مجله دانش گیاه پزشکی ایران
سال چهل و هفتم شماره 1 (بهار و تابستان 1395)

The soybean cyst nematode (Heterodera glycine Ichinohe, SCN) is one of the most serious yields limiting pathogen on soybean (Glycine max (L.) Merr) which is found in many soybean–growing regions throughout the world. Applying of resistant sources is one of the efficient measures to manage this nematode. In this study, reaction of 63 soybean lines to the soybean cyst nematode were evaluated in field and growth chamber conditions. Host resistance was determined on the basis of female index (i.e., number of female developed on the tested lines / number of female on the standard susceptible cultivar Lee 74 as percentage). The results demonstrated that five lines were defined as resistant, whereas 14 lines with FI 10 to 29 were considered as moderate resistance. Subsequently, 22 lines were demonstrated as moderately susceptible and 22 lines were characterized as susceptible lines. The lines which showed resistance and moderate resistance in field conditions were selected for assay under control conditions. The results of pot experiments conducted under control conditions verified the field findings.

Take-all disease of wheat (Gaeumannomyces graminis var. tritici) (Ggt) is one of the most destructive root diseases in the world. It has not been introduced resistant genotype against this disease. In this study, 416 genotype of bread wheat, received from different location of Iran and other countries, were evaluated to take-all (T-41 isolate) in greenhouse conditions. Root dry weight, shoot dry weight, biological dry weight, amount of root and crown infection (disease score), disease index (DI), height, grain weight and number of seed were measured. Analysis of variance showed significantly different among genotypes. Winter genotypes are more resistant to take-all disease. Also in some genotypes, infected plants had root system more extensive and have produced additional roots and some infected genotypes of winter types were headed in the greenhouse without vernalization. Probably, this fungus have vernalization effect on some winter wheat genotypes. Root dry weight and disease index were and negatively correlated (-0.510***). The genotypes were classified into six groups on the basis of mean scores. The groups are; 11 genotypes were in highly resistant group (Sc = 0), 59 genotypes in resistant (0

The greenhouse whitefly, Trialeurodes vaporariorum Westwood (Hem.: Aleyrodidae) is a polyphagous and key pest that causes damaging to wide range of crops. The parasitoid wasp, Eretmocerus delhiensis Mani (Hym.: Aphelinidae) is a syn-ovigenic and thelytokous species that parasitizing greenhouse whitefly nymphs. In order to evaluation parasitoid wasp, Eretmocerus delhiensis Mani (Hym.: Aphelinidae) in control of greenhouse whitefly demography parameters of E. delhiensis on greenhouse whitefly on tomato cultivar Super-Chief at temperature 25±1°C, 65±5 % RH and a photoperiod 16:8 h (L: D) in growth chamber were studied. For calculation of population growth parameters Age- Stage, Two-Sex Life table was used. The result showed that oviposition period, longevity and fecundity for this parasitoid were 4.2±0.12 d, 20.74±0.5 d and 17.43±0.17 offspring respectively. Based on results of the life table, demography parameters consisting of net reproductive rate (R0), gross reproductive rate (GRR) were 12.11±0.94 and 31.43±1.85 offspring per female, intrinsic rate of increase (rm), finite rate of increase (λ), were 0.16±0.0059 d-1, 1.17±.007 d-1 and mean generation time (T) and doubling time (DT) of E. delhiensis were 15.66 d and 4.354/d respectively. Based on our results, this parasitoid is a promising candidate for greenhouse whitefly control.

The tomato leafminer, Tuta absoluta (Meyrick), is one of the most important pests of tomato, Solanum lycopersicum L., in Iran. In this research, natural enemies diversity of T. absoluta and proportion of predators or parasitoids density to moth eggs or larvae density on five tomato cultivars including Super Strain B, Super Chief, Mobil, Korral, and Early Urbana Y were studied in an experimental field during 2014 and 2015. In this study, ten predator species, four larval parasitoid species and one egg parasitoid species were collected and identified. Amongst the natural enemies, the predatory bugs Miridae and larval parasitoids Braconidae had the highest relative abundance. The Shannon diversity index for the complex of natural enemies was not significant among the five tested cultivars. The values of Morisita–Horn index for the complex of natural enemies among the five cultivars were calculated from 0.932 to 0.994. In two years, the greatest proportion of predarors density to moth eggs and larvae density (5.09% in 2014 and 6.44% in 2015), the highest proportion of larval parasitoids density to moth larvae density (3.92% in 2014 and 3.75% in 2015), and the greatest egg parasitoid density to moth eggs density (1.67% in both studied years) were recorded on Early Urbana Y. Therefore, it can be concluded that the cultivation of Early Urbana Y with increasing of the proportion of predators or parasitoids density to T. absoluta eggs and larvae density could be useful in the integrated management programs of the tomato leafminer in tomato fields.

Plant parasitic nematodes with various populations have found in the soil around the roots of plants. Due to the biologic value of landscape and the importance of plant parasitic nematodes in the reduction of the growth of landscape plants; the study of identification, abundance and distribution of plant-parasitic nematodes in landscape of Tehran city, Iran was in interest. In order to dentification of plant parasitic nematodes, 150 samples of rhizosphere of lawn and a variety of ornamental plants were collected in September and October 2013 from different landscapes in Tehran city. Soil samples were washed and nematodes were extracted, fixed, transferred to glycerin and slides were prepared. Morphological and morphometrical characters of the nematodes were evaluated microscopically according to references. As a result were identified 28 nematode species belonging to 19 genera. The genera Filenchus, Criconemoides, Helicotylenchus, Pratylenchus and Criconema had the greatest diversity of species in the examined materials. Among surveyed species, the most abundant were Helicotylenchus pseudorobustus, Filenchus afghanicus and Aphelenchus avenae by 57.3, 50.7 and 49.3 percent, respectively.

Determining the prevalence of saprophyte fungi in agricultural products and processed foods used in the poultry diet is important. These studies lead to an overall control plan and prevention of fungal infection in different stages of harvesting, transportation and storage. Most of Aspergillus species grow at ambient temperature. Some species can produce toxins in the diet of birds; thus, species identification is necessary to evaluate the mycotoxins contamination. For this purpose, 49 samples of poultry diets, including cannabis, purslane, corn, sorghum, cotton, corn, Italian millet, wheat, mixed grains, rice bran, Starter, Growth and Finisher were collected from Yazd, Lorestan, Mazandaran, East Azarbaijan, West Azarbaijan, Ardabil, Khorasan Razavi, Fars and Kerman provinces. Aspergillus contamination was investigated using the direct culture on potato dextrose agar, moist sterile filter paper and serial dilutiom methods.Appoximately,175 isolates of the Aspergillus were isolated. Based on morphological characteristics, A. japonicus, A. tubingensis, A. flavus, A. fumigatus, A. tamarii, A. ochraceus, A. parasiticus and A. terreus wereidentified. The wet filter paper method had higher efficiency in recovery and isolation of Aspergillus species. Aspergillus flavus was determined as the dominant species and Rafsanjan as the most contaminated region.

Genus Trichoderma is a monophyletic fungus which some their species is known as biocontrol agent. This study was carried out for phylogenetic analysis of some isolates of the genus Trichoderma. In this study 73 sequences (including 33 sequences from T. aspereluum, T. brevicompactum, T. capillare, T. harzianum, T. koningiopsis, T. pleuroticola and T. virens and 40 sequences obtained from GeneBank and ISTH) were used in phylogenetic analysis. The biomass of isolates grown in PDB was harvested by filter paper. The genomic DNA was extracted from mycelia after freeze-drying. The regions of ITS-rDNA, tef1/In2-3 and tef1/In4 were amplified using common and specific primers and then sequenced. The data analyzed using maximum likelihood (ML) algorithm through selecting the best-fitting nucleotide substitution model in MEGA 6 software. The results showed that all phylograms present relatively similar relationships for isolates among supported clades. In all gene trees except ITS-based phylogram, the isolates of T. koningiopsis and T. asperellum were positioned within a basal clade with strong bootstrap support. The tef1-based phylogeny showed a stronger supported clade for the species of T. brevicompactum, T.virens, T.koningiopsis and T.pleuroticola compere to ITS-based phylogeny. The tef1/In.4 based ML analysis generated supportive clade for Trichoderma isolates such as T. asperellum. This study confirms that tef1α/Intron4-based phylogeny provide reliable clustering for Trichoderma species.

Behavioral changes of biocontrol agents after exposing to pesticides have an important role in success of IPM programs. In the current study lethal and sublethal effects of abamectin, acetamiprid and indoxacarb as the widely used insecticides were investigated on adults of mirid bug, Nesidiocoris tenuis and its behavior on Tuta absoluta eggs. Experiments were performed in the laboratory conditions (25±1ºC, 60±10% R.H. and 16:8 (L:D) photoperiod). Effects of sublethal concentration of insecticides were evaluated during 24 h period using dried residues of insecticides on tomato leaf. The values of LC50 for abamectin, acetamiprid and indoxacarb against N. tenuis were 33.40, 36.55 and 204.43 and of LC30 were 20.42, 30.38 and 181.53 µl a.i./L, respectively. All insecticides decreased attack rate of the predator; however, the most effective one was indoxacarb. On the other hand, indoxacrab and acetamiprid caused significact increase in handling time of predator while the most effective was indoxacarb. Abamectin showed the lower behavioral effects among the tested insecticides. According to total effect index (E) in IOBC category, acetamiprid (85%) and indoxacarb (77%) were harmful against N. tenuis predatory bug, while, abamectin (38%) was considered as slightly harmful.

One of the crucial issues before the second cropping is having enough knowledge about the residue effect of first crop herbicides on second crops. This experiment was conducted to investigate the possible inhibitory effect of some selective paddy herbicides residues to second cropping. Experimental factors were included common paddy herbicides (thiobencarb, butachlor, oxadiargyl, bensulfuronmethyl, and non- herbicide control) and test plants (lettuce (Lactuca sativa L.) and cress (Lepidium sativum L.)). At first, herbicides were applied in paddy field and bioassay was carried out by using the soils of plots treated with those herbicides and test plants. Results showed that, in general, residual effect of paddy herbicides on the growth of second crops was different depending on plant type and herbicide. Compared with aerial parts, roots of the plants tested were more sensitive to residual herbicides. Butachlor showed the least (≤9%) and oxadiargyl the most (≥60%) inhibition on test plants, and bensulfuronmethyl and thiobencarb also had statistically similar inhibitory effect on the roots of the test plants. Based on results of this study, the growth of lettuce and cress as second crops in paddy fields could be significantly reduced by the residue of some paddy herbicides including thiobencarb, oxadiargy and Bensulfuronmethyl.

Activities of thirty bacterial strains obtained from plants rhizosphere in different areas against Phytophthora drechsleri were assessed through in vitro and greenhouse experiments. Dual culture and extracellular metabolites tests were used in in vitro assays. The bacterial strains inhibited growth of P. drechsleri, the highest inhibition zones was belonged to T17-4 strain with 61.904% in dual culture and VUPF760 strain with 57.87% in cell free metabolites tests. The highest and lowest reduction rates of disease severity were belonged to VUPF760 and VUPF506 with 68.75 and 16.66%, respectively. In the second section of the study, the ability of bacterial strains to induce peroxidase, polyphenol oxidase, phenylalanine ammonia lyase and phenolic compounds in pistachio seedling was investigated 3, 6, 12 and 24 days after inoculation. Bacterial strains increased enzyme activities that reached the maximum levels 6 days after inoculation with pathogen. The highest level of phenolic compounds was observed at 6 days after pathogen inoculation in treatments of bacterial strains and Ph. drechsleri compared with control. Induction of resistance in plants even 24 days after post-treatment with bacterial strains was effective for induction of more durable resistance compared to other activators of plant defense system. The ability of bacterial strains to increase enzymes activities and levels of phenolic compounds may be some of the mechanisms responsible for their biocontrol activities. VUPF760 strain showed the highest increase enzymes activities and levels of phenolic compounds.

Chemical control against overwintered adults of sunn pest Eurygaster integriceps Put. mostly has low efficacy. Today using insecticides and formulations that have durable toxicity on overwintered adults is more approved, because this strategy can reduce treated area against new generation. This research was conducted with six treatments and four replications in randomized complete block design against overwintered adults of sunn pest in Qazvin (Ismail Abad Agricultural Research Station) at 2007-2008. Emulsions and micro capsules formulations were applied with using motorized knapsack atomizer sprayer and with hands respectively. The treatments included delthametrin EC 2.5%, fenitrothion EC50%, fenitrothion G 5%, fenitrothion CS 20%, fipronil G 0.2% and check, that their effectiveness in controlling on sunn pest adults, new generation adults and nymphs were studied. The delthametrin EC 2.5% was more effective than the other treatments. Most treatments were not able to reduce damaged in the standard level (2%). Thus applying of pyrethroid insecticides such as delthametrin with micro capsulated suspension (CS) formulation can be more affected in chemical control of overwintered adults.

Citrus dieback and postbloom fruit drop caused by Colletotrichum gloeosporioides are common diseases of citrus trees in North of Iran. According to increasing of disease damage in recent years, which can be due to the genetical alteration of pathogen, genetic structure of the fungus population in North of Iran was studied. So, four citrus orchards in Rahim Abad (Guilan), Ramsar, Sari and Gorgan were surveyed and. symptomatic tissues were sampled. After identification of fungal Isolates, DNA fingerprinting for144 Isolates were done by seven ISSR markers and PCR method. Acording to cluster analyses by UPGMA method and Jacard coeficient, thirteen groups were found. The mean of gene and genotype diversities across all populations were 0.33 and 0.49 respectively. There were low genetic differentiation (0.127) among populations and high gene flow (3.437) proved the low genetic differentiation. Maximum genetic identity observed between Guilan and Gorgan and the minimum observed between Ramsar and Sari populations. Distance between Rahim Abad and Ramsar is less than between Ramsar and Sari. So, genetic distance between Guilan and Ramsar and between Ramsar and Sari populations correlated to their geographical distance, but it was irregular for Guilan and Gorgan isolates. According to this study C. gloeosporioides populations derived from citrus orchards in North of Iran have genetic diversity and low genetic differentiation and Genetic distance among populations confirm the high gene flow among them.

developmental time, reproduction, survival and sex ratio of predatory mite, Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) were evaluated when feeding on Tetranychus urticae Koch eggs in laboratory conditions at three constant temperatures (25± 1, 30±1 and 35±1°C), 70±10% R.H. and 16L: 8D h on strawberry leaf discs. Total developmental time of the predatory mite was obtained 41.16±0.97, 35.98±0.49 and 33.39±0.49 days at 25, 30 and 35 °C, respectively,. Developmental time of different stages decreased as temperature increased from 25 to 350C. The intrinsic rate of increase (r) was 0.14±0.01, 0.21±0.01 and 0.23±0.01 day-1, at 25±1°C, 30±1°C and 35±1 °C, respectively. There was significant difference among the intrinsic rates of increase at three temperatures. The net reproduction rate (R0) was 21.22±2.66, 17.34±2.20 and 16.31±2.19 offspring, at the mentioned temperatures. There was significant difference between the net reproduction rate at 25 °C and two other temperatures. Our results provide information about demography of A. swirskii feeding on T. urticae at three constant temperatures. These results showed that population growth of A. swirskii at
35 °C is better than other temperatures (25 and 30°C). These results can be used to compare population growth of predatory mite, A. swirskii, with other different temperatures or on other diets, for better use of this predatory mite, in biological control.

Greenhouse whitefly and two-spotted spider mite are two important pests on greenhouse crops. The polyphagous predatory mite Amblyseius swirskii preys on both of these pests. In this research, predation of the predatory mite on different stages of both pests, prey stage preference of pests, prey preference and switching behavior of predator between preferred stage of greenhouse whitefly and two-spotted spider mite were investigated in laboratory conditions (25 ± 1°C, 70 ± 10% RH and 16L: 8D hour photoperiod). The preference index for each experiment was calculated by Manly’s β index. Results showed that, young instars (first and second instars) of greenhouse whitefly and non-sessile stages of spider mites (larvae, protonymph and deuonymph) were preferred stages. Comparison of the mean preference index between young instars of greenhouse whitefly and protonymphs of two-spotted spider mite showed that this predator showed a significant preference to T. urticae. The variation in different ratio of preys had no effect on predatory mite preference so switching didn’t observed in A. swirskii.

Cotton aphid, Aphis frangulae gossypii Glover, is a major pest of cucumber in Iran. One of the important parasitoids playing role in population control of this pest in the fields and greenhouses is Lysiphlebus fabarum Marshall. In this study, we investigated sensitivity of different instars of cotton aphids and pupal stage of L. fabarum to field recommended and half-recommended concentration of three pesticides, acetamiprid, dichlorvos and azadirachtin by leaf dipping method. The persistence toxicity test and bioassays were also carried out on adult of parasitoid. Results revealed a significant reduction in the toxicity by increasing the nymphal stages of the aphid. These results also demonstrated the highest mortality for dichlorvos on pupal stage ofparasitoid. According to obtained results, LC50 of acetamiprid was 28.18, for dichlorvos was 7.052 and for azadirachtin was 1780.338, µg/lit on adult of parasitoid respectively. Based on IOBC categories, azadirachtin with stability of less than 5days, dichlorvos with stability 5-15 days and acetamiprid with stability between 15-31 days were classified as short lived (class A), slightly persistent (class B) and moderately persistent (class C), respectively. These results approved a better integration potential of azadirachtin with the parasitoid, L. fabarum, for aphid control.