Applied Entomology and Phytopathology
Year:2009 | Volume:76 | Issue:2 (86)|Papers Count:14

In order to study presence, distribution and importance of mating types of the fungus Mycosphaerella graminicola (Fückel) J. Schröt in Cohn (anamorph Septoria tritici Roberge in Desmaze.) causative agent of septoria leaf blotch, fifty eight isolates were collected randomly from wheat fields of Golestan, Mazandaran, Ardabil, Ilam, Khozestan, Kermanshah and Fars provinces of Iran, during 2005. DNA was extracted based on standard protocols. Multiplex PCR was conducted using two mating type primers viz MAT 1-1 and MAT 1-2. Results showed that 29 isolates produced MAT 1-1 idiomorph with 340 bp molecular weight and 29 isolates produced MAT 1-2 idiomorph with 660 bp molecular weight. Both idiomorphs were detected in all locations. Chi-square analysis showed that two mating types have 1:1 ratio and strongly suggests that sexual reproduction of the fungus occurs in Iran. The pathogen with both sexual and asexual reproductions will have potential to overcome rapidly the race specific resistance sources. Therefore, it would be desirable to use cultivars with race non specific resistance genes.

Due to increasing attacks by Nysius cymoides, False Chinch Bug (FCB), in the canola fields of Iran, attempts have been made on its different control measures. Use of attractants might be a promising method in this relation. Behavioral effect of a synthesized isothiocyanate attractant was studied on FCB adults under laboratory condition. Ethyl 4- isothiocyanatobutyrate (ETCB) was synthesized via two-step reaction sequences from starting material of 4-aminobutyric acid with exposure to HCl gas, following the treatment of resulting ester with 1,1`-thiocarbonyldiimidazole. This technique is a newly modified procedure whose comparison with the commonly used technique is discussed. Although the synthetic attracted both sexes in a two-choice pitfall olfactometer, it was more efficient on the female FCBs.

This checklist provides faunistic data for 19 species belonging to 6 ichneumonid wasps: Anomaloninae, Cremastinae, Ctenopelmatinae, Mesochorinae, Metopiinae, and Orthopelmatinae, of which, 3 species from Anomaloninae, 4 species and 2 genera (Cremastus and Trathala) from Cremastinae, 1 species and 1 genus (Mesoleius) from Ctenopelmatinae, 2 species from Metopiinae and 1 species from Orthopelmatinae are newly recorded for the Iranian fauna. A brief check list of the previously recorded species of these subfamilies from Iran is provided. The present work increases the number of the Iranian species of Anomaloninae, Cremastinae, Ctenopelmatinae, Metopiinae, Orthopelmatinae, and Mesochorinae to 9, 7, 2, 5, 2, and 1 respectively.

Current research is conducted to evaluate effects of Lecanicillium muscarium (Petch) Zare & Gams (Deut.: Moniliales) on longevity, fecundity and mating behavior of Aphidius nigripes Ashmead (Hym.: Aphididae). Different levels of infection established by spraying two fungal concentrations (105 and 107 spore/ml and control with distilled water) or with sampling in different time on the male or female parasitoids. Based on different experiments, possibility of fungal transmission during mating, survival, parasitism rate, sex ratio, weight of progeny, time before mating and time of mating were evaluated.Results demonstrated that there was no transmission of fungus from infected to healthy individuals during mating. Also, there were not any significant differences in survival of healthy females, parasitism rate and sex ratio of progeny between treatments and control, when infected males mated with healthy females. Infection of females after 96 hours, (mated with healthy males) showed that there is significant effect on theirs survival (Treatment 6.61 ± 0.94 and control 10.7 ± 1.48) and parasitism rate (treatment 106.7 ± 16.6 and control 161 ± 16.4). Whereas, sex ratio and weight of progeny in treatments were similar compared with control. Fungal infection was effective on mating behavior of infected male parasitoids. Three and four days after inoculation, necessary time for mating of infected males with healthy females significantly increased, compared to control (163.8± 21.8, 205.1±18.8 and 119.6±21.04 seconds for treatments and control, respectively). The infected and control females started to mate healthy males at the same time and their mating durations were equal.

Eighteen wasp species either primary or secondary parasitoids develop on the pistachio twig borer moth, Kermania pistaciella Amsel (Lepidoptera: Tineidae: Hieroxestinae) in the pistachio plantations of Kerman province, southern part of Iran. Thirteen species have already been reported (Achterberg and Mehrnejad, 2002, the braconid parasitoids of Kermania pistaciella Amsel in Iran, Zoologische Mededelingen Leiden; Mehrnejad, 2008, The primary and secondary parasitoids of the pistachio twig borer moth, Kermania pistaciella Amsel (I), Appl. Ent. Phytopath.), however the remaining 5 species are being introduced as follow…

Schizotetranychus celarius or Bamboo spider mite was collected for the first time from Dracaena sanderiana Sander ex Mast. in samples received from Plant Protection Organization and is reported as mite pest of ornamental plants in Iran. This mite observed on Salix matsudana in Tehran province during 2006 its spread seams to be due to lack of quaratine rules' consideration by private sector. Feeding, different life stages and high populations of this mite were observed under webs in depressions situated on leaf underside. These depressions appeared as yellow or white spots on the opposite side. The damage was most sever on leaves situated on lower parts of the trees…..

270 actinomycetes were isolated from soils of various regions of Iran including Khuzestan, Esfahan, Gilan, Hormozgan, Mazandaran, Tehran and Azarbayejane Gharbi provinces using special media. Inhibition effects of their extracellular broth were assessed against Fusarium oxyosporum, Aspergillus niger, Alternaria alternata by top agar layer method. 28 isolates showed antifungal activity against at least one of the fungi tested with more than 20mm diameter of inhibition zone and 5 isolates had more than 30mm diameter of inhibition zone. Isolate #35 demonstrated 10%-42% growth inhibition against all of the fungi tested and selected for further investigations. The effect of 3 seeding and 5 fermentation media on production of antifungal compound by this strain was assessed by cylinder diffusion assay method. The results showed that culture filtrate obtained from seeding medium 2 and Hicky-Tresner fermentation medium had maximum inhibition activity against three tested fungi. So, these media are proposed as suitable media for growth of the strain (inoculums preparation) and production of antifungal agent, respectively. Studies on molecular, morphological and biochemical characteristic of this isolate and 16S rDNA gene nucleotide analysis showed that isolate #35 had maximum similarity to Streptomyces cuspidosporus DSM41425. But significant differences in morphological and biochemical characteristics between this species and isolate #35 showed that further investigations are needed for determination of its species.

In order to study the competitive ability of onion against Nettle-leaf goosefoot (Chenopodium murale), an experiment was conducted at the research center of Iranshahr during 2003 and 2004. The experimental design was split-plot based on Randomized Complete Block Design (RCBD) with 4 replications. Main plots were planting systems (direct-seeded and transplanted) and sub plots were five density patterns (0, 0.33, 1, 3 and 6 plant/m2) at fix density of onion. The relationships between onion yield and Nettle-leaf density for each year were described using a rectangular hyperbolic function suggested by Cousens. The initial slop of the hyperbola (parameter I), representing the percentage yield reduction per unit density for very low Nettle-leaf infestations, was estimated 66.86 and 23.89% for direct-seeded onion and transplanted onion in 2003 while 48.09 and 42.86% in 2004. Maximum yield loss (parameter A), was estimated 92.92% in first year and 80.95 in second year for transplanted onion. In direct-seeded that have less competitive ability than transplanted onion, A, was 100% in two year. Generally, the results from experiments data and regression model showed that nettle-leaf is more competitive than onion.

The false chinch bug, Nysius cymoides, has threatened canola plantation since a crowd of bugs swarming out into the adjacent fields upon the plant harvesting. In order to study its biology and demography under laboratory conditions (T = 24 ± 1°C; R.H. = 60-70% and L:D = 16:8 h), individuals from a colony originated from Nowzarabad (Neka, Mazandaran province) were used. Newly laid eggs were placed in small petri dishes (6 × 1 cm) and provided with water and canola seeds (Option variety) till adulthood. Nine pairs of adults were separately confined in 0.3 l transparent plastic containers. Every day, they were provided with water and rape seed, and monitored to check hatching, moulting, mortality and oviposition. Results showed that incubation period and five nymphal stadia were: 8.11 ± 0.07, 8.36 ± 0.25, 5.31 ± 0.18, 5.95 ± 0.48, 5.53±0.41 and 6.83 ± 0.51 days, respectively. Total developmental times of the immature stages of females (37.00 ± 1.55 days) and males (36.89 ± 1.24 days) were not significantly different. Among nymphal stages, first instars had the highest mortality. The bug could produce many continuous generations without entering diapauses under the studied conditions. Preoviposition period was 4.0 ± 0.29 days. Gross, GRR, and net reproductive rates, Ro, were 126.17 and 32.86 female eggs, respectively. Otherdemographic parameters such as intrinsic rate of increase, rm, finite rate of increase, l, generation time, T, and doubling time, DT, were: 0.07172 and 1.07436 (female/female/day), and 48.69 and 9.66 days, respectively.

The Citrus Leafminer (CLM), Phyllocnistis citrella Stainton, is naturally known from most of citrus orchards in Iran. However it is not generally considered as a major pest. Thereare different natural enemies which significantly control the population of P. citrella, including the following nineteen species of eulophid parasitoid wasps which were collected on CLM larvae from various parts of Iran.Cirrospilus ingenuus Gahan, C. lyncus Walker, C. viticola (Rondani), C. staryi Boucek, Elachertus gallicus Erdos, Hyssopus geniculatus (Hartig), Pnigalio soemius (Walker), P. agraules populifoliellae Erdös, Stenomesius rufescens (Retzius), Neochrysocharis Formosa (Westwood), Pediobius crassicornis (Thomson), P. italicus Boucek, P. pyrgo (Walker), P. saulius (Walker), Baryscapus conwentziae (Ferrière), B. endemus (Walker), B. oophagus (Otten), Citrostichus phyllocnistoides (Narayanan), Tamarixia upis (Walker).

To study Fusarium species associated with potato dry rot during October 2001-April 2002, samples from stored potatoes were collected from Ardabil, Tehran and Hamedan provinces. Decayed segments were cultured on potato dextrose agar. Species were identified based on morphological characters. A total of 208 isolates obtained belonging to Fusarium acuminatum, F. culmorum, F. equiseti, F. lateritium, F. oxysporum, F. sambucinum, F. solani, F. reticulatum and F. verticillioides. This is the first report of F. culmorum and F. reticulatum as the causal agent of potato dry rot in Iran. The prevalence of isolated species in descending order for Ardabil Province was F. equiseti, F. sambucinum, F. oxysporum, F. solani, F. culmorum, F. lateritium and F. verticillioides; for Tehran Province was F. oxysporum, F. solani, F. equiseti, F. sambucinum and F. reticulatum and for Hamadan Province was F. sambucinum, F. acuminatum, F. solani, F. oxysporum, F. equiseti and F. reticulatum. A conidial suspension (1×104 conidia/ml) for each isolate was inoculated on potato tubers. Isolates of F. solani were the most pathogenic while those of F. reticulatum had the lowest pathogenicity. F. sambucinum, F. oxysporum and F. solani were the most pathogenic species in all three provinces, whereas F. equiseti and F. acuminatum, were respectively important in Ardabil and Hamedan Provinces.

Birds are considered as important key pests of sunflower. This survey was conducted in Karaj & Khoy regions during the summer of 2003 and 2004. In this experiment, 1309 heads of sunflower were randomly selected and damage rate were estimated in sunflower fields of agricultural research stations of Karaj and Khoy. Mean damage rate in Karaj was 45.3%, while in Khoy it was 21%. In Karaj, Zarghan (82.75%) and CMS19 (2.1%) were sensitive and resistant varieties, respectively, while in Khoy, followed by Sor (65.1%) and Eroflore (0.2%). In Karaj, early harvesting varieties suffered more damage (20.25% - 75.66%) than late harvesting varieties (2.1% - 82.75%). Morphometric measurements were made on head height from the ground surface, head diameter, sterile area to head diameter ratio, head angle, head shape and form of stem, and their correlation with bird damage were investigated. Pearson correlation was used for the first four factors and ANOVA and t-test for the two other factors. There was significant correlation (using Pearson correlation) between bird damage rate and the following factors: head height from ground surface, head diameter, sterile to head diameter ratio, and head angle (p <0.05). ANOVA and t-test showed significant differences between different head shapes and stem forms in sunflower varieties.