Iranian Journal of Plant Protection Science
Year:2018 | Volume:49 | Issue:1 |Papers Count:15

Various Fusarium species are pathogenic groups that cause economic loss (quantitatively and qualitatively) in Allium cepa L., Fusarium species including F. culmorum and F. subglutinans are of great importance in all onion growing areas. Fusarium infection usually starts from the farm and continue throughout the storage and marketing. Fusarium and basal rots of onion are important around the world. In recent years, they had a large spread in the major onion growing areas in West and East Azarbaijan provinces, and now are the most important disease of onions in Iran. Therefore, in order to identify and study this disease in major areas of cultivation, samples were taken from several fields in East Azarbaijan (Ilkhchi, Azarshahr, Ajabshir, Bonab, Malekan, Marand, Maraghe) and West Azarbaijan (Miandoab, Khoy, Salmas) in summer 2012. After isolation and purification, 140 isolates were obtained. Eighty isolates were selected for pathogenicity test on onion bulbs of which 42 were pathogenic. Among the 42 studied isolates, they categorized as extremely (14. 28%), highly (26. 19%), moderately (40. 48%) and weakly (19. 05%) virulent. Based on morphological characteristics and molecular identification using species-specific primers, eight species were confirmed. Out of the 42 isolates studied, F. subglutinans, with a frequency of 2. 38% and 43% disease severity and F. culmorum, with a frequency of 7. 14% and 50% disease severity are reported for the first time on onion in these areas.

During, 2015-2016 a general survey was conducted in Kermanshah province (west of Iran) in order to identify the fungi implicated in the dieback of pine trees. A sum of 169 fungal isolates was obtained from pine trees showing dieback symptoms. The most frequent species associated with pine trees were different species of Aspergilus (41 isolates), different species of Penicilium (25 isolates), Microsphaeropsis olivacea (16 isolates), Trichoderma harzianum (15 isolates), Rhizopus (15 isolates), Paecilomyces variotii (nine isolates), Microsphaeropsis protea (eight isolates), Neoscytalidium dimidiatum (eight isolates), Eupenicillium (eight isolates), Kalmusia variispora (seven isolates), Cladosporium sphaerospermum (six isolates), Pithomyces sp. (six isolates) and Alternaria sp. (five isolates). Pathogenicity tests were carried out to determine the role of these species on detached. In pathogenicity tests under laboratory conditions, just isolates of M. olivacea, M. protea and K. variispora could infect inoculated branches at 25° C. Three isolates from each species were used for pathogenicity tests on two-year-old pine seedlings. A month after inoculation, symptoms developed as canker. Pathogens were re-isolated from all inoculated plants after observation of symptoms, thus completing Koch, s postulates. This is the first report of M. olivacea, M. protea and K. variispora as the causal agents of pine decline in Iran.

Apple scab disease caused by Venturia inaequalis is the most important economic disease worldwide where the apple is grown and causes annual epidemics. It reduces the quality and quantity of the yields in different regions of Iran. In this study, diversity and population genetic structure of V. inaequalis were surveyed on different apple cultivars using 18 microsatellite markers. 51 isolates were obtained from infected leaf and fruit specimens from wild apple, Iranian endemic and commercial apples from Northern provinces of Iran (Mazandaran, Golestan and Guilan). 28 SSR primers were used to investigate the genetic diversity of this pathogen. Among them, 18 primers showed polymorphism between isolates and populations. AMOVA analyses revealed that 97% of the variation was distributed among individuals within populations, and 3% was attributable to the differences among populations. Gene diversity indexes including Nei’ s gene diversity, Shannon index and allele numbers in every population showed that diversity within the population on endemic cultivars is more than the diversity in the population of wild and commercial cultivars. Also, the population of commercial cultivars has more diversity in comparison with the wild population. High genetic diversity within the populations is caused by annual sexual reproduction, gene flow between populations and probably the existence of this fungus for a long time in this region.

The grape leafhopper, Arboridia kermanshah Dlabola (Hemiptera, Cicadellidae), is an economically important pest in most vineyards of Isfahan. In this study oviposition preference and nymphal developmental time of the pest were studied on nine cultivars including White Yaghotii, Black Yaghotii, Askari, Rishbaba, Khalili, Rotabi, Red Keshmeshi, Black and White Keshmeshi under field and semi-field conditions in Isfahan University of Technology vineyard in two consecutive years. No-choice oviposition preference test was performed using leaf cages under natural conditions and results showed that the highest number of eggs laid per female was obtained on Rish-baba and the lowest amount was recorded on Black Yaghotii cultivar. Based on the choice oviposition preference test, using pots in the semi-field conditions, the highest and lowest oviposition rate were recorded on White Yaghotii and Black Yaghotii, respectively. In addition, the developmental times of different nymphal instars of the grape leafhopper were determined on several grape cultivars in natural conditions. The maximum duration of the total nymphal period (29. 33± 0. 3 days) was observed on the Black Yaghotii and the lowest (26. 33± 0. 88 days) on the White Yaghotii. Results of the oviposition preference and duration of the nymphal period indicated that White Yaghotii and Black Yaghotii were the most and least suitable hosts for A. Kermanshah, between the tested cultivars. In this study, no significant correlation (r2=0. 18, P>0. 05) was found between oviposition preference of A. kermanshah, respectively, and the leaf hair density of different grape cultivars.

Fusarium head blight (FHB), caused mainly by Fusarium graminearum, is one of the most important diseases of wheat in the North warm and humid zone of Iran. The disease has also been reported from the South warm and dry zone of Iran, and in some cases there has been considerable damage from the disease in this zone. For the purpose of identifying FHB-resistant wheat genotypes, the reactions of 32 genotypes of the Elite Regional Wheat Yield Trial of the South warm and dry zone in 1392 (ERWYT-S-1392) to FHB were determined under field conditions in two locations (Gorgan and Moghan) for two successive growing years (2013-14 and 2014-15). The genotypes were also tested for FHB resistance under greenhouse conditions. Results of combined analysis of variance for several datasets including disease incidence, severity, index and Fusarium-damaged kernels (FDK) from field experiments showed significant differences among the genotypes for all traits. Significant differences were also observed among the genotypes tested under greenhouse conditions. Among the 32 genotypes examined, S-92-6 and S-92-7 were the most resistant genotypes to FHB under field and greenhouse conditions. They seemed to have three types of resistance including type I, type II and type IV. These genotypes may be recommended as candidates to replace the older cultivars in the South wam and dry zone in the term of resistance to FHB. In the second priority, three genotypes of S-92-2, S-92-3 and S-92-4 with an optimal level of resistance to FHB may also be recommended.

Common pistachio psylla, Agonoscena pistaciae, is a key pest of pistachio trees in Iran. Sampling was done from three pistachio orchards including Sefid, Akbari and Kale-Ghochi varieties. Sample units for nymphs and adults were leaf and a yellow sticky trap, respectively. The number of nymphs on leaf and adult the number captured by traps was recorded weekly. The densities of nymphs and adults were significantly affected by pistachio varieties. The spatial distribution pattern of A. pistaciae nymphs was determined by indices of variance to mean ratio and regression methods of Taylor and Iwao. Indices of variance to mean ratio showed that spatial distribution of common pistachio psyllid in 2015 on three pistachio varieties was a random distribution. In 2016 and pooled two years, on Sefid variety random distribution and on Akbari and Kalle-Ghuchi varieties aggregated distributions were indicated. The aggregation indices in Taylor's model and Iwao's patchiness regression on the three pistachio varieties and during two years were both significantly greater than one. The spatial distribution of nymphs at Taylor’ s model on Sefid pistachio and aggregated on other varieties in 2015. In Iwao's patchiness regression, spatial distribution in 2015 and 2016 was random on Sefid variety and aggregate in other cases. However, the data obtained showed that Iwao's patchiness regression gave a better fitness with all data in comparison with Taylor's power law. The results can be used to improve the sampling program and implementation of pest management programs of this important pest.

In an investigation on terrestrial parasitengone mites in Mehriz and Taft regions of Yazd province and East Mazandaran during 2010– 2011 and 2011– 2012, nine and seven species were collected respectively. Atractothrombium sylvaticum (C. L. Koch, 1835) is a new record for the Asian mite fauna from Yazd province, Iran. The other species Charletonia terianae Hakimitabar, Saboori and Seiedy, 2013, Cicaditrombium weni Saboori and Lazarboni, 2008, Erythraeus (Erythraeus) garmsaricus Saboori, Goldarazena & Khajeali, 2004, Erythraeus (Zaracarus) rajabii Saboori, 2000, Allothrombium triticium Zhang, 1995, Willmannella kazerunica Zhang & Saboori, 1997, Nagoricanella bella (Zhang, 1996) and Charletonia krendowskyi (Feider, 1954) are new to fauna of Yazd province. Eatoniana gonabadensis (Ahmadi, Hajiqanbar & Saboori, 2012) is recorded for the second time in the world from East Mazandaran, Iran. Erythraeus (Zaracarus) ueckermanni Saboori, Nowzari & Bagheri-Zenouz, 2004, Eutrombidium sorbasiensis Mayoral & Barranco, 2004, Montenegtrombium milicae Saboori & Peš ić , 2006 are new for Mazandaran fauna. Allothrombium pulvinum Ewing, 1917, Charletonia behshahriensis Hakimitabar & Saboori, 2014 and Ralphaudyna iranensis Zhang & Saboori, 1995 were also collected from East Mazandaran.

Bakanae disease of rice is one of the most important rice diseases all over the worlds. Elongation is one of the conspicuous symptoms of Bakanae disease that is caused by gibberellins-producing isolates of the pathogen. The present investigation was done to reconsider the species of Bakanae, the ratio of pathogen’ s species, virulence, gibberellin production and the relationship between virulence and the rate of gibberellin production in 23 isolates by gathering 50 samples of infected plants from rice fields. In order to identify the disease severity, inoculation of the plant stem was done by injection of spore suspension at the seedling stage in the Gohar variety. Results led us to identify two species of pathogen Fusarium fujikuroi and Fusarium verticillioides, and each one of them had a population of 88. 4 and 11. 6%, respectively. Results of the pathogenicity test showed that inoculation of the seedling causes infection in all the plant. Furthermore, the disease severity caused by the tested isolates were different in all the host plants. Results from tests of gibberellin determination using spectrophotometry and HPLC methods revealed that all the isolates were able to produce the hormone but the amount of it differed among isolates. No significant correlation was observed between the amount of gibberellin and percentage of stem elongation (disease severity). Perhaps, it may be due to early effects of virulence ability of the pathogen in comparison with late effects of gibberellin in the host plant. This leads to a lack of relationship between gibberellin levels and the disease severity of the pathogen.

Citrus leaf-miner, Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae), is one of the pests limiting citrus species in Khuzestan. The damage of six citrus species to this pest was evaluated in Ahvaz region orchards. For this purpose, 10 cm long twigs from each tree of the first instar of larvae were randomly selected and covered with a sleeve trap. Then, the date of infection, number of eggs, larvae, pupae, adults, and the duration of larval and pupal stages were recorded daily. There was a significant difference between the studied traits in this experiment. The highest average length of the larval period was related to orange (11. 75± 0. 47 days) and the lowest average of tangerine (6. 50± 0. 28 days) was recorded. Also, the highest mean pupal period was related to key lime (12. 66± 0. 88 days) and grapefruit (11. 66± 0. 67 days), and orange (5. 00± 0. 07 days) had the lowest average. The highest number of pest different life stages was recorded in orange fruit (eggs: 10. 75, larvae: 10. 25, pupae: 9. 75 and adults: 9. 25) and the lowest number was observed in sweet lemon (eggs: 4. 75, larvae: 4. 00, pupae: 3. 50 and adults: 3. 50). The level of contaminated leaf area showed that the highest average of orange (0. 82± 0. 05) and the lowest average of sweet lemon (0. 35 ± 0. 05) were recorded. According to the parameters studied, orange have suffered maximum and sweet lemon and Grapefruit minimum damage from pest attack.

To determine incidence of nepoviruses in vineyards of zanjan province, 168 symptomatic and non-symptomatic samples were collected during season growing 2014-2015. Total RNA was extracted from the 57 leaves and green shoots of selected samples and then cDNAs were synthesized. Genomic segment of Arabis mosaic virus (ArMV), Grapevine deformation virus (GDeV), Grapevine fan leaf virus (GFLV) and Tomato ring spot virus (ToRSV) was amplified by polymerase chain reaction (PCR) using specific primers. The result revealed that the expected bands were amplified at 15. 7, 15. 7, 10. 5 and 14% of different samples belong to ArMV, GDeV, GFLV and ToRSV, respectively. Following sequencing and multiple alignment of nucleotide sequence of amplified fragments with isolates that retrieved from NCBI. Phylogenetic tree was created by MEGA6 software using Neighbour-Joining method. The result revealed that the Iranian isolates were grouped with reported isolates from different regions around the world based on geographical. This is the first comprehensive study based on molecular methods to determine grapevine nepoviruses in Zanjan province and the first report of GDeV from Zanjna based on our knowledge.

The confused flour beetle is an important stored product pest in the worldwide. At first, the essential oil of the aerial parts of rosemary (Rosmarinus officinalis) was microencapsulated and then its physicochemical properties and fumigant toxicity were investigated on Tribolium confusum, in this study. Insecticidal bioassays were conducted at 27± 3° C temperature and 70± 5% relative humidity in the dark. Insecticidal effect of the non-formulated and microcapsules of rosemary essential oil was investigated at 115. 84, 142. 24, 163. 28, 187. 52 and 203. 44 μ l/L air after 24 and 72 h exposure time. Our results demonstrated that the fumigant toxicity of microencapsulated essential oil was significantly lower than the non-formulated essential oil. The mortality rate of non-formulated essential oil at the concentration of 203. 44 μ l/L air reached 76. 6 % after 24 h exposure time and increased to 86. 6 % after 72 h exposure time. While the mortality rate of microencapsulated essential oil at the same concentration reached 44. 9% and 48. 3% after 24 and 72 h exposure time, respectively. Our results revealed that the microencapsulation procedure could be a suitable strategy to obtain a controlled release formulation of R. officinalis essential oil as a botanical insecticide.

Microcerotermes diversus is an important pest of wooden and cellulosic products in diverse landscapes across Iran, including Khuzestan province. Borate toxicants (including borax) as environmentally sound pesticides affect insects by disrupting their physiology and metabolism. In this study, we measured activities of antioxidant enzymes and lipid peroxidation as biomarkers to determine the level of added oxidative stress in M. diversus caused by exposure to borax different concentrations. Then we measured the effects of four concentrations of borax, 1. 5, 2, 3 and 4%, on oxidative stress biomarkers such as malondialdehyde (MDA) as a product of lipid peroxidation, and activity of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), ascorbat peroxidase (APX) and peroxidase (POX) on worker caste of termites. Each of trials was carried out in four replicates. Results showed that with increasing of borax concentration, the concentration of MDA significantly increased and GR and APX significantly decreased. The highest and lowest SOD activity compared with the control treatment occurred with the 2% and 3% borax treatments, respectively. The highest and lowest amount of CAT activity occurred in the 3% and 4%, and POX activity 4% and 3% borax treatments, respectively. Results showed that of the treatments termites’ with different concentrations of borax affected the stress biomarker including malondialdehyde, POX, CAT, GR, APX and SOD antioxidant enzyme levels. Therefore, antioxidant enzymes and MDA can be used as biomarkers to determine the effects of insecticides in the termite body.

English grain aphid, Sitobion avenae (Fabricius), is an important pest of cereal, particularly wheat. The biological parameters of aphid were determined in a growth chamber at 25± 2° C, 60± 5% R. H. and 14: 10 (L: D) conditions in a completely randomized design as a split plot experiment. The main factor was wheat cultivars of Sysonz and Shiroodi, and the subplot consisted of five different pre-infestation periods (0, 2, 4, 6 and 8 days). The results indicated significant differences among the treatments in the aspect of net reproductive rate (R0), intrinsic rate of increase (rm), finite rate of increase (λ ), doubling time (DT) and mean generation time (T) of S. avenae. The highest and lowest rm in Saysonz cultivar was observed on control (0. 092 d-1) and 6 days pre-infestation period treatment (0. 063 d-1), respectively. Also, the highest and lowest rm in Shiroodi cultivar was obtained on control (0. 216 d-1) and 6 days pre-infestation period (0. 157 d-1), respectively. Therefore, it was concluded that the prior infestation of the wheat plants by this aphid for a 6 days period, can reduce population growth rate of the aphid and so it can be used in the IPM of the aphid.

Cucumber downy mildew caused by Pseudoperonospora cubensis is one of the most important diseases of cucumber in Iran. In this investigation the role of β-Aminobutyric acid (BABA) in reducing this disease was studied via spraying of leaves and soil drench. The plants were treated with BABA and after 24 hours leaves were detached and inoculated with the pathogen and kept in a plastic box with favorable conditions for the disease agent. The disease was evaluated six days after inoculation with pathogen by scoring the leaves between 0-9 and the disease index calculated. Result showed that spraying the leaves by BABA had no effect on the disease reduction but soil application of this compound statistically reduced the disease (p≤ 0. 05). The second phase of the experiment was done for evaluating the effect of BABA on the activity of enzymes such as β-1, 4-Glucanase, phenylalanine ammonia-lyase, peroxidase and polyphenol oxidase. Enzymes activity was assayed at 0, 24, 48, 72 and 96 hours after inoculation with the pathogen. Results showed an increas jn enzyme activity at 48-hours post-inoculation with the pathogen and then β-1, 4-Glucanase, PAL, and POX enzymes activities decreased slowly, while PPO enzymes activity decreased rapidly.

Protoplast fusion as a transgenic system is an effective technique improving microorganism performances by making genetic changes. Today, exploitation of this technique has been beneficial in biocontrol of weeds. For filamentous fungi such as Fusarium species, protoplast preparation is the first step in the common genetic transformation process. For this objective, the Fusarium oxysporum isolates were isolated from Bromrape (Orobanche sp. ) and were identified by morphological and molecular characteristics. Thereafter, the effects of various factors including medium and incubation time in spore preparation were evaluated. Furthermore, the effect of some factors on protoplast preparation and longevity including enzyme concentrations, type and concentration of osmotic stabilizers and lytic incubation times were also assessed. The results of this study demonstrated that Spezieller Nä hrstoffarmer Agar was the best medium to prepare spores and the best incubation time for spore germination was 16 hours. In addition, concentrations of 15mM for Glucanex and 20mM for Driselase and 5 hours incubation time were the best lytic enzyme complex and incubation time period, respectively. The KCl at the concentration of 0. 6M was the best osmotic stabilizer in protoplast preparation and longevity.