Applied Entomology and Phytopathology
Year:2020 | Volume:88 | Issue:1 (110)|Papers Count:14

Cereal stem sawfly, Cephus pygmaeus (Hym: Cephidae), is an important wheat pest. The pest larvae feed inside wheat stems and cause damage. This project was carried out in a completely randomized block design with 7 treatment and 3 replications (21 plots, 3 m×4 m) in Farim region, Sari, Iran, during 2015-2016. Evaluation of damage caused by the pest on two common wheat cultivars (Morvarid and Gonbad), four promising wheat lines (N91-9, N91-10, N91-14 and N91-17) and one barley cultivar (Sahra) were investigated. On harvesting time, all plants located in 1 m 2 of each plot were sampled including their roots. The numbers of infested stems were counted and percentage of infestation measured. Diameter of 20 intact and 20 infested stems, 100 kernel weights of healthy and infested plants and the grain weight of 1 m 2 of each plot were measured. Data were analyzed by MSTAT-C software and the means were compared using Tukey test. Regarding the percentage of infestation, there was no significant different between the common cultivars and the promising lines of wheat. However, the barley cultivar (Sahra) had significantly less infestation compare to wheat treatments.

Western and north western provinces of Iran have the highest potential for chickpea cultivation in Iran. Vascular wilt caused by Fusarium oxysporum f. sp. ciceris (FOC) is one of the most important diseases of this crop which distributed in chickpea cultivation areas of these provinces. The purpose of this study was to identify the pathogenic races of FOC in the western and north western provinces. Sampling was conducted on three infected locations. After isolation of the fungal isolates, identification was performed using FOC specific primers by PCR method. Out of 116 isolates identified, 94 isolates belonging to three locations were selected to recognize the fungal races. Five races including R0, R1B/C, R1A, R6 and R5 showed the highest abundance in the studied areas, respectively. Presence of five races from the eight identified races of FOC in the world in western and north western provinces of Iran indicates the high genetic diversity of this fungus in the country and distribution of the races of this fungus is independent of environmental factors.

This study was carried out to investigate the effect of salicylic acid (sa) and chitosan (chi) on the response of rice to Fusarium fujikuroi, the causal agent of root and crown rot of rice plant. The effect of chitosan and salicylic acid with the concentrations of 200 and 400 ppm on mycelial growth of the pathogen was measured. Furthermore after 0, 24, 48, 72, 96, 144 and 288 hours of inoculation, growth traits of the plant and enzyme activity of peroxidase and catalase were evaluated in rice seedlings of a susceptible cultivar namely Tarom. Salicylic acid and chitosan in 400 ppm had the most mycelial inhibitory effect with 35. 57 and 24. 29% respectively. Both treatments could significantly reduce disease symptoms; the least disease severity was assessed 37. 8 and 41. 7 % in 200 and 400 ppm concentration of salicylic acid and chitosan respectively. Sa-200 and chi-400 pretreatment could significantly (P<0. 05) increase the shoot and root length and root volume of seedlings compared to control. The maximum level of peroxidase activity was assessed 96 hours after inoculation in 200 and 400 ppm concentration of salicylic acid and chitosan respectively. The minimum level of catalase activity was assessed 48 hours after inoculation in 200 and 400 ppm concentration of salicylic acid and chitosan respectively. Thus salicylic acid and chitosan could effectively induced systemic resistance in rice resulted in the reduction of disease severity.

Verticillium wilt of olive (VWO) caused by fungus Verticillium dahliae, is one of the most important diseases of olive worldwide. The response of 15 promising olive cultivars and 15 local varieties was evaluated to the fungus. The olive saplings of each genotype were inoculated with suspension of the fungus using root dip method. The degree of susceptibility/resistance of each genotype was evaluated based on both morphological feature and quantification of fungus in the root system of different genotypes. Total DNA was extracted from root of saplings at different sampling intervals: 0, 2, 12, 45 and 80 days post inoculation. The gradual increase for DNA of fungus in saplings was quantified by Real-time PCR technique and utilizing of SYBR Green system with specific primer pairs for ß-tubulin2 gene. Based on both morphological and quantitative Real-time PCR assays: QG-11, DD2-1, treeNo2, PS-5 and Manzanilla were highly susceptible and KH-13, TTS-1, DS-5 code 5 Lorestan and DS-5 were evaluated as resistant genotypes to the VWO. Moreover, we found parallel results for conventional method of screening (based on disease symptoms) and quantification of DNA in root system of olive by Real-time PCR technique. Olive genotypes evaluated as highly susceptible or resistant to the disease in conventional method showed the similar reaction to the fungus in Q-PCR method. This may suggest that conventional method of evaluation for resistance could be replaced by Q-PCR molecular method in high thropout screening of olive germplasm.

Sunn pest, Eurygaster integriceps Puton (Hemiptera: Scutelleridae) is the most important pest of wheat and barley in Iran. The aim of this study was to determine the resistance probabel levels of summer populations of Sunn pest collected from Varamin (under the pressure of insecticides) and Gonbad (with no history of insecticide application) regions. Toxicity of the insecticides for the collected adults was measured using a topical bioassay. Treatments were performed under the pronotum with each insecticide in acetone for treatments and acetone alone for the control. The treated insects were maintained in laboratory conditions and mortality was recorded 24 hours after treatment. Fenitrothion LD50 values for Gonbad population males and females were 26. 27 and 26. 8 ug/insect, respectively. Varamin population LD50 values were also estimated 135 and 157. 11 ug/insect for fenitrothion, respectively. LD50 values for deltametrin estimated for males and females of Gonbad population were 0. 025 and 0. 15 ug/insect. The values were also estimatid 0. 47 and 1. 75 ug/insect for males and females of Varamin population, respectively. Based on the overall results, Sunn pest showed reduced susceptibility of Varamin population to both insecticides studied. Although the susceptibility to deltamethrin was higher, its resistance ratio was also higher than fenitrothion concerning the probability of resistance development. The results obtained can be useful in Sunn pest control programs.

Pistachio die-back is one of the most important and prevalent diseases of pistachio orchards, causing severe reduction of pistachio yield. Due to the important role of bacteria in the occurrence and development of pistachio die-back, the interaction of Bacillus spp. and Paecilomyces formosus was investigated in this research. The isolates of both groups were injected beneath of the inner bark of branches (Ohadi cultivar) using sterile syringes alone or in mixture. According to the results, Bacillus pumilus and P. formosus isolates were able to cause disease on the branches, with longitudinal developments in vascular tissue. Bacterial isolates alone caused lesions ranged 4. 5-14 cm in inoculation sites. Mix inoculations, significantly, increased disease development in xylem varied 10-32 cm. Based on morphological, biochemical and molecular properties, isolation of B. pumilus strains is reported for the first time as one of the causal agents of pistachio die-back in Iran.

The partial resistance of pumpkin (Cucurbita maxima), hybrid squash (C. maxima * C. moschata), fig leaf gourd (C. ficifolia), grilled linear pumpkin, Luffa (Luffa aegyptiaca), two cucurbits nuts Khoy (C. pepo) and yellow cucurbit nuts against Fusarium oxysporum f. sp. radicis-cucumerinum (Forc) causal agent of fungal root and stem rot disease of cucumber evaluated and compared with royal cucumber. The results showed that, fig leaf gourd, pumpkin, hybrid pumpkin, two cucurbits nuts Khoy 1 and 2 are resistant, Luffa, yellow nut pumpkin and grilled linear pumpkin were moderately resistant and royal cucumber was sensitive. The mean percentage of disease severity in cucumber royal (control) was 80%. The lowest disease severity was observed in hybrid pumpkin 24. 16%, pumpkin 25% and fig leaf 25. 83%. The results showed that graftted hybrid pumpkin with disease severity of 18. 6% was the lowest and non-grafted cucumber with 82% was the highest. In terms of rootstock effect on dry root weight, pumpkin with 5. 3 g had the maximum and non-grafted cucumber with 0. 73 g show the lowest root weight. non-grafted cucumbers with 1. 73 kg per plant were the least and cucumbers grafted on hybrid pumpkin 5. 7 kg, pumpkin 1. 5 kg and fig leaf gourd 5. 03 kg showed the highest yield per plant. The results showed that grafting of cucumber on the cucurbit rootstocks reduced the percentage of disease severity caused by Forc.

Dubas bug, Ommatissus lybicus, is one of the key pests of date palm groves in Iran. Chemical control is currently used regardless of the population of pests and its economic problems. The aim of this study was to determine O. lybicus economic injury level with a different method from the conventional method which is easier with the same precision. Therefore, Delphi method or expert system was used. It was carried out in the three provinces of Kerman (Bam), Fars (Farashband), and Bushehr (Tang-e zard). Twenty-five questionnaires were distributed between experts and farmers in each province. The completed questionnaires were collected. According to the results of the first questionnaire, the second questionnaire was compiled and the stages were repeated. The results showed that the Delphi method provides valuable results such as the description of individual variables (the age of palm growers, literacy, level of experience, garden area and gardener pest management) that can be effective in pest management planning. However it could not produce accurate results for quantitative data such as determining the timing of chemical control according to pest number, the amount and percentage of damage, because this data is available and the Delphi method should not be used as an excuse, in such cases the Delphi technique can be used as a complementary method.

Due to the high speed and accuracy of intelligent pest detection in warehouse products, in this study, the detection of chickpea fourpoint beetle pest was simulated by image processing technique using artificial neural networks. To prepare the images, a glass box was prepared and the chickpea seeds were placed in the center of the box. The light was then illuminated from all six sides and photographed with a digital camera from all sides. The image properties were then extracted by Wavelet Gabor using MATLAB software and applied to the ANN as training data. To train the network, 69 images of chickpeas damaged and 59 healthy chickpeas were used. Then, to evaluate the network, a set of data that did not play a role in network training as test data was applied to the network and its results were evaluated. In this study, Perceptron and Elman neural networks were used which had better results than Elman network. The proposed method was able to detect the high rate of damaged with 6. 17% non-detection error and 4. 86% error-detection error. After image processing by the neural network and detection of damage points, the amount of crop damage was also calculated. For this purpose, the level of detected damage was calculated and divided by the area of total area of chickpea seed and percentage of damage. After identifying the injury sites, the damage was estimated 2. 3% in the studied images.

Winter sunscald is a physiological disorder that causes damage to almond and peach trees in some orchards of Chaharmahal va Bakhtiary province. In orchards with favorable conditions for this disorder bacterial canker was more severe observed. Early symptoms consist of discolored bark, similar to a canker, and some small vertical cracking in the bark. As time progresses, bark will begin to slough off, the death of the trunk and dieback. Symptoms can be seen on the south and southwest sides of the trees. The relationship between winter sunscald and bacterial canker of almond and peach in Chaharmahal va Bakhtiary province was investigated during 2016-2019. This study was conducted in 12 selected peach and almond orchards in different areas of the province. In almonds, disorder index on the southwest side of the trees increased by 83% compared to the northeast side of the trees, while in peaches the increase was about 82. 7%. Frequency of isolation of Pseudomonas syringae pv syringae (bacterial canker agent) on the southwest side of the trees was about 78. 4% and 75% higher for almonds and peaches, respectively. The southwestern white painting treatment of the trunk compared to the control showed that in almonds it decreased sunscald and canker symptoms in almonds70 to 81% and for peaches56. 3 to 86%. So, it can be said that winter sunscald is causes of decline and plays role as a predisposing factor for e bacterial canker of almond and peach trees in Chaharmahal va Bakhtiary province.

The cotton bollworm has been considered as a threatening pest in pistachio orchards in Kerman province especially in Sirjan. In this study, the nutritional indices of the third instar larvae reared on leaves and fruits of six pistachio varieties including Ahmad Aghaei, Akbari, Ohadi, Jandaghi, Kalehghochi and Momtaz. Experimental containers, containing one larvae and one fruit or leaf incubated at growth chamber with 22± 2° C, 55± 5% RH and a photoperiod of 16: 8 (L: D). The weight of larvae, feces and consumed fruits and leaves were calculated every 24 hours. Data were analyzed by one-way ANOVA using SPSS software. The results showed significant differences in all larval nutritional indices on studied pistachio varieties. The lowest values of efficiency of conversion of ingested food (17. 87± 0. 87%) and the lowest of efficiency of conversion of digested food (21. 73± 0. 69 %) were observed on fruits of Ohadi variety. Also, the lowest of efficiency of conversion of ingested food (11. 87± 0. 89 %) and the lowest of efficiency of conversion of digested food (15. 43± 0. 88 %) were observed on leaves of Ahmad Aghaei variety. Based on the cluster analysis resuls, the highest values of nutritional indices were observed in larvae feeding on fruits of Momtaz, Jandaghi and Kaleghohi varieties. The lowest values were obtained on larvae reared on fruit and leaf of Ohadi and leaf of Ahmad Aghaei varieties.

The Eulecanium tiliae is widely distributed in most parts of Iran, including western parts as a potential threat for different kinds of fruit trees. During 2016-2018, the morphology and biology of this pest was studied in natural conditions (Sahneh’ s cherry orchard). Sampling interval times were variable throughout the growing season. The reproductive adult females were collected and reared in laboratory condition and microscopic slides were made for species identification. Overwintering stage was as second nymphal instar on 1-2 years-old twigs. They have only one generation per year, This species appeared in considerable population on the twigs of individual cheery tree. Males were not found during the study of its life history. The reproductive female emerged in April, and began to oviposit from early May to early June. This species reproduce parthenogenetically. The number of eggs per female on, E. tiliae estimated, 570 (200-1000). The first instars appeared at the end of May, spread out and settled on both surfaces of the leaves.

Citrus bacterial canker is an economically important disease in many tropical and subtropical countries and caused by Xanthomonas citri subsp. citri. Several pathotypes of this pathogen have been described that primarily distinguished by their geographical origin, host range and certain genotypic characteristics Leaves, fruits and twinges samples of ‘ Mexican 'lime, with bacterial canker symptoms were collected from Kohgiluyeh and Boyer-Ahmad province in 2012. The bacterial strains were isolated from infected tissues using classic methods and primary identification of bacterial isolates was performed based on phenotypic characterization. Pathogenicity of isolates was approved on leaves of Mexican lime. Based on the disease symptoms, phenotypic and pathogenicity tests, PCR test by using specific primers and sequencing data of histidine kinase gene, the isolates were identified as Xanthomonas citri subsp. citri. This is the first report of the disease and the causal bacterium in Kohgiluyeh and Boyer-Ahmad province.

The genus Hexatylus Goodey, 1926 belonging to the family Neotylenchidae is distinguished from other members of the family with cephalic framework with eight sectors, the presence of strengthening rings around stylet, forked stylet at base, dorsal gland orifice near the base of stylet, lumen of esophagus joins lumen of intestine in region of nerve ring, esophagus glands overlap intestine dorsally, mono pro-delphic gonad in females, vulva as a transverse slit, close to anus, genital branch without post vulval sac, tail short, with sharp end and pointed tip. Goodey (1926) reported Hexatylus viviparus associated with diseased potato tubers in England. The nematode is spread worldwide and there are reports of this species in Europe, Asia and America. A population of this species was collected from the soil of potato fields in Chaldoran, West Azarbaijan province and the nematodes were extracted using combined sieving and centrifuge method and after killing, fixing, transferred to anhydrous glycerin. They were mounted on microscopic slides and the morphological and morphometrical characters studied using an Olympus AX70 optical microscope and digital images prepared by a connected camera to the microscope. The Iranian population of H. viviparus showed similarity to that of descriptions reported by Goodey, 1965, Nickle, 1968, Sumenkova, 1975 and Andrá ssy, 2007. Comparing the morphological and morphometrical characters of H. viviparus with Hexatylus mulveyi, the closest species to H. viviparus showed that number of lateral lines in H. viviparus is four while H. mulvey has six lines in lateral field. Also Nickle (1968) has not seen deirids in the studied specimens, but in the understudy population deirids are conspicuous. This is the first report of occurrence of H. viviparus for nematode fauna in Iran. The species has been found in various situations in which rotting plant material was present. It has been successfully cultivated on fungi plates. In our study, the nematode was collected from the rhizosphere of potato in which high densities of Alternaria sp. conidia was observed.