively. The results of the same compounds effects on parasitoid after 7 days showed that hexaflumuron and indoxacarb are the most harmful and abamectin is the least harmful for this natural enemy. The results showed that the most effective insecticides on 3rd instar larvae of P. brassicae during 72 hours was hexaflumuron. In the study of parasitization of third instar larvae of cabbage white under the influence of different concentrations of hexaflumuron, spinosad, abamectin and indoxacarb in compared with control, results showed at low concentrations of all four insecticides, there is no significant difference between control and insecticides, but there was a significant difference in higher concentrations and the mean number of third instar larvae in the control treatment increased. According to the results of this study, hexaflumuron can be suggested as a low-risk compound for parasitoid and effective against this pest.

Pistachio is one of the most important agricultural products of the country.  It is extremely important and accounts for about 81 percent of the country's non-oil revenues. In this study, the degradation of two pesticides, metacystox and fenitrithion was investigated by ultraviolet radiation. These three pesticides are commonly used in a wide range in pistachio gardens in the country. One of the most important agricultural and plant protection tasks is to produce safe crops with residual pesticides below the MRL level. The aim of this study was to investigate the effect of UV radiation combined with the photocatalytic effect of titanium dioxide and hydrogen peroxide on the degradation of these two pesticides in pistachio products.The samples were extracted by LLE method and determinated by GC-MS. Exposur times were 30, 60,120 and 300 minutes.The results showed that the highest percentage of degradation of pesticides was related to metasystox and affected by uv / H2O2 at 38.5%. The optimum time in all trials was 300 min. UV irradiation alone at 300 min time on metasistox and fenitrothion in pistachio reduced the toxin by 24/2and 17/1, respectively.Experiments showed that degradation of the studied toxins was possible using UV irradiation and the destructive effect of UV on chemical structures was proved in experiments. Therefore, UV radiation in a specific dose can remove residues of pistachio pesticides. Combined with UV agents, hydrogen peroxide and titanium dioxide can more effectively remove contamination from agricultural products.

A Quantitative Structure–Activity Relationship (QSAR) study based on Genetic Algorithm  Multiple Linear Regressions (GA-MLR) were carried out for the prediction of the toxicity (logIC50) and the logarithm of octanol-water partition coefficient (logPow) of some carbamate derivatives as insecticides. The optimized conformation of compounds were obtained at HF/6-31G* level with Gaussian 98 software. Dragon software is used to calculate molecular descriptors. A data set of these compounds was randomly divided into 2 groups: training and test sets. The QSAR models were optimized using multiple linear regressions (MLR).The most relevant molecular descriptors were collected by Genetic Algorithm (GA) and backward regression. The best GA-MLR models are obtained using statistical parameters, such as squared correlation coefficient (R2), adjusted squared correlation coefficient (R2adj), root mean square error (RMSE) values for training and test sets. The best QSAR models are obtained based on the statistical parameters Leave-one-out (LOO) cross-validation, external test set, external validation parameters (Q2F1, Q2F2, Q2F3) and the concordance correlation coefficient (CCC) were used to quantify the predictive ability of GA-MLR models. The results showed that GA-MLR models could be used to predict the activities of carbamate derivatives.

Biological pesticides have advantages to chemicals that safety to non-target organisms is of the most important ones. Slugs are parasitized or preyed by several organisms such as nematodes. In this research, integrated management of grey slug Parmacella ibera was assessed by Phasmarhabditis hermaphrodita, Metaldehyde and Fericol in field conditions in Someh Sara, Guilan Province. The treatments included: untreated, P. hermaphrodita recommended dose, P. hermaphrodita recommended dose + Fericol, P. hermaphrodita ½ dose and P. hermaphrodita ½ dose +Metaldehyde ½ dose on P. ibera assessed based on the percent of dead slugs, mean percent of damaged leaves, the number of leaves with damage symptoms and the number of plants with damage symptoms. Results showed the highest percent of dead slugs in P. hermaphrodita ½ dose +Metaldehyde ½ dose. Mean percent of damaged leaves was not significantly different among P. hermaphrodita treatments along with Fericol and metaldehyde. Results indicated that P. hermaphrodita ½ dose + Metaldehyde ½ dose treatment had considerable effect in all parameters on pest control besides a decrease in the damage.

The orange Pulvinaria scale, Pulvinaria aurantii (Cockerell) is the most important pest of citrus in Mazandaran, Iran. The calculation of economic injury level is essential for the appropriate decision to Pest control. The economic injury level (EIL) of P. aurantii on Washington navel orange was studied during two years (2011 and 2012) in Sari (north of Iran). In the first year, six treatments of different densities of pest ovisacs (0, 1, 4, 7, 10 and 13) and each treatment with 8 replications and in the second year, five treatments (0, 5, 10, 15 and 20), each treatment with 7 replications on the leaves were evaluated in a completely randomized design (CRD). Economic injury level (EIL) was calculated as 133, 125, 110 and 131 ovisacs per branches with an average number of 7.1, 6.7, 5.9 and 7 fruits for the first generation of 2011 and 242, 228, 201, and 238 ovi sacs per branches with an average number 7.1, 6.68, 5.88 and 7.01 fruits for the first generation of 2012, as well as 203, 191, 168 and 200 ovisacs per branches with an average number 7.1, 6.68, 5.88 and 7.01 fruits for the second generation of 2012, for ethion, chlorpyrifos, buprofezin and diazinon pesticides, respectively.

The use of resistant plants in integrated pest management and its compatibilitywithchemicalcontrol measures has been emphasized in various studies. The effect of resistant cultivars on the efficacy of imidacloprid (SC 35%) was studied against eggs, nymphs and adults of the silver leaf whitefly, Bemisia tabaci (Gennadius) reared on Termus 14 (susceptible) and Okra (partially resistant) cotton cultivars under greenhouse conditions in 2013. Bioassays were conducted at 24±2°C, 65±5% R.H and a photoperiod of 16: 8 (L: D) using leaf- dipping method. The results indicated that mortality of all stages of B. tabaci was increased as a consequence of increase in the concentration of the insecticide. Toxicity of imidacloprid for all developmental stages of B. tabaci reared on partially resistant cultivar (Okra) was greater than those reared on Termus 14. The LC50 values of imidacloprid for the eggs, nymphs and adults reared on Termus 14 were 151.6 , 67.66 and 112.65 ppm, respectively. These values were determined for Okra as 135.78, 59.30 and 97.13 ppm, respectively. The results show a positive interaction between the use of partial resistant cotton cultivar to B. tabaci and imidacloprid. The results also show that the combined use of resistant plants and imidacloprid cause reduction of pesticide use to produce a given mortality rate. The results can be considered as the effective method for integrated management of B. tabaci.

Rhopalosiphum padi L. (Hem.: Aphididae) is one of the most important pests damaging cereals specially wheat and lowering the quality and quantity of the production directly and indirectly each year. In this study, the toxicity effect of two extracts of Rubia tinctorum L. (Rubiaceae) and Lawsonia inermis L. (Lythraceae) is compared with two conventional insecticides, imidacloperid and pirimicarb. The study was conducted in petri dish of 8 centimeter diameter using a completely randomized design with five different concentrations for each set with four repetitions on 15 adult insects of R. padi L. (Hem.: Aphididae) 25±2 degree Celsius, relative humidity of 70±5 percent and in photoperiodic of 16 hours lightness and 8 hours darkness. All biometric studies were performed on similar and identical leaves of barley with the method of leaf immersion. The number of dead insects was counted after 24 hours. The results indicated that the insecticide imidaclorperide with fatal effects of 50%, 0.0318 and the methanol extract of henna L. inermis L. with fatal effects of 469.532 micro liter per milliliter were the most and least effective, respectively. Comparison of the results revealed that the extracts of the two plants, especially methanol extract of madder (R. tinctorum L.) with insecticide imidaclorperide and pirimicarb, have especial toxic potential to control the above said insect. Accordingly, as the extracts had less potential insecticidal potential, they should be used in conjunction with other methods.

The Colorado potato beetle (CPB) is the most important pest of potato. Adults and larvae feeding on potato leaves cause economically damage to host. Since this pest overwinters as adults in soil, any disturbance in assimilation and storage of the energy resources may weaken the overwintering adults and lessen their resistance to environmental stresses during the winter. In this research, effects of sublethal concentrations of Chlorothalonil 72% SC were studied on lipid, carbohydrate and protein contents in CPB adults under field conditions. The experiments had a complete randomized four-factor factorial design. The four factors were the concentration (0, 2000, 3000 and 4000 μl/l), sex (male and female), time (3, 6 and 12 day) and number of treatment (first and second). The sugar, glycogen and lipid quantities were determined in milligram per gram of fresh weight. Results showed that Chlorothalonil affected significantly the lipids, glycogens, sugars, proteins and caloric content (p<0.01). The most reductions in bioenergetic resources were observed in adults retreated with the concentration of 3000 μl/l 12 days after second Spraying. After taking into account the control, %61.07, %21.58, %57.22 and %54.46 reduction were found in lipid, glycogen, sugar and energy content, respectively. Also in concentration of 3000 μl/l protein increased as much as 39.94%. So the chlorthalonil reduced the outcome of energy in CPB.

Demographic toxicology is a common method for investigation on the sub lethal effects of pesticides on natural enemies. The side effects of plant extracts from root of madder (Rubia tinctorum L.)، seeds of dill (Aniethum graveolens L.) and seeds of Galbanum (Ferula gummosa Boiss.) in comparision with thiamethoxam were evaluated on life table parameters of C. carnea as Agonoscena pistaciae predator، under laboratory conditions at 25± 2، 65± 5% RH and 16:8 (L: D) photoperiod. The first instar larvae were assayed using Potter Spray Tower method.. Results showed significant differences (p≤0. 01) among treatments for gross reproductive rate (GRR)، net reproductive rate (R0 or NRR)، intrinsic rate of increase (rm)، finite rate of increase (λ) and mean generation times (T). The highest to lowest of gross and net reproductive rate were observed in A. graveolens، R. tinctorun، thiamethoxam and F. gummosa parviflora، respectively. The maximum intrinsic rate of increase (rm) and finite rate of increase (λ) were observed in A. graveolens and R. tinctorun and minimum in thiamethoxam. Thus، the immunity was observed in A. graveolens and R. tinctorun respectively while thiamethoxam and F. gummosa showed the highest inhibiting effect on stable population growth parameters. Two extracts، A. graveolens and R. tinctorun were the best choices، because of their immunity on C. carnea as a biological control agent.

The Lady beetle، Hippodamia variegata is one of the natural enemies of Agonoscena pistaciae. Demographic toxicology is a common method for evaluating sublethal effects of insecticides on natural enemies. Regarding to use of hexaflumuron and spirodiclofen in pistachio gardens، present study conducted to evaluate the side effects of the pesticides on demographic parameters of H. variegata under controlled conditions (26 ±10C، 65±5% RH and 16:8h L: D). For this purpose، 120 fresh eggs were treated with field recommended concentration of insecticides and treated into Petri dishes 6 cm with distilled water was used as control، by dipping method. Results has shown that there were significant differences among treatment for gross reproductive rate (GRR)، net reproductive rates (R0)، intrinsic rate of increase (rm)، finite rate of increase (ג)، intrinsic birth rate (b) and doubling time (DT) parameters. The gross reproduction rates were estimated 24. 43±0. 38، 55. 67 ±0. 49 and 48. 11±0. 66 in hexaflumuron، spirodiclofen and control respectively. In addition، rm were estimated 0. 086±0. 0067، 0. 1086±0. 0045 and 0. 1232±0. 007، Moreover، DT values were recorded as 8. 62±0. 51، 6. 54±0. 25 and 5. 88±0. 29 as above mentioned، respectively. According to this experiments، hexaflumuron had higher negative effect on intrinsic rate of H. variegata and it will be suggested that to be considered in integrated pest management.

Demographic toxicology is a common method for an investigation of the sub lethal effects of pesticides on natural enemies. The present study was conducted to evaluate the side effects of the extracts of Calotropis procera (Willd.) R. Br. (Asclepiadaceae), Teucrium polium L. (Labiatae), Fumaria parviflora Lam. (Fumariaceae) and Thymus vulgaris L. (Labiatae) in comparison with three pesticides: Hexaflumuron, Pymetrozin and Spirodiclofen on life table parameters of Chrysoperla carnea (Stephens) under controlled conditions. One hundred and fifty four fresh eggs were treated through dipping method. Results showed significant differences (p≤0.01) among treatments for Gross Reproductive Rate (GRR), net reproductive rate (R0), intrinsic rate of increase (rm), finite rate of increase (λ), intrinsic birth rate (b) and Doubling Time (DT), while it showed no significant difference for intrinsic death rate (d) and mean generation time (T) parameters. The highest to lowest gross reproductive rates were observed in Pymetrozin, Spirodiclofen, T. polium, C. procera, T. vulgaris, hexaflumuron and F. parviflora respectively. The maximum of net reproductive rate, finite rate of increase and intrinsic birth rate were observed in Pymetrozin while a minimum in F. parviflora. Thus, the immunity was observed in pymetrozin, C. procera, T. polium and T. vulgaris respectively while Hexaflumuron and T. vulgaris showed the highest inhibiting effect on stable population growth parameters. Two extracts C. procera and T. polium are the most suitable choices, because of their immunity on C. carnea as a biological control agent.

The entomopathogenic fungus, Beauveria bassiana (Bals.) Vuill., is one of the facultative insect pathogens with a significant host range and host specificity. Conidial survival may be affected by either environmental factors or by bio-pesticides and chemical products used to protect crop plants. In this research, compatibility of the above mentioned fungus was studied with some traditional insecticides namely: imidaclopride, flufenoxuron, amitraz, and as well with neem (Azadirachta indica A. juss (Meliaceae), Stinking assa (Ferula assa-foetida L. (Apiaceae)), Oleander (Nerium oleander (Apocynaceae)) and NeemAzal-T/S. Effect of pesticides and plant extracts on conidial germination and on vegetative growth of the fungus were studied. The formulations of pesticides and plant extracts were tested in three sets of concentrations (mean concentration-MC, half MC and twice the MC). The results indicated that flufenoxuron, neem, NeemAzal-T/S are not compatible with B. bassiana causing either complete or strong inhibition in its development. The compatible formulations with B. bassiana (isolate DEBI008) were on the other hand imidacloprid, oleander and stinking assa. These later formulations could be employed simultaneously with the entomopathogenic fungus in integrated pest management.