مجله دانش گیاه پزشکی ایران
سال چهل و هفتم شماره 2 (پاییز و زمستان 1395)

The Colorado potato beetle, Leptinotarsa decemlineata (Say) (Col.: Chrysomelidae) is the most important phytophagous pest of potato in Iran. In this research, diversity and abundance of terrestrial predators, and density of Colorado potato beetle eggs, larvae and adults were studied in potato rows located at 5, 10, 15, and 20 m from the alfalfa field (in the potato field adjacent to the alfalfa field) along with the control (the sole potato field) in Ardabil region during 2014 and 2015. In this study, eight terrestrial predator species in the control potato field and fourteen terrestrial predator species in the potato field adjacent to the alfalfa field were collected using pitfall trap and identified, amongst which spiders and carabid beetles had more relative abundance. The Shannon diversity index (H’) for terrestrial predators in the potato rows located at 5, 10, 15, and 20 m from the alfalfa field (in the potato field adjacent to the alfalfa field) was significantly higher than in the control potato field. During two years, the abundance of spiders and Carabid beetles decreased with increasing distance of the potato rows from the alfalfa field. Moreover, the density of Colorado potato beetle eggs, larvae and adults increased with increasing distance of the potato rows from the alfalfa field. Therefore, use of the strip cropping of potato and alfalfa (with 10 m of the potato strips width) could be recommended to the farmers in the integrated management of Colorado potato beetle.

Tomato (Lycopersicum esculentum Mill.) is one of the most important crops in Iran and throughout the world. In the previous survey conducted in 2013, PVY was introduced as the dominant virus in Yazd (Iran). In the present study, the partial genome sequence of a selected isolate called T5 was determined and analyzed. Following total RNA extraction of the T5 isolates, three fragments with 824, 1700 and 837 bp lengths were amplified using CPr/CPf, M4T/Sprimer and P1/P2 primer pairs respectively in RT-PCR. According to the nucleotide and amino acid sequences comparison of the CP, NIb and P1 regions of the isolate with the other PVY isolates in the Genebank, T5 is a member of NTN strain.

In order to monitor canola stem borer weevils, Ceutorhynchus spp., determining the appropriate time for control, and investigate the efficacy of insecticides, this research was conducted in a RCBD with five treatments and four replicates in Sari during 2011-2012. Yellow water traps were used for monitoring the pest. The treatments were a) chlorpyrifos EC40.8% (2 l/ha), b) imidacloprid SC35% (1 l/ha), c) diazinon EC60% (1.5 l/ha), d) fenitrothion EC50% (1 l/ha) and e) control. Four plants per plot were collected 1 day before and 5, 14, and 21 days after treatment and the pest larvae were counted. One week prior to harvesting, the numbers of healthy pods (HP) and blind stalks (BS) on three plants per plot were counted. 1 m2 of the crop per plot was harvested, and the yield and thousand kernel weight (TKW) were measured. First and last weevils were caught in early November and late December, respectively and its peak occurred in late November. Oviposition began in late November and its peak occurred in early December. The efficacies of the treatments a, b, c and d at 14 days after treatment were 88.89±6.51, 57.57±9.61, 83.20±6.00, and 91.82±6.13 percentage, respectively. Compared to ghe control, TKW and yield increase in a, b, c, d were 0.8, 0.4, 0.48, and 0.43 g; 115.5, 68.2, 79.5, and 62.8 g, respectively. HP and BS in a, b, c, d and e were 77.17±11.63, 43.58±1.93, 44±9.10, 44.75±7.06 and 31.75±3.35; 4.50±0.29, 8.75±0.98, 13.25±1.42, 18.33±3.54 and 14.83±2.76, respectively. Chlorpyrifos with appropriate efficacy, had the highest yield, TKW, HP and the smallest BS.

Two spotted Spider mite is the most important polyphagous pest which causes considerable damage to different crops including eggplant annually. Nowadays, using different integrated control methods against the spider mites is one of the most appropriate ways to reduce pesticides use and increase agriculture safety which can be achieved through selecting resistant varieties. In this study, the antixenosis and tolerance mechanisms of 11 genotypes of eggplant were investigated in a greenhouse with temperature fluctuations between day and night ranging from 18 to 27˚C in the form of a completely randomized design with three replicates. Also, protein expression in different genotypes was evaluated using SDS-PAGE and the relationship between protein expression and the number of spider mites attracted to each species was analyzed by the antixenosis test. To determine the correlation between greenhouse traits and molecular data, the Mantel test was used. The hierarchical grouping method of the ward was used to classify genotypes traits which led to four clusters of resistant (Borazjan, Yalda and Linda), moderately resistant (Black beauty, Lady and Mahali-Zabol), moderately susceptible (905 Emami, Kime and Blacky) and susceptible (Siahe-Mashhad and Lima). Results clarified that Borazjan, Linda and Yalda genotypes could be considered as potential T. urticae resistant genotypes and be examined in further experiments.

In order to investigate the effect of different stages of sorting line on the development of orange post-harvest disease, two independent experiments were conducted. In the first experiment, fruit sampling was done upon arrival at the workshop (control) and after imposing each sorting line stage included washing with water immersion, washing with fungicide-containing hot water, waxing, sorting, as well as the elimination washing with hot water containing fungicides from the last two levels of the sorting stage (waxing, sorting). The fruit decay was assessed in three phases (7, 14 and 21 days after keeping the fruits at germinator). In the second experiment, the control fruit and final product of sorting (waxed oranges washed and unwashed with fungicide-containig hot water) were kept for 45 days in cold storage. The results showed that green mold, blue mold, and sour rot are the common diseases in the oranges. No significant difference was observed between the sorting treatments in the two modes of washed and unwashed with fungicide containing hot water. Further, more the percent of disease incidence and mean the disease severity increased over the time. Control treatments had 5.9, 33.3 and 33.3 percent of disease incidence in 7, 14 and 21 days evaluation steps, respectively. In the second experiment, the disease incidence was significantly lower in control compared to the other two treatments. In conclusion, it can be stated that sorting, as it is, increases post-harvest diseases and the rate of fruits decay cannot be reduced by using hot water containing fungicide and wax.

The oak leaf roller moth (Tortrix viridana L.) is one of the most important oak pests in Iran. In order to investigate fluctation changes of this pest, weekly samplings of its different life stages were done in West-Azerbayjan. The number of larval instars were determined by growing and measuring the head capsula width of 1000 larvae at different ages. The effect of host plant on weight changes of final instar larvae and pupae on three oak species of Quercus infectoria, Q. brantii and Q. libani was studied. Populational changes of adult insects were investigated using 10 triangle pheromone traps. Five larval instars were determined for this pest. Neonate larvae of the pest start their activities from late March in Mirabad and from early April in Paradanan. The formed larvae and pupae on gall oak (Q. infectoria) weigh more than there growing on two other oak species. Adult insects were first captured on May 23 in Mirabad (6.2 insects in each trap). The highest degree of pest capture was also recorded at the peak
time of pest population with the average of 132 insects in each trap in Mirabad which indicates that this area is highly infected with the pest. The oak leaf roller moths stopped their activity in mid-July in all of the studied areas.

During September to November 2010-2012, 17 fruiting body specimens of Armillaria were collected from diverse forest sites in Guilan, Mazandaran and Golestan Provinces (Iran) and 24 basidiocarp derived isolates were obtained. Mating tests were performed using 10 Iranian representative isolates and 12 European tester strains of European species including A. mellea, A. gallica and A. cepistipes. Crossing tests were also used for identification of interspecific and intraspecific separation criteria. In the mating test of a total number of 360 interspecific crosses, Iranian isolates were divided into two A. mellea and A. gallica groups. Hemi-compatible and compatible reactions were found in 126 interspecific crosses. Analysis of crosses demonstrated clear separation for both MFF (mycelial fusion frequency) and BLF (black line frequency) and also change in culture morphology. Mating data clearly distinguished three species including A. mellea, A. gallica and A. cepistipes and defined sexual compatibility of Iranian species with their European counterparts. In spite of close phylogenetic relationship between Iranian A. gallica and A. cepistipes, it also represented a significant clear cut based on the sexual fertility. The results suggest that biological species concept in these fungi consist of using both somatic and sexual compatibilities that still can be used in case of selection of a proper pattern of isolates.

Pear psylla is one of the most important pests of the pear trees in the world and Iran and the chemical control is the leading control method against it. Recently pesticide injection has become an effective and special control method against the sucking pests. The aim of this study was to determine the efficacy of complete fertilizer and its mixture with azadirachtin by injection against pear psylla. The experiment was conducted on pear trees var. Shah Miveh in Mehrshahr orchard near Karaj city with 4 treatments and 5 replications in a randomized complete block design (RCBD) in 2014. Treatments included injection of complete fertilizer (Nutreeno®), alone and mixed with azadiractin, foliage application with diazinon EC 60% at the concentration 1.5 ml/L and control (spraying water). The results showed that the densities of psylla eggs and nymphs in the injected treatments were less than spraying. The treatment efficacies of diazinon, Nutreeno alone and mixture with azadirachtin were 28, 91, and 85% in the last season, respectively and the amount of honeydew per leaf in the sprayed treatment was twice more than the injection. Physical aspects of pear fruits, including weight, diameter and length of the fruits in both injected treatments were 10-20% more than the conventional application. According to this study results, trunk injection can reduce the amount of used insecticides per tree and also the usage of organic fertilizers can increase induced resistance of plants against pear psylla.

Following the random sampling of saffron (Crocus sativus L.)leaves and corms from six provinces of Iran, during growing seasons of 2011-2015, a total of 890 leaf tissue samples were investigated by enzyme-linked immunosorbent assay (ELISA) tests. The results revealed that 641 samples showed positive reaction only with Potyvirus genus specific and exactly with Bean common mosaic virus (BCMV) specific antibodies. The molecular mass of several isolates of the virus coat protein (CP) was estimated as 35 kDa by western blotting. Following total RNA extraction from virus infected samples, three discontinuous fragments (corresponding to genomic 3', partial CI and HC-Pro regions) were amplified. The CP region of the virus infecting saffron has the highest nucleotide identity with Ceratobium mosaic virus (CerMV) and Telosma mosaic virus (TelMV) (74%) and the highest deduced amino acid identity with Bean common mosaic necrosis virus (BCMNV) (78.8%). Despite the high serological relationship with BCMV and a close phylogenetic relationship with BCMV subgroup based on CP region, the identity values are less than described species demarcation criteria for Potyviridae family. Overall, it seems that the saffron infecting Potyvirus is a new species of Potyvirus genus but the definitive statement requires sequencing the entire genome of the virus.

In this study effect of systemic resistance inducing fluorescent pseudomonads on wheat bacterial leaf streak was investigated. According to the importance of produced siderophore by this kind of bacteria in the induction of systemic resistance, CAS agar medium was used for screening of the isolates with the highest potential for siderophore production. From the 200 isolates that isolated from North West part of Iran, 37 could produce a large amount of siderophore and the diameter of hallo zones produced by these isolates on CAS medium agar was more than 15 mm. Ethylene production bioassay was used for screening the isolates with the potential for induction of systemic resistance in wheat. Among these isolates, only four increased the plant reaction potential against XTC and concentration of ethylene produced by leaf pieces of plants treated by these isolates was more than 2 pmol/ml air. The effect of selected isolates on bacterial leaf streak of wheat in growth chamber was investigated and it was found that only 58A can significantly decrease this disease. Investigation of the enzymatic changes of plant treated by this isolate during pathogenicity process showed that the presence of this bacterium on the wheat roots doesn’t have any effect on peroxidase (PO) and phenylalanine ammonia lyase (PAL) activity in foliage, but after inoculation of the pathogen, the activity of both of them increased.

Microbial volatiles have an important role in plant growth promotion and protecting them against plant pathogens. In this work, we evaluated whether B. subtilis volatiles promote plant growth and induce resistance against P. syringae pv. tomato DC3000. Arabidopsis seedlings exposed to bacterial volatiles in two compartments I-plate system. Volatiles increased plant growth significantly compared to control. Exposure of plant with bacteria volatiles reduced disease index from 80% to 40%. Pathogenic bacteria population in plant leaves reached up to 1.1×106 CFU/g aerial part wet weight, in volatile treatment, however pathogen population reached up to 1.3×108 in control plants. Expressions of PR-1, PDF1.2, and ChiB have been evaluated as marker genes for salicylic acid, jasmonic acid and ethylene-depended pathways, respectively. Bacteria volatiles boosted the expression of PR-1 and PDF1.2, significantly. These genes expressed strongly and rapidly which represent plant defense priming by bacteria volatiles. In conclusion, volatiles from B. subtilis GB03 not only improved plant growth significantly but also increased expression of defense-related genes and eventually suppressed disease in Arabidopsis.

The functional response is the most basic form of predator-prey interaction and describes the relationship between the number of prey attacked and the initial prey density. Hyperaspis polita Weise (Col. Coccinellidae) is one of the most important predators of some species of mealybugs and is collected from some parts of Iran especially Khuzestan province. In this research, the functional response of the fourth instar larvae, females and males of this predator to varying densities of female cotton mealybug Phenacoccus solenopsis Tinsley was assessed in a growth chamber (30±1˚C, 65±5% R.H. and photoperiod of 14:10 (L:D) h). A cubic logistic regression between the proportion of prey killed and initial prey densities was performed to determine the shape (Type II or Type III) of functional response. Based on the logistic regression, functional response type II were determined for all predator stages. The attack rate (a), handling time (Th), and theoretical maximum predation rate (T/Th) were estimated using Roger's model to be 0.0196±0.0029 h-1, 3.3262±0.4551 h, and 7.2 prey/d for fourth instar larvae, 0.0131±0.00238 h-1, 3.4765±0.7419 h, and 6.9 prey/d for adult females and 0.0195±0.00528 h, 12.013±0.2624 h-1, and 1.99 prey/d for adult males respectively. According to our results, the fourth instar larvae and the adult females of H. polita can be applied as an effective biological control agent against P. solenopsis.

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.

Biological control of soil-borne diseases of plants has received serious attention among plant pathologists in recent years. In this regard, Rhizobacteria, more specifically fluorescent pseudomonads are known as an effective biocontrol of plant diseases. Pseudomonas spp. are promising agents to manage the disease caused by Sclerotinia sclerotiorum and Pythium aphanidermatum. In this study, we screened 81 bacterial isolates from cucumber rhizosphere for their antagonistic effects against the pathogens using dual culture method and investigating their ability to produce inhibiting volatile metabolites. Results indicated that isolates 19C, 21B, 24A, 33B, 33C, 38A, 42D, and 43C had significant inhibitory effects on the pathogens and their volatile metabolites significantly reduced the mycelial growth of the pathogens in comparison with controls. In greenhouse trials, isolates 19C and 24A reduced disease index of Pythium aphanidermatum more than 70% and that of Sclerotinia sclerotiorum more than 60% compared with controls. The isolates 19C, 24A, 33B, and 33C were able to produce protease. Isolate 19C was able to produce surfactin and isolates 33B and 33C were able to produce hydrogen cyanide. Molecular identification of isolates was conducted based on partial sequence of 16srDNA amplified by specific primers fD1 and rD1 thereby the isolates showed significant homology with Pseudomonas spp., Stenotrophomonas spp. and Flavobacterium spp.

Beet curly top Iran virus (BCTIV) is one of the factors causing leaf curl disease in tomato plants. Most tomato cultivars have been grouped as susceptible and some moderate resistant to BCTIV. In addition, the level of minerals varies between susceptible and resistant plants in response to plant pathogens. In this study, the level of key minerals was evaluated using ICP-MS in both susceptible and moderately resistant tomato cultivars in response to infection by BCTIV; based on a completely randomized design. Results showed that among five tested minerals including ion, phosphorus, potassium, calcium and magnesium, the level of potassium was higher in Super Chief, the moderately resistant cultivar, compared to that of Grosse Lisse, as the susceptible cultivar. In addition, the level of potassium accumulation in leaf tissues increased significantly (P