جستجوی مقالات مرتبط با کلیدواژه « مرگ و میر » در نشریات گروه « گیاهپزشکی »

Legumes are the second most significant plant source of human protein-rich diets after cereals. Additionally, these plants improve soil structure through biological nitrogen fixation. Plant pathogens are one of the most important global constraints on chickpea production. Plant-parasitic nematodes are key damaging agents to crop production. Broad beans, soybeans, lentils, beans, mung beans, and chickpeas are hosts for P. ritteri, and under greenhouse conditions, this nematode reduces the majority of plant growth indices. Various methods are employed to control plant-parasitic nematodes, most of which rely on chemical control. This study was conducted under laboratory and greenhouse conditions to examine the effects of refined wood vinegar, unrefined wood vinegar, chloro carboxylic acid, and sodium dioctyl sulfosuccinate on P. ritteri.

In this study, 66 soil and plant root samples were collected from chickpea fields in Lorestan province's counties. P. ritteri nematodes were identified after extraction using conventional techniques. The number of P. ritteri nematodes per kilogram of soil in an infected field soil was determined, and this soil was subsequently used in laboratory and greenhouse experiments. The effect of four compounds, including refined wood vinegar, unrefined wood vinegar, chloro carboxylic acid, and sodium dioctyl sulfosuccinate, on P. ritteri was investigated under laboratory and greenhouse conditions, as was the mortality of P. ritteri in chickpea. The data were analyzed using SPSS22 software, and tests were conducted using randomized complete block designs.

A comparison of the mean mortality of P. ritteri under laboratory conditions revealed that the highest mortality was associated with a 1% chloro carboxylic acid treatment for 24 h (100%), and the lowest mortality was attributed to a 0.5% refined wood vinegar treatment for 12 hours (25%). Under greenhouse conditions, the chloro carboxylic acid treatment resulted in the highest mortality, 1% (94%), while the unrefined wood vinegar treatment had the lowest mortality, 0.5% (49%). In addition, the mortality rate demonstrated a significant difference at P≤0.05 in two frames of 12 and 24 h for most compounds (except for sodium dioctyl sulfosuccinate 0.5%) and at P≤0.01 in two levels of 1% and 0. 5% for all compounds.

All investigated compounds induced nematode mortality, with chloro carboxylic acid proving to be the most effective for nematode mortality and unrefined wood vinegar the least effective. Consequently, these compounds can be used as pre-planting to control these nematodes.

Unrestricted use of chemical insecticides, especially at high concentrations, has reduced their efficacy. Plant-based pesticides, due to their relatively high safety levels to humans and environment as well as effective control on insects, have become a suitable alternative to conventional pesticides. The aim of this study was to investigate the biological and physiological effects of the formulated essential oil of Trachyspermum ammi (L.) on the larvae of Helicoverpa armigera Hüb. The obtained essential oil was formulated into an emulsion using Tween 20 as emulsifier. Chemical analysis of the extracted essential oil indicated that Terpinen (14.4%), Cymene (18.5%), and Thymol (61.6%) were the major compounds. The essential oil of T. ammi have a significant repellency rate on third and sixth instar larvae of cotton bollworm at different observed time intervals, with an average repellency rate of 61-76%. Regarding fumigant toxicity, the highest concentration of the essential oil (500 µL/L) resulted in 100% larval mortality. The LC50 value for fumigant toxicity measured as 82.73 µL/L. The duration of larval development significantly increased in treatments compared to control. In EO concentrations of 2.5-1.25 percent an increase was observed respectively in the duration of the larval stage by 9 and 7 days. The pupae and adult’s emergence affected in dose dependent manner. At concentration of 50 µl/l, 89% inhibition of protease enzyme recorded. With regards to the biological and physiological effects observed in the formulated T. ammi essential oil, with complimentary researches, it could be used in integrated management programs of cotton bollworm.

The Black bean aphid (BBA), Aphis fabae Scopoli (Hemiptera: Aphididae), is an important pest of agricultural and ornamental plants. Entomopathogenic fungi are important factors in the microbiological control of pests that are considered a good alternative for chemical insecticides. Isolation of novel potential IPF and evaluation of their efficacy against pests are primary steps for achieving a successful microbiological control program. In this study, the efficacies of three Iranian isolates of Akanthomyces lecanii (PAL6, PAL7, and PAL8) and an Iranian isolate of A. muscarius (GAM5) which had been isolated from two hemipteran pests, Pulvinaria aurantii Cock. and Aphis gossypii Glover, respectively, in citrus orchards of west Mazandaran (North of Iran), were evaluated against BBA.

Mortalities of the BBA nymphs and adults caused by different conidial concentrations (104, 105, 106, 107 108 conidia/ mL) of each fungal isolate during other days after treatment (DAT), 1–7 DAT, were determined under laboratory conditions.

All isolates were pathogenic to the aphid causing about 25% mortality. The efficiency of the isolates was not significantly different among the aphid life stages. When the isolate concentrations (up to 55%) and DAT (up to 53.13 times) increased, their effects increased significantly. The highest and lowest mortality rates were observed at concentrations 108 (12.83%) and 104 (5.86%) conidia/ mL, respectively. The highest effectiveness was recorded in seven DAT for all isolates, 15.14% mortality. At one DAT, the isolates caused about 1% mortality in the aphid population with the lowest effectiveness. The highest mortalities were observed for GAM and PAL7 isolates at six DAT, i.e., 16.83 and 16.67%, respectively. Furthermore, the lowest effectiveness was recorded for the isolates GAM and PAL7, at one DAT (<0.1% mortality), respectively.

The isolates had some potentials for microbiological control of the BBA. Time and conidial concentrations, are the critical factors determining the efficacies of the entomopathogenic fungi. The highest effectiveness can be achieved before six DATs. When the conidial concentrations increased, the obtained mortality by the isolates was enhanced. Due to the relatively low efficacies of the EPF and a lag time for getting sufficient mortality, integrated applications of the entomopathogenic fungi with other compatible control agents with faster effects such as biorational insecticides are recommended. However, the laboratory results should be supported with field or semi-field studies before recommending applications of the entomopathogenic fungi against the BBA aphids in greenhouse or field crops.

Sugarcane (interspecific hybrids of Saccharum) is a strategically important cash crop that has an economic and social impact in many countries. Sugarcane mite, Oligonychus sacchari is one of the most detrimental arthropod pests associated with sugarcane during summer. Control of this pest is mainly based on chemical pesticides and cultural practices as well as the application of silicon as a nutritional component of an integrated crop management. In this study, effects of silicon were evaluated on O. sacchari. Experiments were carried out during 2014–2015 and 2015– 2016 at Salman Farsi Agro Industry Farms, Ahwaz-Iran. The two varieties (CP57-614 and CP48-103) were treated by silicic acid fertilizer as foliar application. Five treatments including one spray (0.5 lit/ha), two sprays (0.5 and 1 lit/ha 3 weeks after spray 1), three sprays (0.5, 1 and 1 lit/ha 4 weeks after spray 2), four sprays (0.5, 1, 1 and 1 lit/ha 4 weeks after spray 3) and Control were applied. In each plot, 15 leaves were randomly selected from bottom, mid and top of plant and number of living mites and dry leaves were recorded. Samples were collected 7, 14, 21 and 28 days after the forth application of silicic acid. The results showed that all treatments had significant effects in mite population and leaf dryness versus Control. Among different treatments of silicic acid, four spray application of silicic acid was more efficient than other treatments on mite damage and leaf dryness. It seems that the silicic acid would be a promising product for management of mite damage and could be incorporated with other management strategies in sugarcane IPM.

In the present study, sublethal effects (LC10=21, LC20=52 and LC30=100 ppm) of Bifenazate (Floramite® 24% SC) on biological parameters of the most important phytophagous mite, Tetranychus urticae Koch, was evaluated under laboratory conditions. Data analysis was performed using Age-stage two sex life table theory. Our results revealed that immature development of treated deutonymphs of T. urticae was not significantly affected by sublethal treatments. Female longevity was affected by sublethal concentrations and the highest value for this period was recorded at control (23.36 day). Furthermore, total fecundity was also negatively affected in female mites developed from treated deutonymphs and the lowest value was obtained at LC30 (27.02 egg). We also present data supporting that the sublethal effects could carry over to the next generation. Accordingly, sublethal concentrations reduced the net reproductive rate (R0), and there were significant differences among the values of this parameter at all treatments tested when compared with control (control=57.93, LC10=49.17, LC20=41.50 and LC30=32.87 offspring/individual). The intrinsic (r) and finite (λ) rates of increase were also significantly lower in mites treated with sublethal concentrations. The highest estimated values for r and λ were recorded at control (0.208 and 1.232 day-1,respectively). Finally, with the reduce rate of development observed for individuals treated with sublethal concentrations, the mean generation time (T) was significantly higher in individuals exposed to any concentration tested (control=19.48, LC10=19.80, LC20=20.10and LC30=19.45 day). Our data underline the importance of considering the role of sublethal effects when attempting to evaluate the total impacts of specific pesticide on an insect pest population and its progeny.

The inclination of rice growers towards double cropping system has raised new concerns about changes in pest biological parameters and the excessive release of pesticides in the environment. In this study, some biological traits of the overwintering larvae of Chilo suppressalis (Walker) was compared between single and double cropping rice fields in the northern Iran during 2016 and 2017. Under the same geographical locality, a significantly higher density of the overwintering larvae was observed in double cropping fields during November-March of both years, while larval mortality was lower in double cropping fields. The larvae collected from double cropping fields had significantly wider head capsules and tended to be heavier than those from single cropping ones. Additionally, both male and female pupae collected from double cropping fields had significantly higher body mass than those from single cropping fields. A significant increase in the number of days required for pupation of the overwintering larvae was observed under double cropping system. However, the adult moths emerged from these pupae were significantly higher fecund than those reared from single cropping fields. Results of this study highlight significant changes in some biological traits of C. suppressalis under double cropping system. At least, some of these changes are expected to affect the level of crop damage in the next growing season and thereby, demand higher rates of pesticides for satisfactory management of the pest. Therefore, further studies are needed to explore the pest status and management of C. suppressalis under double cropping system.

In this study, the population density and survival of overwintering larvae of Chilo suppressalis (Walker) (Lep: Crambidae) was compared between single- and double cropped rice fields in north of Iran (Amol) during winter months (November-March) of 2016-2017. According to the results, a significantly higher frequency of overwintering larvae was observed in double cropped fields in both growing seasons and during all overwintering months. Additionally, larval mortality in double cropped fields was significantly lower than those in single cropped fields. The efficiency of three pesticides, diazinon (with two formulations G 10% and EC 60%), hexaflumuron (EC 10%) and fipronil (G 0.2%) as well as an integrated pest management approach (IPM) using mechanical, physical, and biological methods for control of Ch. suppressalis in double cropping fields of Amol was investigated during growing seasons of 2016 and 2017. According to fields experiments, a single application of hexaflumuron or diazinon EC at a concentration of 1.5 L/ha against the first instar larvae resulted in the most decrease in dead heart and white head damage and the highest crop yield in both growing seasons. The effect of IPM approaches on damage and crop yield was also considerable among treatments. Results of this study indicate that hexaflumuron, as an insect growth regulator (IGR) can be efficiently integrated in management programs of Ch. suppressalis. Besides environmental advantages, the integration of insecticides with novel modes of action in rotation with convenient pesticides can decrease the rate of resistance development by the pest in double cropping systems.

Nesidiocoris tenuis Reuter (Hemiptera: Miridae) is a zoophytophagous mirid known as a potential biological control agent of whiteflies and Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae). This predator is widely used in integrated pest management programs in greenhouses. In this study, side effects of four pesticides including pymetrozin, abamectin chlorantraniliprole, mancozeb and iprodion carbendazim on survival and number of offspring N. tenuis were evaluated. Adults of predators exposed to the pesticides through residual and oral routes simultaneously. None of the pesticides except abamectin chlorantraniliprole cause significant mortality on predator but all of them were affected the number of offspring. The highest reduction in fertility was related to abamectin chlorantraniliprole (92.5%). Iprodion carbendazim (43.22%), pymetrozin (37.44%) and mancozeb (17.14%) were next in rank, respectively. Toxicity of pesticides was calculated based on the reduction coefficient, Ex. According to IOBC classification abamectin chlorantraniliprole was moderately harmful, pymetrozin and iprodion carbendazim were slightly harmful and mancozeb was harmless.

The cowpea seed beetle (Callosobruchus maculatus F.) is one of the most injurious insects infesting a wide range of leguminous stored seeds such as Lens culinaris, Vigna radiata, Vicia faba and Vigna unguiculata (1). This insect also causes secondary infestation during pulse storage, and may cause total loss within three months. The bruchids can cause heavy losses in terms of both quantity and quality (4). Heavy infestations of bruchids can cause heating of commodity, which results in quality loss, and mould growth. Currently, the control strategies of stored product insect pests have exclusively relied upon application of fumigants and protectant synthetic insecticides. Chemical control of pests has led to insecticide residues in stored products and insecticide-resistant insect populations (3, 6). Therefore, there is a need for the ecologically benign methods to control cowpea weevil on chickpea. High temperature application has been used to satisfactorily disinfest stored commodities by various technologies. Microwave radiation is one of the most promising biorational pest management tools for farm stored grain and grain processing industries (29). Microwave is a type of electromagnetic energy that provides rapid heating. It appears that high temperatures in a short time period may be lethal to many stored product pests. The present study aimed to assess the lethal effects of microwave radiation on adults of cowpea seed beetle in stored pulses.
The population of C. maculatus was originally collected from Laboratory of Entomology at Ferdowsi University of Mashhad, Iran. The cowpea weevils were reared on chickpea, in a growth chamber at temperature of 28 ± 2 ºC, relative humidity of 60 ± 5 % in the dark. Male and female beetles were treated separately with 2450 MHz at power levels of 90-900 W over a range of irradiation periods from 20 to 960 seconds. Corrected mortality data were subjected to two-way factorial analysis of covariance (ANCOVA) in which the microwave power and insects’ sex were regarded as independent categorial factors and irradiation period as covariate using SPSS Version 16 software. Prior to the ANCOVA test, Levene's test for equality of variances was performed to examine the assumptions for ANCOVA. Moreover, at each radiation power, the values of median lethal time (LT50), i.e., microwave irradiation period needed for the death of 50% insect population, and 90% lethal time (LT90) with 95% confidence limits were estimated separately for male and female beetles by subjecting mortality data to the maximum likelihood program of probit regression analysis using POLO-PC software. This program has a provision for control mortality.
The results indicated that the mortality rates of both male and female adults increased as the exposure period and/or the power of radiation increased. When microwave power levels increased, the time elapsed to achieve maximum lethal effect decreased; this was implied by the results showing maximum mortality achievement in 960 and 80 seconds at 90 W and 900 W, respectively. Male beetles were more susceptible than females, but this difference was not significant based on the LT50 ratio. The LT50 values for the power levels between 90-900 W varied between 674.8 - 41.40 seconds for males and 741.5 - 47.2 seconds for females. The probit analysis showed that the slope values of mortality - exposure time regression lines were in the range of 3.23 - 5.51. According to the likelihood ratio test of parallelism, the slopes of probit mortality regressions differed significantly among various microwave power levels. However, further likelihood ratio test between the paired combinations concerned revealed that the slopes of probit mortality lines differed significantly only between those of 90 and 900W levels. The present results are in agreement with those of Singh et al. (2012) who worked on Callosobruchus chinensis (26). Also, Sadeghi Nasab et al (2004) working on the effect of microwave radiation on three stored product pests, found similar results (25).
The results from our study showed that microwave radiation has a potential to kill insects in stored beans. It was observed that at certain constant power levels, the mortality of beetles increased as the microwave exposure time elongated and vice-versa. Although this strategy can control insect population in stored beans in a short time whilst deserting no chemical residue on food products, the adverse effects of microwave radiation on nutritional quality of food products and seed germination should be investigated. Further research is also recommended to improve methodology for practical disinfection of stored pulses.

The effect of different concentrations of Metarhizium anisopliae strain EUT115 along with control was investigated on various life stages of green peach aphid Myzus persicae, and different canola cultivars, Brassica napus. Thirty aphids of each stage were treated with the fungus and then transferred onto Petri dishes containing leaf-discs placed on 2% water-agar medium. The aphid mortality was recorded daily for 14 days after the beginning of the test. According to the results, after 7 days, the highest mortality was obtained on the RGS003 (5.47 ± 0.44) and the lowest mortality was occurred on the Zarfam genotype (4.983 ± 0.45) and the significant difference was observed between the two genotypes. The highest mortality among the different life stages happened for the adults and was calculated 7.64 ± 0.65 and 8.82 ± 0.50 aphids after 7 and 14 days, respectively. Among the various fungal concentrations, 107 conidia/ml of the fungus caused the highest mortality after 7 (8.38 ± 0.24 aphids) and 14 days (9.60 ± 0.12 aphids), respectively. The results showed that there was interaction between the fungal concentration and the aphid life stage. It is suggested that to control enormous infestation of the green peach aphid in canola fields, the RGS003 genotype and 107 conidia/ml of the fungus can be used. The mean mortality of the aphid was increased by increasing the time from spraying the pathogenic fungus. It shows the importance of fungus-sporulating cadavers of the aphid as a reservoir in surrounding environment.

In this study formulations were prepared by emulsion of different vegetable oils (sunflower corn rosemary olive sesame and walnut) of Metarhizium anisopliae (Metschnikoff) Sorokin conidia. Control formulation was also prepared and germination of fungal conidia in all formulations was assessed. Results showed that control and olive oil formulations had the highest average conidial germination while the sesame oil formulation had the lowest germination. Effect of four concentrations (108 107 106 and 105 conidia/ml) of these formulations were applied against populations of Microcerotermes diversus Silvestri (Isoptera: Termitidae) termites. Due to high mortality rate in the first three concentrations the treatment with 105 conidia/ml was used in comparisons. The highest mean percent termite mortality (91.25%) was obtained with the sesame oil formulation and the lowest (58.33%) with control formulation. The lowest LT50 (2.38 days) occurred with the sesame oil formulation while the control formulation had the greatest LT50 (15.9 days). The lowest calculated LC50 (1.7  104 conidia/ml) was also for sesame oil formulation.

Melon aphids, Aphis gossypii Glover (Hemiptera: Aphididae) is one of the most important pests causing damages in vegetables fields and greenhouses. In this regard, pesticide application is usually considered as the most common forms of pest control. Excessive use of chemical pesticides, leads to an increase in pesticide residue in vegetables, and affects on consumer health. In this study, the sensitivity of the different nymphal instars and adult melon aphids to field recommended dose and half-dose of the insecticides imidacloprid (35% SC) and primicarb (50% WP) was surveyed by leaf dipping. The bioassay was also carried on the third instar of melon aphid. Moreover, based on LC50, the sensitivity of third instar was compared at intervals of 24, 48 and 72 hours, in both insecticides. The results showed that the toxicity of both pesticides was significantly reduced in later stages. Based on the results obtained, LC50 and LC90 of imidacloprid were 71.648 and 365.548 and for primicarb were 212.62 and 457.49 ppm, respectively. The mortality for imidacloprid was 45, 48.89 and 49.45% and for primicarb 43.89, 47.78 and 50.56%, after 24, 48 and 72 hours, respectively. The results also revealed that in both insecticides, the highest mortality were occurred after 24 hours and the passage of time (48 and 72 hours) did not result in higher mortality. According to results, the pest is well controlled by low doses of both insecticides, the issue that can also reduce harmful side effects on consumer health and the environment.

The use of wood preservatives is a suitable method to protect wooden products from termites attack. The effect of a Glycol Borate wood preservative and termiticide (available commercially as Bora-care) alone and in combination with Furfural were evaluated against M. diversus Silvestri (Isoptera: Termitidae). The major termite pest in Khouzestan province، Iran in choice and no-choice tests. It was found that mortality and repellency increased with increasing concentration of glycol borate and also with increasing Furfural concentrations. LC50 values in choice and no-choice trials increased for Furfural as time increased and their toxicities decreased proportionally، but LC50 values decreased for the Bora-care as time increased and their toxicities increased proportionally. LT50 values in choice and no-choice trials had an increasing trend as concentration decreased. In all tests، the glycol borate with Furfural prevented feeding and treated cellulose substrate damage. The results suggest that Bora-care alone and in combination with Furfural could be recommendable as wood preservatives against M. diversus.

The common pistachio psyllid, Agonoscena pistaciae, is known as a key pistachio pest in Iran. The two spotted coccinellid, Adalia bipunctata was reported as a psyllophagous beetle and the most abundant predator in pistachio plantations of Rafsanjan, south of Iran. The present research was carried out to examine the influence of temperature on biological parameters of A. bipunctata using psyllid nymphs as diet and under controlled conditions e.g., constant temperatures (ranged from 17.5 to 35°C), 55±5% r.h. and 16L:18D. The reproduction, developmental thresholds, thermal constant and the intrinsic rate of natural increase of this ladybird were all tested. The lower threshold for A. bipunctata while fed on nymphs of A. pistaciae was estimated 13.1. Thermal constant for development of this ladybird from egg to adult was obtained 200°DD (Degree-Day) while reared on nymphs of A. pistaciae. The intrinsic rate of natural increase (rm) and finite capacity for increase were obtained 0.172 and 1.19 respectively. Based on present results, A. pistaciae is considered as a suitable diet for this ladybird.

The Asian citrus psyllid, Diaphorina citri Kuwayama, is a vector of Candidatus Liberibacter asiaticus that causes citrus greening disease. The vector population has increased drastically in our country, in recent years. Entomopathogenic fungi are among those agents which might have the potential to suppress its population. To study the effects of these agents on adult psyllids and the relationship between fungus-sprayed area and mortality, two isolates, DEMI 002 (Metarrhizium anisopliae) and DEPI 002 (Isaria tenuipes) were investigated in the laboratory. Four leaf sections were placed together in a Petri dish and one to four of them were sprayed by the fungal suspensions at a concentration of 7×105 spores/ml and two adult psyllids were released into Petri dishes. Five days after treatment, ‘DEMI 002’ and ‘DEPI 002’ caused 71% and 29% mortality, respectively. DEMI 002, an isolate of Metarrhizium anisopliae, was significantly more effective than DEPI 002(Isaria tenuipes). However, there was no statistical difference between different leaf area coverage on mortality, showing the horizontal transfer of the fungi among the psyllids. Application of entomopathogenic fungi at low quantities combined with other control techniques is an appropriate option in an IPM approach against D. citri.