Applied Entomology and Phytopathology
Year:2008 | Volume:76 | Issue:1 (85)|Papers Count:17

Saffron is one of the most important horticultural crops in Gonabad, Iran. There are many families that earn their livelihood with Saffron planting and it makes a considerable amount of income annually.Rhizoglyphus robini is the most harmful mite in saffron fields. This species causes corm rotting in soil which finally results in yield losses. To determine the effects of depth of planting and summer irrigation, the present study was conducted in Gonabad Agricultural and Natural Resources Station during 1999-2005 period. The study was laid out in factorial experiment based on Randomized Complete Block Design with four replications. The experiment consisted of three levels of planting depth and four levels of summer irrigation. Results showed that summer irrigation significantly increased mite population and yield 1osses. Depth of planting had not any significant influence on the mite population in spring, autumn and winter, while significant increases in mite population in the depth of 10 and 30 cm were observed in summer. Increasing depth of plantings resulted in the increasing of black spots on corms.The interaction of summer irrigation and depth of planting revealed that applying two irrigation maximize the mite population in all depths. However the minimum levels of mite population as well as black spots were observed with no irrigation. Higher the depth of deeper the corms planted higher the number of black spots found in plots with two irrigations. Higher mite population was observed in fields with higher planting record.

In order to evaluate gene effect, gene number and heritability for resistance to powdery mildew in barley, two cultivars were crossed with susceptible one. P1, P2, F1, F2 and F3 generation Hebe × Arigashar and Igri × Arigashar were planted in a randomized complete block design with three replications. At six different dates, disease severity was recorded for individual plant at three days intervals, starting before boot swollen. The area under the disease progress curve (AUDPC) was calculated and weighted analysis was used for the generation mean analysis. Resistance in the two adualt resistant genotype was dominant. The join scaling test indicated that the inheritance of powdery mildew was described by the additive-dominance components and epistasis, mainly additive × additive. Estimates of heritability for two cross was 74% and 84% and number of gene governing resistance ranged from 11-13 to 1 for two crossed mentioned above.

The Colorado potato beetle, Leptinotarsa decemlineata Say (Col.: Chrysomelidae), is the most harmful insect pest in potato fields. Precocene, a juvenile hormone inhibitor, has cytotoxic effects on insect’s corpora allata. The effects of precocene-І and precocene-IІ were tested on the 2nd larval instar of L. decemlineata by topical application in laboratory. The results showed that precocene-І and precocene-IІ increased larval mortality and developmental period, but had effect on pupal period. Both larval mortality and developmental period were directly correlated with precocene concentration. The most effective concentration of precocene was 50 mg/larva, which caused 95% (precocene-II) and 100% (precocene-I) mortality during larval period. Precocene did not influence number of larval instars and molting, but it led to early formation of pupal characteristic on larvae and formation of adultoids. Leptinotarsa decemlineata treated with precocene were also showed other severe morphological abnormalities, such as size reduction, body segmentation disturbance, strong deformation or complete reduction of wings and elytra, and persistance of old cuticle.

Relationship between temperature and developmental rate of different stages of Habrobracon hebetor Say (Hym.: Braconidae) were studied at 10 constant temperatures (16-38 oC). Development time for different stages of the parasitoid was obtained. Seven non-linear models describing the effect of temperatures on developmental rate were fitted to the observed data. Our statistical analysis indicated that the models, Logan 1 and Stinner were fitted well to all stages of Habrobracon hebetor (as indicated by r2 values). In this research, equations for above mentioned models referring to different developmental stages of the parasitoid have also been given.

Ground cherry (Physalis divaricata) is a summer-annual broadleaf species that has become a problematic weed in summer crops (common bean, soybean, sugarbeet, …) grown in the Lorestan province. Little is known about the effects of environmental factors on ground cherry seed germination. Studies were conducted at the Agricultural and Natural Resources Research Center of Lorestan to determine the effects of environmental factors on germination of Ground cherry. Ground cherry seeds germinated over a range of 14.8 to 45.9oC, with optimum germination (>70%) occurring at 24.3-36.4oC. Compared to control treatment (distilled water) ground cherry seed treatment with sulfuric acid by concentration of 20, 30, 40 and 50 percent caused significant increase of seed germination. In all level of potassium nitrate concentrations seed germination significantly increased compared to distilled water treatment. Increasing mucilage concentration above 30% dramatically decresed the Ground cherry seed germination. Mean seed germination of ground cherry in presence of mucilage at 30% concentration was 43%, while decreased to 10% and 2% as the mucilage concentration increased to 40 and 50 percent respectively. The time to 50% germination were prolonged as mucilage concentration increased.

The life table of Batrachedra amydraula Meyer (Lep.: Batrachedridae) was studied at 30±1oC, 60±5% RH and 24 hrs darkness, in the laboratory. The raw data was analyzed based on the age-stage two-sex life table, in order to take both sexes and the variable developmental rate among individuals and between sexes into consideration. Mean development times of immature stages were 51.91±1.61 and 53.3±2.3 for males and females, respectively. The intrinsic rate of increase (rm), the finite rate of increase (l), the net reproduction rate (R0), the growth reproduction rate (GRR) and the mean generation time (T) of B. amydraula were 0.039 d-1, 1.0398 d-1, 9.39 offspring, 59.68 offspring and 57.37 day respectively.

Flea beetles are serious insect pests of canola throughout Gorgan, Gilan, Zanjan, Khozestan and Markazi provinces. Attacking the plant at early stages results in considerable damages. The life cycle and seasonal population changes of the main species namely Phyllotreta corrugate, was investigated using sticky yellow traps and direct sampling methods in selected fields of Saveh region during 2002-2005. In addition, biological parameters were studied in laboratory conditions (23±2oC & 60±5% RH) simultaneously.The results revealed that the beetles overwintered as adult under the crop remains, appeared from early to late March in fields and started feeding on different cruciferous host plants. The adults completed feeding, mated, and oviposited individually or in small groups on the soil surface or one cm below it and in host-plant root area. In Saveh, new adults emerged on early June, when winter canola was under harvesting. These adults fed on newly emerged canola and crusiferous weeds for a while, then they aestivated until autumn, when fresh canola seedlings were available. The aestivated adults continued feeding on host plants until early December, when hibernation took place in the population due to climatic conditions. Based on the laboratory results, egg incubation, larval and pupal periods last 6-11, 18-28 and 8-15 days, respectively. This pest is monovoltine in Saveh region.

Adding fresh manure to cropland results in an increased weed population ensued from seeds present in the manure. Composting process can reduce weed seed viability. In an experiment seed viability of sixteen important weed species in forage fields were studied during composting process. Seeds enclosed within nylon mesh bags were buried into the two compost piles, at 0.5, 1 and 1.5 meters depths for 4 months in early summer in 2004. Two compost piles made from cow manure and one of them was covered by plastic sheets. Seed packets were removed monthly for 4 months to test seed viability.The results showed a dependence between weed seed viability lost in compost and composting high temperature. Compost piles tended to have higher temperatures at 0.5 meter (60-70oC) than 1 and 1.5m at first and second months, then the temperature decreased. This is probably because the pile was better aerated at the depth of 0.5m. Seed viability loss was different for each species. Some of species showed about 100% viability loss after one month. Weed seeds lost their viability at the 0.5m depth having higher temperature compared to deeper layers. In the covered compost pile, seed viability loss and temperature were lower than in uncovered compost pile. Almost all weed species were killed after being placed for 2 months at 0.5m depth of uncovered compost piles in summer. However, only viability of Cuscuta monogyna, Goldbachia laevigata, Chenopodium album and Amaranthus retroflexus were decreased after 3 months. Chemical test showed that water content reduced after one month composting at three different depths. pH values varied between 7 to 8. Carbon to nitrogen ratio was between 15-20 after three months of composting at three above-mentioned depths.

Head rot is one of the most important diseases of sunflower in the world. During recent years, the disease was observed in Golestan and Mazandaran, northern provinces of Iran. A survey was done during 1999 to 2000 and infected sunflower head samples with the disease symptoms were collected from various regions of Mazandaran. A total of 25 fungal isolates were obtained from the collected samples on the culture media. Based on the morphological and growth properties, all isolates were identified as Rhizopus oryzae. Record cultivar was inoculated by obtained isolates under green-house and field conditions. The symptoms were seen to be similar under the two different conditions. Rhizopus colonies reisolated from plants in the two experiments. In the experimental field conditions the yield losses were evaluted 100 to 44.11 percents at 4.2 to 4.5, and 6.43 to 3.35 percents at 5.1 to 5.3 flowering growth stages, respectively. In commercial fields, infection rates varied between 6 (Ran co., Behshahr) to 18 percents (Khorshid, Neka), and the yield losses were estimated from 0.64 (Kelt, Behshahr) to 1.78 percents (Khorshid, Neka), based on the infection occurrence time.

Tomato Bacterial canker disease, firstly reported in Iran from Urmieh in West Azarbaijan province in 1988. The disease causes lesion (canker), wilting and dryness of plants, leaf and fruit spots and whole plant decline. In this study, about 160 samples of infected plants were collected and sixty-four bacterial isolates were obtained from the infected tomato plants in Golestan and West Azarbaijan during 2004-2005. All isolates identified as Clavibacter michiganensis subsp. michiganensis based on morphological biochemical characters and pathogenecity test. Isolate Cmm (NCPPB382, Germany) was used as standard. Isolates showed considerable differences in using different sources of carbon and in their electrophoretic (SDS-PAGE) profiles of soluble cell proteins. Cluster analysis dendrograms obtained based on information derived from biochemical characters and protein electrophoresis, using software NTSYS-pc version 2.o2e, UPGMA method and Jaccard′s coefficient. Three groups (clusters) with %77 similarity based on biochemical data, 5 groups with %86 similarity based on SDS-PAGE results were realized. The results indicated high correlation and complementarirty. Resultes revealed I) heterogenesis between Iranian isolates and standard Cmm (NCPPB382), II) homogenesis between Golestan and West Azarbaijan isolates, and III) presence of different populations (strains) among the isolates selected from different areas. This is the first report of tomato bacterial disease in Golestan provice of Iran.

During spring and summer of 2007, whilst collecting Chalcidoidea (Hymenoptera) in the North-western parts of Iran, I swept several specimens of Sycophila mellea (Curtis, 1831) from herbaceous plants. These materials were collected from Azarbaijan-e-Sharghi Province, Marand, Peyam. This species is an addition to the Iranian list of the family Eurytomidae and the genus Sycophila. It was hitherto known to occur in the Palearctic and Nearctic regions. The specimens were deposited in Hayk Mirzayans Insects Museum (HMIM) in Tehran. Previously four species of Sycophila (S. biguttata, S. binotata, S. submutica and S. variegata), had been recorded from Iran. It was found in the collected materials from northern provinces of Iran and it seems that S. mellea is a common species which in Iran.Based on the literatures its chief host is Poaceae gall-maker eurytomids of the genus, Tetramesa. The combination of characters by which it can be distinguish from other species are given by Claridge (1959), Transactions of the Society for British Entomology 13: 149-168, Zerova (1995), Kiev, Ukraine, Naukova Dumka Publishers, and Lotfalizadeh & Gharali (2006), Zoology in the Middle East, 40: 77-84. The main distinctive characters are as follow: Pale species, black T-shaped marking in base of propodeum; submarginal band of forewing well developed but faded in discal area, marginal vein less than 3× as long as wide, stigmal vein longer than marginal vein, postmarginal vein wide partly fused with stigmal vein; pronotum about 1.5× as wide as long.

Hyphomycetous genus Gibellula Cavara accommodates species that are highly specialized and apparently are obligate parasites of spiders with worldwide distribution (Samson, R. A. & Evans, H. C., 1992; Mycologia, 84: 300-314). Their taxonomy has been discussed and identification key to eight accepted species and a variety is presented by (Samson & Evans, l. c.). Conidiogenesis is phialidic and their teleomorph belong to Torrubiella Boud. (Samson & Evans, l. c.). In a survey to Shastkola forest in the north of Iran, Golestan Province (Gorgan), a specimen on a dead spider on underside of Persian Ironwood (Parrotia persica (DC) CA. Mey) was collected and identified as G. leiopus (Vuill.) Mains. Macroscopic and Microscopic features of the fungus are given bellow. ...

In a survey carried out on mesostigmatid mites associated with Coleoptera in north eastern Iran in 2005-2007, Eviphis cultratellus (Berlese, 1910) reared and identified from Scarabaeus sacer L. Phoretic deuotonymphs, females and males extracted from the neck of the beetle hosts which were captured by light trap in Sarakhs, Feizabad and Taibad regions (Khorasan Razavi province). These mites feed on nematodes and some of them distribute by means of phoresy to access a new habitat. …

Based on the recent investigation, up to 12 species of hymenopterous parasitoids attack the pistachio twig borer moth, Kermania pistaciella Amsel (Lepidoptera: Tineidae: Hieroxestinae) in the pistachio plantations of Kerman province in southern part of Iran. Five species have already been reported (Achterberg and Mehrnejad, 2002, the braconid parasitoids of Kermania pistaciella Amsel in Iran, Zoologische Mededelingen Leiden), however the remaining 7 species are introduced as follow;1- Anastatus dlabolai Kalina (Hymenotera: Eupelmidae)2- Arachnophaga (Parasolindenia) matritensis Bolivar y Pieltain (Hymenotera: Eupelmidae)3- Chrysocharis laomedon (Walker) (Hymenotera: Eulophidae)4- Cyrtoptyx latipes (Rondani) (Hymenotera: Pteromalidae)5- Eupelmus (Macroneura) longicornis Kalina (Hymenotera: Eupelmidae)6- Eupelmus urozonus Dalman (Hymenotera: Eupelmidae)7- Pteromalus (Habrocytus) semotus (Walker) (Hymenotera: Pteromalidae). ...

In September 2006, I reported Chrysobothris solieri (Col.: Buprestidae) as new record from Iran. At that time two parasitic wasps, had been identified on C. solieri by Y. Maeek from Prague museum in Czech Republic.In this year, a few specimens of these parasitoid were studied which were determined as Varzobia tibialis Nikolskaya. This species is a new record from Iran.