Applied Entomology and Phytopathology
Year:2019 | Volume:87 | Issue:1 (108)|Papers Count:13

To evaluate the toxicity of Hottentotta saulcyi venom on Sesamia nonagrioides, we investigated the larval mortality, detoxification enzyme activity and histopathological alterations of the S. nonagrioides organs. Venoms were injected into the larvae at five doses (0. 15μ g, 0. 35μ g, 0. 5μ g, 0. 75μ g and 1μ g; fifteen larvae per each dose) and the doses causing death were recorded during the experiment. This study demonstrated that H. saulcyi venom was able to cause external symptoms that eventually led to death of the intoxicated larvae. Moreover, this venom strongly inhibited glutathione S-transferases (GST) activity. Our data highlighted the relationship between the activity of GST enzyme and larval mortalities, so that the inactivation of this enzyme by scorpion venom may be responsible for the increasing the larval mortality. In the present study, the damage of midgut epithelium and malpighian tubules has been directly visualized and documented using histopathology methods. Clear histopathological alterations of intoxication were observed for all larvae injected with 1μ g doses of venom, including a distinctive lysing and disorganizing of midgut epithelial cells that coupled with a progressive loss of the peritrophic membrane and the disappearance of microvilli.

The aim of this study was to compare the effect of Funneliformis mosseae mycorrhizal fungus on the activity of defense enzymes produced by Meloidogyne incognita attack on roots of tolerant and sensitive cucumber cultivars. For this purpose, an experiment was conducted in a greenhouse with four treatments and four replications in a completely randomized design (split design in time). Cucumber seedlings were planted in sterile soil. Mycorrhizal treatments were added to 75 grams inoculum per kilogram soil. 45 days after F. mosseae inoculation, 1500 J2 were added per each kilogram soil. The quantitative activity of peroxidase and polyphenol oxidase enzymes was measured after six and eigh days after inoculation. The results showed that the activity of the enzymes in inoculated with nematode increased in comparison with the control plants. In the inoculated with AMF alone, the average activity of enzymes in different days of measurement was higher than control and nematode treatment. In both cultivars, the activity of these enzymes increased significantly in nematode with mycorrhizal fungus. Totally, the activity of peroxidase and polyphenol oxidase enzymes in tolerant cultivar was significantly higher than sensitive in the same treatments and days of measurement which can be related to these enzymes roll in increasing tolerance to the nematode. Effect of mycorrhizal fungus on increasing the amount of defense enzymes in the treatments are considered as other results of this research.

Potato and onion are the most important commercial crops in Iran especially Isfahan province. Anthracnose caused by several species of Colletotrichum spp. In order to identify and determine the possibility of cross contamination among pathogenic species of each host to another host, sampling was carried out from potato and onion fields in Faraydan, Daran, Damaneh, Chadegan and Ashgerd regions from Isfahan province. Morphological characteristics led to 170 isolates of Colletotrichum that 120 isolates belonged to C. coccodes from potato and 50 isolates belonged to C. circinans from onion. 35 isolates of those 170 isolates were selected to amiliphy DNA using specific primers for the ITSrDNA region and sequencing. Pathogenicity test was conducted in greenhouse conditions. The results indicated the pathogenicity of C. circinans on onion After 30 days, but no symptoms were found on potato inoculated by thes isolates, while pathogenicity of C. coccodes was confirmed on potato after 60 days and no any symptoms was found on onion plants. The results might have used to control anthracnose in potato and onion fields.

Interaction among two isolates of Cucumber mosaic virus (CMV), Zin1 and Zin2 belong to CMV subgroup I and II was investigated on Nicotiana rustica plants in current study. Following singly and doubly mechanical inoculation of pure isolates on N. rustica plants, infection rate (frequency of detection) and relative concentration of each CMV isolate were calculated in six different time trials (days post inoculation, dpi) by quantitative ELISA. Statistical analysis of repeated measures data showed a meaningful effect (p<0. 05) of treatment and time variants on frequency of detection and relative concentration of each isolates. D/S ratio for each CMV isolate was less than 1 in doubly inoculation treatment. The results showed that the relative concentration of each isolate in singly inoculated plants was significantly (p<0. 01) more than doubly inoculated ones at 5, 10 and 18 dpi. The increase in virus titre at 18 dpi was confirmed by western blot analysis. These results demonestrated a cross-protection interaction among CMV subgroups. Variance analysis of data showed that unlike area under the disease progress curve (AUDPC) and concentration of chlorophyll, disease severity index (DSI), height and fresh weight of plants showed a significant difference among different tratments. In aphid transmission assays by Aphis gossypii fed on singly and doubly infected source plants, no significant difference was observed among transmission rate (T) and single aphid transmission efficiency (P*) of each CMV isolates.

Safflower capsule fly, Acanthiophilus helianthi is a serious pest on safflower, could reduce crop yield up to 25 %. To study the reaction of different safflower cultivars to safflower capsule fly in different planting dates, an experiment was conducted during three consecutive years (2006-2009) in split-split plot design with three replications, in Kaboutar-Abad research station (Isfahan, Iran). The main plot was spraying in two levels (sprayed and unsprayed), subplot was sowing date in 8 levels (from early March to late June) and sub-sub plot was cultivar in three levels (Arak, Soffe and Goldasht). Sampling was carried out in 5 times, according to the growth stages of safflower. In each sampling, percentage of infested heads, percentage of damaged seeds and number of larvae per head were counted. The results showed significant difference among planting dates for above three factors. The highest and lowest percentage of infested heads were recorded on late (late May to late June) and early planting dates (early March to early May), respectively. The highest and lowest number of larvae per head and the highest and lowest percentages of damaged seeds were observed on last planting date (late June) and early planting dates (early March to early April), respectively. Significant differences were found for the three factors among the studied cultivars. Goldasht cultivar had the highest percentage of infested head and percentage of damaged seeds. In order to control safflower capsule fly in the region, cultivation of Arak and Soffe cultivars in early planting dates (early March to early April) is recommended.

Archips rosanus (Linnaeus), is one of the most important pests of citrus trees in Mazandaran province. This study was conducted in two separate experiments in citrus orchards located in Maqrikola, Babolsar city. The first experiment was conducted to investigate the effect of mineral oil application in flowering time on the damage of this pest in a completely randomized design with three treatments including 1. 5% mineral oil, abamectin (EC 0. 8%) with a concentration of 750 ml/100L and control (without spraying) in three replications on 31th March 2016. The second experiment was conducted to investigate the effect of mineral oil application in flowering time on fruit production of citrus trees that were similar to the first one. The results of the first experiment showed that the number of infested shoots per tree were statistically different at 1% level (p <0. 01). The mean of infestation in control, abamectin and mineral oil treatments were 21. 33a, 9. 22b and 8. 89b infested shoots per tree, respectively. The results of the second experiment showed that the average amounts of fruit production were 128. 34a, 125. 54a and 122. 81a kg per tree in control, mineral oil and abamectin treatments respectively. Ttere was no statistically significant difference between them. The results of this study showed that application of mineral oil or abamectin in flowering stage has not harm effect on fruit production and it is able to control A. rosanus.

In this research, the faun of class Collembola was investigated in different regions of Kerman city and its suburbs during 2016‒ 2017. Several samples from soil and leaf litter were collected and extracted by Berlese funnels from these regions and Collembolan specimens were collected and separated. 22 species belonging to 18 genera, six families and three orders were identified. One genus Acheroxenylla Ellis, 1976 and two species Entomobrya indica (Baijal, 1955) and Drepanura kirgisica Martynova, 1971 are reported for the first time from Iran. Most species are new for Kerman fauna. The checklist of species with material examined and description of new record genus and species with illustrations were represented.

The relationship between population density of sunn pest and kernel damage percentage, especially in natural farmers’ situations, determines a criterion for the economic injury level (EIL). For this purpose three wheat farms, cultivated with either Sardari or Azar2 varieties were selected in each of Lorestan and West Azarbaijan provinces. Population densities of nymphs and new adults were sampled both by quadrat and sweeping net sampling methods (each using twenty-five 20-squer-meter plots) during the last month of wheat growth. Then, at harvesting 10 wheat spikes were randomly taken off from each plot to determine kernel damage percentage. The relationship between population density and kernel damage percentage in each plot was determined, using correlation and regression analyses. Linear and nonlinear models were also fitted using TableCurve 2D software. As a result, exponential models were properly fitted for Sardari variety in both quadrat and sweeping net methods, respectively, whereas power and exponential models were well matched with Azar2 variety for the respective methods. Based on the models prediction, mean population densities that could cause 2 percent kernel damage in Sardari and Azar 2 varieties were 3. 25 and 2. 88 for quadrat and 4. 3 and 2. 82 for sweep net, respectively. Moreover, the EILs of the nymphs and new adults for different kernel damaged levels were discussed.

In this study, the effect of the low doses of gamma irradiation (10, 20, and 30 Gy) alone and in associated with the salicylic acid and indirect temperature on the seed borne infection of Bean common mosaic virus (BCMV) was assessed. Commercial bean seeds called “ Sadri” with seed borne infection to BCMV were sowed. The seedlings were tested for the infection of BCMV by indirect plate-trapped antigen (PTA-ELISA) test and seeded. Results indicated that the growth factors in the irradiated seeds alone and in associated with the salicylic acid or indirect temperature significantly increased (P≤ 0. 05) in healthy and infected seedlings compared to the non-irradiated seedlings. Gamma irradiation induced the specific activity of various antioxidant enzymes (PPO, POX, CAT and PAL) as well as the total protein density in treated healthy and infected beans, and decreased the concentration of BCMV proteins in the infected and irradiated seeds alone and so in associated with the salicylic acid or indirect temperature compared to the non-irradiated seedlings. Results of this research indicated to the induction of the relative resistance against BCMV in infected bean seedlings treated with the 20 and 30 Gy doses of gamma irradiation alone or in associated with the salicylic acid and indirect temperature.

In the summer of 2018, viral symptoms corresponded to Strawberry mottle virus (SMoV) in some strawberry fields were observed and 48 leaf samples/plants were collected from different fields from Kurdistan Province. In the preliminary test, some samples were inoculated to Fragaria vesca by strawberry aphid (Chaetosiphon fragaefolii) and SMoV-symptoms were observed after about two weeks. Then, total RNA of samples was extracted by silica-capture method and subjected to cDNA synthesize with random hexamer primers. RT-PCR was done by specific SMoV pair primer and amplified fragments were observed on 1. 2% agarose gels. RT-PCR results were showed that 28 out of 48 samples were infected by SMoV. Based on the geographical origin, cultivar and symptoms, five isolates were selected, ligated to pTG-19 and transformed to Escherichia coli. Recombinant plasmids were sequenced and analyzed for molecular characterization and phylogenetic studies on SMoV 3΄ NCR. Mean genetic distance between the isolates from Iran was 0. 005 ± 0. 002 but between these isolates and the other isolates available in GenBank was 0. 084 ± 0. 008. The highest and lowest genetic distance was found between K3 with NSper51 (0. 093 ± 0. 008) and SQA/AG with NB926 (0. 019 ± 0. 017) from Canada, respectively. This is the first report on occurrence of SMoV on strawberry in Kurdistan Province.

In the present study, sublethal effects of Metarhizium anisopliae (LC30) on Aphis gossypii were evaluated at three constant temperatures of 20, 25 and 30 º C, relative humidity of 65 ± 5% and a light period of 16h. Data analysis was performed using Age-stage two sex life table procedure. The lowest duration of immature stages for A. gossypii was estimated at 25 º C (4. 37 day). The highest recorded value for female longevity was also recorded at this temperature (16. 73 day). Different temperatures had significant effects on total fecundity of treated individuals with sublethal concentration of M. anisopliae and the lowest recorded value for this parameter was obtained at 30 º C (3. 60 nymph). Furthermore, sublethal effects of M. anisopliae on population growth parameters of offspring from treated individuals were also significantly different at temperatures tested. Since the recorded value of birth rate was dramatically lower than death ones at 30 º C, the estimated value for intrinsic rate of increase (r) showed a negative value (-0. 091 day-1) at this temperature. The estimated values of net reproductive rate (R0) at 20 and 30 º C (5. 46 and 0. 47 offspring/individual, respectively) were significantly lower than recorded value for this parameter at 25 º C (66. 29 offspring/individual). The results obtained revealed that temperatures of 20 and 30 º C significantly affect pathogenecity of M. anisopliae to A. gossypii. Our findings could increase the efficiency of M. anisopliae in management programs of different pests.

Rice sheath blight disease caused by Rhizoctonia solani AG-1 IA has been recognized as a major damaging factor in many rice regions of the world. The aim of this research was investigatingon the effect of two isolates of Pseudomonas protegenes, antagonistic and inducer isolates alone and in combination with potassium silicate on expression rate and production of chitinase, β-1, 3-gluconase and peroxidase enzymes at 0, 6, 12, 24, 48 and 72 hours after inoculation of Fajr cultivar with the causal agent of rice sheath blight disease. The amount of 1000 and 200 mg of sheath-leaf tissue was prepared as powdered in liquid nitrogen and thenin sodium acetate and phosphate buffers respectively to measure chitinase, β-1, 3-gluconase and peroxidas eenzymes and 100 mg of the powder in RNAX-Plus solution to study the genes expression and RNA extraction. The amount of β-1, 3-gluconas eenzyme in 72 hours and chitinase enzyme in 48 hours of infection was at maximum level. As regards, compared with other treatments, the highest level of expression of the genes for chitinase and peroxidase was observed in treatment of antagonistic bacteria in combination with potassium silicate in the early hours of the pathological process, 6 hours after inoculation with the fungal agent, and β-1, 3-gluconase reached the maximum at 24 h, Thus this treatment recognized as the best treatment.

Chickpea chlorotic dwarf virus (CpCDV, genus Mastrevirus, family Geminiviridae) is one of the most important viral agents which associated with yellowing symptom in the chickpea fields. During the surveys, 2015-2016, 248 chickpea and lentil plant samples showing yellowing symptom were collected from five provinces: Lorestan, Kermanshah, Zanjan, East and West Azarbaijan, in Iran. The samples were tested to CpCDV infection, using TBIA and positive samples in TBIA were tested by PCR. Total DNA of positive samples were extracted and enriched using rolling-circle amplification (RCA). RCA products were restricted using Xho I enzyme and yielding products of ~2. 5-6 kb. These fragments were used for polymerase chain reaction (PCR), using specific primers for RepA protein of CpCDV. PCR amplicons with an expected size of ~960 bp were amplified, cloned and sequenced. TBIA and PCR results showed the presence of CpCDV infection in all surveyed provinces with the highest infection in chickpea plants. Nucleotide sequence comparisons showed that Iranian isolates shared the highest identity to strain A, D and F from India, Pakistan, and Yemen. Phylogenetic anlyses showed that Iranian CpCDV strains were grouped with Sudan, Morrocco, India, and Pakistan (strain D, group III), Sudan, Oman, Yemen, and Pakistan (starin F, GroupIV), and Tunesia, Egypt, Syria, and Turkey (strain A, group V).