نشریه آفات و بیماریهای گیاهی
سال نودم شماره 2 (پیاپی 115، اسفند 1401)

A new species of the genus Ektaphelenchus, E. golestanicus n. sp., is described and illustrated based on morphological and morphometric characteristics. The new species was isolated from dead wood samples collected from natural forests in Golestan province, northern Iran. E. golestanicus n. sp. is mainly characterized by 347-378 μm long females (the currently shortest representative species of the genus), having three lines in lateral field, slightly offset cephalic region flat in the anterior end, well-developed stylet, 15.1-16.6 μm long, having a wide lumen and lacking basal knobs or swellings, excretory pore slightly more than one metacorpus length posterior to it, functional rectum and anus absent, posterior body region (tail) conical, narrowing towards the end, males with single precloacal papilla (P1), the second cloacal pair (P2) apparently lacking, and paired third caudal papillae (P3), arcuate and separate spicules 7-10 μm long along arc line with well-developed wide condylus, and tail with a small mucron at the terminus. The new species was morphologically compared with typologically similar small-sized species of Ektaphelenchus having three lines in the lateral field, conical posterior body end and stylet lacking basal knobs, namely E. apophysatus, E. joyceae and E. taiwanensis. It was further compared with E. goffarti and E. olitorius having a similar female posterior body end shape and unknown number of incisures in the lateral field, as well as Seinura informis and S. paratenuicaudata due to having obscure rectum and anus.

Low-cost physical methods were evaluated in oilseed rape farms of Golestan and North Khorasan provinces. Experiments were conducted in 400 m2 plots using Completely Randomized Block Design with three replications. Treatments were consisted of: 1. Spanish tape, (EcoBirdNex), 2. Large white plastic bags, 3. white nylon tape, 4. Nylon thread with white yoonolit pieces, 5. Plastic tube, 6. Control (no treatment). In autumn 2019 and 2020, samplings were conducted using ten quadrates of 1×1 m2, 1, 2, 3 and 4 weeks after treatments. Total number of damaged and undamaged plants were registered and the percentage of damaged plants was calculated accordingly. Treatments showed significant difference with control and effects of treatments was significant in North Khorasan and in Golestan (P<0.05). Effects of weeks was significant in Golestan in both years, and in North Khorasan in 2019 (P<0.05). In view of preparation of treatments and economic costs, treatments of plastic bags and Spanish tape were effective and applicable with two functions of physical sight barrier and making nuisance simultaneously, with no harm on the environment.

Olive fruit fly Bactrocera oleae (Rossi) (Dip.: Tephritidae), is the main and considerable damaging pest on olive trees (Olea europaea, Oleaceae) and causes huge economic losses. In this study, the effect of temperature on developmental rate of the Olive fruit fly was studied at 7 constant temperatures,10, 15, 20, 24, 28, 32, and 35 °C, 60-70% RH, and a photoperiod of (L:D) 16:8h. 26 nonlinear models were evaluated to determine development rate of olive fruit flies at different temperatures and to estimate the thermal developmental thresholds.Among evaluated nonlinear models, Lactin-2 and Briere-2 were the best fitting models for all immature stages considering the statistical criteria and biological significance of the estimations. Accordingly, the lower temperature threshold values (T0) estimated using Briere-2 model for incubation period, egg+ larval period, pupal period and the total period of immature stages, 5- 5.001, 5- 9.16, 7.19- 9.76, and 7.69- 8.68 °C respectively. In addition, the values of the upper temperature threshold (TU) for the mentioned developmental stages estimated 32- 43.42, 32.04- 36.23, 32.03- 36.42, and 34.03- 34.4 °C, respectively. Furthermore, estimated values for the optimal temperature (Topt) for the same mentioned developmental stages were 27.99- 30.09, 24.43- 28.04, 25.82- 30.32, and 25.94- 26.86 °C, respectively. Finally the values of lethal temperature threshold (Tl) for the mentioned developmental stages by using Lactin-2 model estimated as 34.31- 43.8, 37.44- 39.53, 33.67- 45, and 37.93- 40.13°C, respectively. The findings of the present study are useful for predicting the population dynamics of olive fruit flies and can be effective in developing optimal management strategies of B. oleae.

Codling moth, Cydia pomonella Linnaeus (Lep.: Tortricidae), is the most important pest of apple orchards, feeding on fruits, resulting to reduce the quantity and quality of product. In order to reduce the use of chemical insecticides, the application of kaolin particle film was tested in the fields of tree regions of Iran (Tehran, Razavi Khorasan, & Zanjan regions). The different concentrations, 3, 4 and 5%, of kaolin clay (Sepidan® WP95%), and diazinon (Diazinon® EC60%) and fozalone (Zolon® EC35%) insecticides were sprayed over the whole canopy, three times from early June to late August. Based on the field studies, kaolin-5% had a similar efficacy to chemical insecticides. The mean of codling moth infestation in fozalone, diazinon and kaolin-5% treatments were 14, 16 and 16.4%, respectively, compared to the control (44.6%). The use of kaolin increased the weight and diameter of the fruits and the chlorophyll index and photosynthesis amount of the apple trees. In the kaolin-5% and control treatments, the mean fruit weight were 247 and 146 g, and the mean fruit diameter were 78.6 and 75 mm, respectively. Also, the chlorophyll index was 53.8 and 51.5, and the photosynthesis rate was 5.91 and 4.93 μmol/m2/s, respectively. Therefore, due to the high effect of kaolin in reducing of pest damage and also no adverse effect on trees, spraying kaolin (Sepidan® WP) at the concentration 5% over the whole canopy, before the peak of moth oviposition, can be used successfully to reduce codling moth on apple.

During 2018 and 2019, a survey was carried out on the detection of bacterial crown gall disease on plum, sweet cherryDuring 2018 and 2019, a survey was carried out on detection of bacterial crown gall disease on plum, sweet cherry and apple trees in Urmia, Khoy, Salmas and Naghadeh in West Azarbaijan province. In total, 32 isolates causing gall on the crown of tomato seedlings were selected to identify further characteristics. Pathogenic strains were gram-negative, motile, and aerobic. In some of the phenotypic characteristics, differences were observed compared to the previous reports. These results indicate the existence of heterogeneity among Iranian strains. Molecular identification of strains was based on virD2, ipt, and virC genes using four specific primer pairs. The results of this research showed that the tested stone and pome fruit trees were infected with Agrobacterium tumefaciens No interference was observed in the function of the mentioned primers in the multiplex polymerase chain reaction. Thus, this accurate identification method is recommended by saving time and consumption of molecular materials.  .

Spatial distribution of the English grain aphid, Sitobion avenae (F.), was studied in wheat fields of Mahidasht, Kermanshah province and Sequential sampling models with fixed precision level were prepared for its monitoring. Sampling was conducted during five years. At each sampling date, 100 tillers were randomly visited. The mean range of population density in wheat field was 0.39-34.01 aphids/ tiller. Taylor's Power Law parameters were used to preparing sampling models according to Green (1970). Spatial distribution was determined as cumulative. Sample size decreased with increasing aphid population density in sampling models. In research precision level of (0.1), the sample size required at the highest average population density observed in the field (34.01/ tiller) was 136, which in precision level proposed for integrated pest management (0.25) reduced to 22 tillers. Overall, due to the large sample size at the precision level of 0.1, the model prepared at the precision level of integrated pest management (0.25) was recommended for monitoring S. avenae. The recommended model can reduce sample size more than six times at different densities in comparison to the sequential sampling model at the precision level of 0.1.

Septoria tritici blotch (STB) is one of the major diseases on wheat in most regions of the world where there is moderate temperature and high relative humidity. In this study, the virulence pattern of STB isolates collected from the Moghan region was identified on differential genotypes during two consecutive years of 2020 and 2021. To identify new sources of resistance, adult plant reaction of 53 elite wheat lines to the pathogen populations was studied in research station fields of Ardabil agricultural and natural resources research and education center (Moghan) using the parameters of percentages of the relative height of disease progress on plant as well as disease severity, where the seedling response of the genotypes was evaluated as percentages of necrotic leaf area as well as necrotic area bearing pycnidia under greenhouse conditions in a randomized complete block design (RCBD). Based on the results, high virulence could be observed on the resistance genes Stb3, Stb4, Stb7, Stb8, and Stb9, whereas avirulence was recognized on Stb11 and Stb18 in both years. Cluster analysis of wheat genotypes for resistance components against Moghan populations of Z. tritici has led to three main groups of resistant, moderately resistant to moderately susceptible, and susceptible. About 19% of elite wheat lines including DM-95-6, D-96-16, DM-95-16, D-96-5, D-96-19, N-94-12, N-95- 10, N-96-15, CD-96-9 and N-95-7 showed acceptable levels of resistance in different growth stages during two years.

In this research, the effect of the intracellular symbiotic Wolbachia bacteria on attack rate (a), handling time (Th) and emergence rate of Wolbachia infected asexual (A), natural bisexual (B) and cured bisexual by antibiotic (CB) strains of Trichogramma brassicae was studied under laboratory and cold storage conditions. The evaluation of functional response of the Trichogramma strains exposed to different densities of Ephestia kuehniella eggs revealed type II, and no significant difference was observed between the attack rate and their handling time. Based on the results of short-term cold storage, the hatching rate of all three populations reared at 20°C was higher than populations reared at 25°C, and statistically had a significant difference. However, in similar storage periods, the populations infected (A) and non-infected (B and CB) were in the same groups with no significant difference in terms of the emergence rate. According to the results of this study and previous findings, by providing optimal conditions for reproduction and maintenance of Wolbachia infected lines, the use of thelytokous Trichogramma wasps would be more economical compared with natural sexual populations, which is discussed in this article.