Journal Of Crop Protection
Volume:9 Issue: 2, Jun 2020

The cosmopolitan root-knot nematodes of the genus Meloidogyne are considered as the most important plant-parasitic nematodes damaging almost all higher plant species. This paper provides an updated checklist of 105 valid species of Meloidogyne, along with their synonyms and non-valid members. Furthermore, species are grouped based upon their diagnostic characteristics of second-stage juveniles (tail shape, tail length, stylet length and dorsal gland orifice (DGO) distance from stylet base) and males (number of lateral incisures, stylet length, DGO and spicules length).

The western flower thrips (WFT), Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) is an invasive pest in greenhouse with high potential to cause damage to crops. There are a limited number of effective insecticides to manage this pest and several cases of chemical control failures have been reported in Iran which can be due to resistance to insecticides. To evaluate the status of insecticide resistance and possible resistance mechanisms, eight Iranian strains of F. occidentalis, collected from Tehran, Markazi, Alborz, Qazvin, Isfahan, Yazd (M and B) and Kerman provinces, were assayed against dichlorvos as a recommended insecticide for chemical control of thrips. Compared with the susceptible strain (Isfahan), two strains collected from Yazd had the lowest susceptibility to dichlorvos (Resistance Factor = 2.14 and 2.04 fold). Bioassay by synergists and enzyme assays demonstrated interfering of carboxyl esterase and glutathion S- transferase in Yazd M strain. The esterase inhibitor, triphenyl phosphite (TPP), and Glutathione S-transferase inhibitor, diethyl maleate (DEM), synergized the toxicity of dichlorvos in the Yazd M strain, (Synergistic Ratio = 5.28 and 1.79 fold, respectively). Also, carboxylesterase (for α- naphtyl acetate and ß- naphtyl acetate) and glutathion S- transferases activities in this population were 1.69, 7.31 and 0.97 fold higher than in the Isfahan strain. Furthermore, dichlorvos resistance did not significantly diminish after several months. Based on our results, we suggest that dichlorvos should be removed from the control program of this pest.

Despite successful lime witches'-broom (LWB) phytoplasma transmission by Hishimonus phycitis to the lime trees and Bakraee seedlings, there is no published document regarding LWB transmission by H. phycitis to lime seedlings. To study the possibility of vector-based transmission to lime seedlings, the feral leafhoppers were collected in LWB-infected lime orchards and caged on one-year old Mexican lime seedlings. Six months after inoculation, 50% of inoculated seedlings showed typical symptoms of LWB and were strongly positive in PCR assays. To our knowledge, this is the first report of transmission of Ca. P. aurantifolia to Mexican lime seedlings by H. phycitis under greenhouse condition.

The present study was aimed to investigate the effects of secondary metabolites produced by five Trichoderma spp. on the control of Fusarium wilt caused by Fusarium oxysporum f. sp. ciceris (FOC) in chickpea. In vitro biocontrol potentialities of Trichoderma spp. against FOC was tested. Trichoderma secondary metabolites were extracted by solvent extraction methods and evaluated against FOC. In vitro tests showed very good inhibitory effects by all Trichoderma spp. against FOC along with an inhibitory rate up to 73.8% and 27.8%, for direct and indirect contacts, respectively. Additionally, Trichoderma spp. caused a significant decrease in Fusarium wilt disease severity, in particular, T. polysporum showing 64.2% of disease severity reduction. The tested secondary metabolites were also effective against FOC with a significant decrease of mycelial growth from 6% to 76.9%. Similarly, in vivo tests revealed that secondary metabolites were very active in reducing disease severity. It was found that T. polysporum was the most active with 56.9% of disease severity reduction. Chickpea resistance is mostly attributed to polyphenolic compounds. The studied Trichoderma spp. and their secondary metabolites could be used as potential and promising antifungal agents in preventing the occurrence of Fusarium wilt in chickpea.

Curly top is one of the most important viral diseases of sugar beet. Use of resistance sources is a promising strategy for control of this disease. In the present study, the efficiency of four gene silencing constructs (OUT-hp، IN-hp، sense and antisense) against two major causes of curly top disease in Iran, beet curly top virus-Svr (BCTV) and beet curly top Iran virus (BCTIV), were evaluated in transgenic plants. Selection of transgenic plant seeds was carried out on selective medium 1/2MS containing glufosinate-ammonium (Basta) and the results showed that the pBCTV-IN-hp construct resulted in the highest germinated seeds. Selected plants were transferred to greenhouse and evaluated for resistance to basta and detection of silencing constructs in the transgenic plants. Afterwards, resistance of the selected transgenic plants to beet curly top viruses and resistance stability against cucumber mosaic virus (CMV) was evaluated in a completely randomized design with six treatments in a factorial experiment. The results showed that the transformed lines with each of four constructs were significantly different in severity of symptoms, plant height and number of flowering stems compared to their respective controls. Although these transgenic plants were resistant to BCTV-Svr and BCTIV, in their challenge inoculation experiments it was shown that this resistance was suppressed by CMV infection. 

Saffron is the most expensive agricultural product and like other products, is affected by some limiting factors, including soil pests such as bulb mite Rhizoglyphus robini Claparede (Acari: Acaridae). Due to its polyphagous habit, it remains in the soil for a long time and is one of the most important pests of saffron. To determine the effect of non-chemical management factors including soil solarization days, fertilization and year on the population of bulb mite and yield of saffron, a split-plot experiment based on a randomized complete block design in three replications was conducted between 2007 and 2011 in Gonabad, Iran. Fertilization (Cow manure) of zero, 20 and 40 t/ha as the main plots and soil solarization of zero, 10, 20, 30 and 45 days as sub-plots were studied for four years. The results showed that simple and interaction effects of the three factors including year, fertilization and soil solarization days on the population of bulb mite and saffron yield were significant. Simple linear regression was fitted between the population of bulb mite and saffron yield as well as multiple linear regression for population of bulb mite and saffron yield separately. The population of bulb mite increased during the experiment by increasing the two factors of the year and fertilization separately. Whereas, with increasing soil solarization days, population of bulb mite decreased except for 10 days solarization treatment and, unexpectedly, in 45 days of solarization treatment, the population increased in the fourth year.

In this study, 41 isolates of the genus Trichoderma including six species of Trichoderma arundinaceum, T. asperellum, T. atroviride, T. harzianum, T. longibrachiatum and T. virens were isolated from soils of cucumber fields in Kermanshah province, and their efficacy to control Phytophthora drechsleri, the causal agent of cucumber damping off, was investigated in laboratory and greenhouse conditions. In direct confrontation between Trichoderma isolates and the pathogen, all isolates were able to promote, establish, and sporulate on pathogen mycelia. Through dual culture test, the most inhibitory effect on pathogen growth (62.89%) was recorded for T. harzianum (isolate T1). Volatile compounds of T. harzianum (isolate T7) had the greatest mycelial growth inhibition (46.59%) compared with control. Complete growth inhibition of the pathogen was recorded when the growth medium was supplemented with culture filtrate of Trichoderma isolates at concentration of 15% and 30%. At the concentrations of 15% and 30%, 18 isolates and 22 isolates completely inhibited the pathogen expansion respectively. In the greenhouse, the results of data analysis on the survival percent of plants in various treatments showed significant differences between the isolates of Trichoderma in terms of preventing cucumber damping off. In conclusion, T. asperellum showed the highest ability to control Phytophthora damping off and promoting cucumber growth which is a new record for Iran. This species can be an appropriate choice for biological control of the disease caused by P. drechsleri in cucumber.

Trichogramma is an important genus of egg parasitoids that is frequently used as biological control agents against lepidopteran pests. The most widespread species of Trichogramma in Iran is Trichogramma brassicae Bezdenko that is widely used against rice stem borrer, Chilo suppressalis (Walker). In this study, the sublethal effects of LC30 concentration of diazinon and fipronil were studied on the functional response of T. brassicae to different densities (2, 4, 8, 16, 32 and 64) of Sitotroga cerealella (Olivier) eggs. The experiment was carried out in an insectarium at 25 ± 1 ºC, 70 ± 10% RH, and a photoperiod of 16: 8 (L: D) h. Young adult females of the parasitoid were exposed to LC30 of either insecticides for an appropriate time of exposure. Then, fresh host egges were offered to survived female wasps for parasitim for 24 h. The type of functional response was determined using logistic regression and the parameters including searching efficiency (a) and handling time (Th) were estimated by non-linear regression. The results revealed a type II functional response in the control and fipronil, and type III for diazinon. In this study, application of insecticides caused a decrease in the attack rate and an increase in the handling time of exposed wasps compared with the control. The longest handling time (3.76 ± 0.4 h) and the lowest attack rate (0.001 ± 0.0004) were observed in diazinon. The results suggested that the adverse effect of this insecticide on searching ability of T. brassicae should be considered in integrated pest management programs (IPM).

Trichoderma is very important as a bio control agent and probably a good alternative for chemical fungicides. Fusarium oxysporum is a plant pathogen that causes wilt in a wide range of plants. The use of gamma irradiation can be employed to increase Trichoderma efficiency against F. oxysporum. The induced mutation provides genetic changes in Trichoderma and in some of the mutated isolates the efficiency of bio control may be improved. In this study the efficiency of mutated T. harzianum CS5 against the F. oxysporum f.sp. radicis-cucumerinum was evaluated. Among 16 wild isolates of Trichoderma, CS5 isolate was chosen based on synchronous and nonsynchronous mutual cultivation with pathogen. The spore suspensions of T. harzianum CS5 were irradiated in a cobalt- 60 γ- irradiator at a dose rate of 0.23 Gy/Sec in Nuclear Agriculture Research School, (NSTRI, AEOI). Then antagonist screening of 76 mutants was investigated in the experiments of synchronous and nonsynchronous dual culture with pathogen. The results showed that only 17 mutants were able to control the pathogen better than wild type, and YFTM80 isolate had the most prevention. Using the ERIC-PCR marker, the distinction was investigated between the wild type and the 17 selected mutants. The results showed that the gamma ray is able to improve biocontrol efficiency of Trichoderma and the ERIC-PCR marker can differentiate among derived mutants, but it does not have the ability to distinguish mutants from wild type. In terms of antagonistic superiority, mutations might have occurred in antagonistic sites, which have led to improved antagonistic efficiency. Probably the ERIC-PCR marker has failed to replicate these areas.

We investigated the presence of Hop stunt viroid (HSVd) in apple samples, showing dappling fruit symptoms, in the Maragheh area (Northwest Iran) by means of RT-PCR. The viroid was detected only in leaves collected from symptomatic trees and a 298bp amplicon (IR-Gala) was directly sequenced in both directions. Multiple sequence alignment and Blast analyzes revealed that IR-Gala isolate shares the highest identity with grapevine isolates from Brazil and China. Amongst Iranian isolates of HSVd available in the GenBank, this isolate had the highest identity with grapevine isolate of HSVd from Maragheh region. In Phylogenetic analysis by MrBayes, IR-Gala was clustered with grapevine isolates from Brazil, China and Iran and may suggest that HSVd-apple isolate could be originated from grapevine.

Anthracnose disease caused by Ophiognomonia leptostyla, is the most important and widespread fungal disease on Juglans regia. Walnut disease symptomatic samples were collected from different provinces of Iran, during 2015–2016. Fungal isolates were identified based on ITS-rDNA sequence data. Variance analysis of colony growth rate (mm/day) and acervulus density on medium, was significant. Acervulus density on medium was strongly correlated with colony growth rate. The Max acervulus density was 60% and > 80% for Hamedan and Mazandaran isolates respectively. The virulence of six selected isolates was examined on cv. Chandler.</span> Virulence indices including spot diameter, disease severity, spot area average and logistic infection rate except spot number index, could successfully detect significant differences among isolates. SA-SE1 isolate from Mazandaran showed significantly the most virulence indices: disease severity (%), spot area and logistic infection rate. For the other five isolates, four significant levels in all virulence indices were observed. In summary after this isolate, other isolates including TA-ZY21, LA-SY21, U94-SR1, HA-GH22 and MA-K1 were placed in the next steps of virulence ranking. There was insignificant correlation between colony growth rate and disease severity. However, the acervulus density and disease severity were significantly correlated implying the importance of acervular conidial inoculum in secondary disease cycle progress. Disease severity was strongly correlated with number of spots, spot diameter and logistic infection rate. Disease severity was also negatively correlated with Mid-time (time to progress 50%). Moreover, there was positive relationship between logistic infection rate and three traits: number of spots, spot diameter and spot area average. This study was the first of the disease virulence components on cv. Chandler in Iran.

Two genera, Aneuropria Kieffer and Diapria Latreille and two species, Aneuropria foersteri (Kieffer, 1910) and Diapria conica (Fabricius, 1775) (Hymenoptera: Diapriidae) are recorded from Iran for the first time. The specimens were collected using Malaise traps from Hyrcanian forests of Mazandaran, Gulian and Golestan provinces in northern Iran. Diagnostic characters and geographical distribution of the newly recorded taxa are presented.

Three species of the genus Inostemma Haliday (Hymenoptera: Platygastridae), i.e. Inostemma discessus Szelenyi, I. koponeni Buhl and I. contariniae Szelenyi are reported as new records for the Iranian fauna. Inostemma discessus was reared for the first time from Ephedra gall midge, Ephedromyia debilopalpis Marikovskij (Dip.: Cecidomyiidae) on Ephedra sp. (Plantae: Ephedraceae) in the northwest Iran. The Iranian species of the genus Inostemma were listed.

The two-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae) is one of the most important pests of field crops, orchard trees and ornamentals around the world. The short life cycle, high reproductive potential, accompanied by frequent acaricide applications have caused resistance development to wide range of acaricides. In this study the susceptibility of two populations, collected from Karaj and Mahllat, was investigated against fenpyroximate. The bioassay test was carried out by using the leaf-dip method. The results showed that the LC50 values for Karaj and Mahallat population were 2.1 and 92 (mg/ml), respectively. The resistance ratio was 43.8. The enzyme assay results revealed that the activity ratios of esterase in Mahallat to Karaj populations were 2.5 and 1.2 when α-NA and β-NA were used as a substrate, respectively. The activity of cytochrome P450 in Mahallat population was 1.37 times higher than the Karaj population. There was no significant difference in glutathion S-transferase activity between the two populations. The gene expression (qRT-PCR) results showed that the expression level of CYP392A11 in Mahallat population was 3.52 times higher than Karaj population. These results suggested that esterase and cytochrome P450 monoxygenase are probably involved in resistance of T. urticae to fenpyroximate.

Since the beginning of the 20th</sup> century, several scientific names have been used for the causal agent of powdery mildew on evergreen spindle Euonymus japonicus</em>. The nomenclature of this powdery mildew is reviewed and using Erysiphe euonymicola</em> as current name for the species is suggested. Information on the history of occurrence, natural host range and distribution of E. japonicus</em> powdery mildew in Iran is provided. Morphological differences between E. euonymicola</em> and E. euonymi</em>, a powdery mildew on other species of Euonymus</em> in Europe is discussed.