Applied Entomology and Phytopathology
Year:2014 | Volume:81 | Issue:2|Papers Count:18

Leopard moth, Zeuzera pyrina L. (Lep.: Cossidae), is a xylophagous pest which feeds on several host plants such as apple, pear, walnut and quince trees. Its activity results in withered branches and yield loss, finally causing death of trees. Detecting resistance mechanisms in resistant trees and deploying resistant varieties can be useful in managing leopard moth and conserving the environment from detrimental side effects of pesticides. In this research, resistance of 9 walnut and 17 apple varieties in orchard collection of Seedling and Seed Research Institute (Kamal-Shahr, Alborz province) was studied during 2009-2010 based on a completely randomized block design. For walnut varieties, 6 cohort trees for each variety were chosen and the number of larval entrance holes in six branches (four outside and two inside of canopy)/tree, were studied. For apple varieties, 3 cohort trees for each variety were chosen and the amount of larval feces at the base of each apple tree (based on the amount of larval fecal pellets which can be held in a tablespoon) and the number of larval entrance holes from base of the apple trees up to 1.5 m-height were studied. The maximum and minimum number of larval entrance holes in walnut varieties were observed on 'Z30' (6.16±0.45) and 'Z63' (1.25±0.49) respectively. Therefore, 'Z63' is recommended for further study regarding the detection of resistance mechanisms. In apple varieties, the maximum number of larval entrance holes (11.0±3.1) and maximum amount of larval feces (7.0±1.3 tablespoons) were recorded on ‘Richard Delicious’. ‘Northern spy’, ‘Jonathan’, ‘Prime Gold’ and ‘Red spur cooper’ varieties received the least damage (near zero) compared to the other varieties and they are recommended for further studies.

In this study pathogenicity and virulence of two Metarhizium anisopliae isolates (IRAN 437C and M14) were evaluated against egg (using dipping method), 2nd nymphal instar and summer generation adults (aestivation population) of sunn pest, E. integriceps (Hem., Scutelleridae) using direct spray technique. Different concentrations consisted 103, 104, 105, 106, 107 and 108 conidia/ml and experiment replicated 4 time. Effect of fungal suspensions of 106 and 108 conidia/ml in EC oil was also studied on sunn pest adults (aestivation population) using direct spraying method. Mortality in all of treatments was daily recorded. Results showed that isolate M14 reduced egg hatching by 40%. Estimated LC50 value for each isolates (IRAN 437C and M14) was 4.3´107 and 1.4´106 conidia/ml on adults and 4.8´104 and 2.3´103 conidia/ml on 2nd nymphal instar, respectively. Also, the calculated LT50 value using concentration of 108 conidia/ml for each isolates (IRAN 437C and M14) on adults were 29.64 and 11.9 days, and for nymphal stage were 3.23 and 2.22 days, respectively. The bioassay results showed that M14 isolate was more effective on both stages of the sunn pest. Although, nymphal stage was more susceptible compared to adult. In addition, EC oil (0.3 %) decreased LT50 of M. anisopliae to 54.45 percent compared with distilled water mixed with wetting agent (Tween 80). Adding oil carriers to a fungus suspension increased the pathogenicity.

Oviposition preference of Helicoverpa armigera on 10 canola (Brassica napus) cultivars (Talaye, Opera, Licord, Modena, SLM046, Hayula420, Zarfam, Okapi, RGS003 and Sarigol) was determined under laboratory and semi-field conditions. The first experiment was carried out under laboratory conditions using the leaves of 10 canola cultivars and the second one was done under semi-field conditions using the mesh cages. The results of the laboratory experiment of no-choice oviposition preference showed that the proportion of eggs laid on the plants to total oviposited eggs during total time period of the experiment was highest (0.760) for Talaye, and lowest (0.288) for Okapi. Moreover, the results of the laboratory experiment of choice oviposition preference indicated that the mean oviposition rate of H. armigera was the highest (112.37 eggs) on Opera and lowest (27.80 eggs) on RGS003. The results of choice oviposition preference under semi-field conditions showed that the oviposition of H. armigera was the highest (76.67 eggs) on Zarfam and the minimum number (14.42 eggs) was obtained on RGS003. Based on the results, RGS003, Okapi, Sarigol and Hayula420 were the less preferred cultivars for oviposition of H. armigera.

In order to study the efficacy of some applied herbicide used in grain corn an experiment was carried out in a Completely Randomized Block design with four replications and 18 treatments in Ahvaz, Varamin, Jiroft, and Isfahan. Treatments were the full-season hand weeded control, and post emergence (POE) applications of 2, 4-D plus MCPA at 1.5 lit.ha-1, Bromoxynil plus MCPA at 1.5 lit.ha-1, Nicosulfuran at 2 lit.ha-1, and Furamsulfuron at 2 lit.ha-1, pre-planting (PP) application of EPTC plus Dichloramide at 5 lit.ha-1 and pre-emegrcne (PE) application of Pendimethaline at 4.5 lit.ha-1, and combination application of EPTC plus Dichloramide (PE) at 5 lit.ha-1 plus 2,4-D puls MCPA (POE) at 1.5 lit.ha-1 or Bromoxynil+MCAP (POE) at 1.5 lit.ha-1, or Atrazine (PE) at 1 kg.ha-1, Alachlor at 5 lit.ha-1 (PE) plus 2, 4-D puls MCPA (POE) at 1.5 lit.ha-1 or Bromoxynil+MCAP (POE) at 1.5 lit.ha-1, or Atrazine (PE) at 1 kg.ha-1 and Acetachlor at 4.5 lit.ha-1 plus 2, 4-D puls MCPA (POE) at 1.5 lit.ha-1 or Bromoxynil+MCAP (POE) at 1.5 lit.ha-1, or Atrazine (PE) at 1 kg.ha-1. Results indicated that 2, 4-D plus MCPA and Bromoxynil plus MCPA were the good to excellent option to control broadleave weeds. Johnsongrass (Sorghum halepense (L.) Pers.) was controlled excellently by two herbicides "Nicosulfuron and Furansulfuron", but the efficacy of two mentioned new herbicides on barnyardgrass (Echinochloa crus galli (L.) Beauv.) were moderate to good and on common purslane (Portulaca oleracea L.) was moderate. Pendimethalian had the good to excellent effects on barnyardgrass and broadleave weeds, but it had no effect on johnsongrass and bermudagrass (Cynodon dactylon (L.) Pers.) Generally, the efficacy of 2, 4-D plus MCPA and Bromoxynil plus MCPA on broadleave weeds were better than Atrazine. Additioinly, Acethalchlor was better than Alachlor for controlling narrow leaves and broaleaves weeds. All treatments were safe for corn.

During the spring of 2011, several symptomatic hosta plants Hosta sieboldiana with mosaic, mottling and leaf deformation were observed in commercial hosta propagation greenhouses and gardens in Karaj and Tonekabon regions in Iran. A total of 17 symptomatic samples were collected and tested for the presence of Arabis mosaic virus-ArMV, Cucumber mosaic virus-CMV, Tomato spotted wilt virus-TSWV, Impatiens necrotic spot virus-INSV and Tomato ring spot virus-ToRSV by DAS-ELISA method. None of the tested samples had positive reaction with any of the antibodies. Some of symptomatic samples induced necrotic local lesions on Gomphrena globosa indicator plant in mechanical inoculations without inducing any symptom on other inoculated plants. Samples were tested for Hosta virus X (HVX) infection by reverse transcriptase polymerase chain reaction (RT-PCR) using specific primers designed for coat protein (CP) gene in this study and a DNA fragment with the expected size about 700 bp was amplified. CP sequences of Iranian HVX isolates showed 98.5 – 99.5 % nucleotide identity with 55 other non-Iranian HVX isolates. This is the first report of HVX occurrence in Iran and CP nucleotide sequence of five Iranian HVX isolates was determined.

The two spotted ladybird, Adalia bipunctata L., has been known as a polymorphic species for the coloration pattern of elytra and pronotum. In present investigation, A. bipunctata was collected on planted- (Pistacia vera L.) and wild- (Pistacia atlantica subsp. mutica F. & M.) pistachio trees in Kerman province, south of Iran during 2009 - 2010. The specimens were collected using a white beating tray, then were illustrated and examined using morphological characters based on available taxonomic keys. In total, 12 morphs of this species were identified. The prevalent melanic form was morph 2 (sexpustulata) and the most frequent non-melanic forms were morph 5 (typica) and morph 12 (revelierei).

The family Mymaridae (Hym.: Chalcidoidea) are cosmopolitan wasps, with about 103 valid genera and about 1,424 valid species worldwide, that are poorly known in Iran. In this study the genus Gonatocerus Nees (Hym.: Mymaridae) was studied in East- Azerbaijan province, located at northwestern Iran. Eight species are reviewed and identified from the studied area. The studied species in this research are as follow: G. (Cosmocomoidea) ater Förster, G. (Lymaenon) aureus Girault, G. (Lymaenon) litoralis (Haliday), G. (Gonatocerus) longicornis Nees ab Esenbeck, G. (Lymaenon) novickyi Soyka, G. (Cosmocomoidea) oxypygus Foerster, G. (Gonatocerus) pictus (Haliday) and G. (Lymaenon) thryides (Debauche). Of which, five species consisting: G. ater, G. aureus, G. novickyi, G. pictus and G. thryides are recorded for the first time from Iran.

Viral infection is one of the most important factor causing high yield losses of cucurbit crops in greenhouses and open fields grown condition. Mosaic and yellowing are the most prevalent symptoms in cucumber greenhouses in all over the world and Iran. Surveys were conducted from 2010 to 2011 in some cucumber greenhouses of Tehran and Alborz provinces and 219 leaf samples showing mosaic and yellowing symptoms were collected. The samples were tested for the presence of some prevalent cucurbit viruses by DAS-ELISA and RT-PCR. These results confirmed the presence of viral infection (~51%) in cucumber greenhouses and showed the infection of some samples to different viruses in different genus and families in all surveyed areas. Samples showing yellowing symptoms were also tested for the presence of viruses which involved or associated with yellowing symptom. DAS-ELISA and RT-PCR results confirmed the presence of CABYV, ZYMV, and CYSDV. This is the first report of CABYV and CYSDV from cucumber greenhouses in Iran. CABYV, CYSDV, and ZYMV were the most prevalent viruses in cucumber greenhouses. Mixed infections were found in ~19% of infected samples. Double infections were the most frequent of mixed infections and CABYV is the key role in double and triple infections. In order to CABYV strains identification (strain C and strain R), RT-PCR was carried out using specific primers. The samples were only infected with strain (C). Cucumber samples showing yellowing symptoms were also tested for whitefly-transmitted geminiviruses (WTGs) infection, using specific and degenerate primers in PCR. Despite of the presence of high population whiteflies and yellowing symptoms in many surveyed greenhouses, the samples were negative to WTGs infection.

One of the most significant and destructive grapevine diseases is Esca which is caused by several fungal species. Trunk disease causes stunted growth, reduced yield, and ultimately, vine death. For this reason, during the summer 2011, infected samples were collected from Bojnourd (North Khorasan province) vineyards. Infected trunk samples were acquired that they were showing white and brown rots, dark brown spots and also samples without apparent symptoms. The aims of this work were, firstly, to apply species –specific primers for detecting fungal agents associated with Esca disease of grapevine; and comparing this method to the classical ones, and secondly, to detect frequency of each pathogenic agent using molecular and classical methods. In molecular method, species-specific primers which designed based on ITs region of rDNA were used to detect fungal agents of the Esca disease. They yielded a single amplicon of 550 bp, 360bp and 415 bp for F. mediterranea, Pa. chlamydospora and Phaeoacremonium spp. respectively. Results showed that the maximum frequency of incidence was related to P. chamydospora and Phaeoacremonium spp was in second. The lowest incidence frequency rate was related to F. mediterranea which was observed only in sample with white rot symptoms. Primers defined here can be used in the nursery sanitation program to produce plant free of Esca disease.

Aflatoxins are highly toxic secondary metabolites produced by various Aspergillus species in food and feed. Nontoxigenic strains of A. flavus have been used for reducing aflatoxin of several crops. To determine the frequency of atoxigenic A. flavus population, samples were collected from different pistachio producing areas. A serial dilution method and AFPA medium was used to isolate Aspergillus section Flavi isolates. The ability of the isolates to produce aflatoxins was assayed using fluorescence detection (FD) around fungal colonies under UV 366 nm and color changing of colony after ammonia vapor (AV) exposure in the primary screening. First screening stage was validated by thin layer chromatography (TLC) after rice flour inoculation. The species of A. flavus were identified morphologically and molecularly based on species-specific primers. Overall, 524 isolates out of 681 isolates were identified as A. flavus. 53A. flavus isolates from nut and 10 isolates from soil did not produce any aflatoxins based on the methods used. Comparison of cultural and analytical methods showed FD methods overestimated the frequency of nontoxigenic strains while AV in combination with coconut agar medium produced similar results compare to TLC assays. The AV method can be used in the most laboratories as a practical, cheap, and rapid tool. Further efforts for assessment of competition potential of nontoxigenic strains versus toxigenic strains will be useful.

In order to identify Passalora and Ramularia species, Leaf spot symptoms from different plant hosts in Mazandaran province were collected and examined during the spring-autumn 2011-12. Passalora brandenburgeri (on Salix alba) and Ramularia variabilis (on Verbascum blattaria) are reported as the new records for Iran. Furthermore, Rosa hybrida and Rumex acetosa are new hosts for Passalora rosicola and Ramularia rubella in Iran respectively.

In a research to identify bee flies of Sanandaj region in years 2011 to 2012 was conducted few specimens of the genus Parageron Paramonov 1929 was collected by pan trapping at the location called traps in Khezr- E- Zendeh at 5 July 2012. Geographic coordinates of location was as: N 45o 56', E 35o 19' 1902 m. Specimens were identified by the key to palaearctic region, prepared by Evenhuis & Greathead, 1997, as Parageron. There has been no record of this genus in the catalog of family Bombyliidae from Iran so this finding represent the first record of Parageron from Iran. Parageron belonged to tribe Usiini and subfamily. Adults are small than 3 mm in lentgh. This genus includes 18 species in the world.Diagnostic characters of this species are as follow: flagellum with a sub apical sulcus containing a stylus, discal cell closed, oral margin much broader, eyes of males usually holoptic. Among the species of this genus P. inornata Engel, 1932 is recognized with the following characters: very long proboscis, 2-3 times of head width; thorax with thin and soft hair and dark lines, tibia orangish brown, remainder dark brown; legs with short bristles, abdomen with seven tergits; tapering toward last tergite; abdomen throughly covered with soft hair.

Mites of the genus Polyaspis Berlese, 1881 belong to the family Polyaspididae (Uropodina: Polyaspidoidea) and P. patavinus Berlese, 1881 is its type species which its morphological details represented by Athias (1975, 1976).These mites occur in litter, moss, and tree holes and feed on nematodes and small arthropods such as collembolans. Some diagnostic characters of the genus are: hypostomal setae h2 serrate, h3 smooth and movable digit of chelicera edentate. In the studies on uropodid mites in north area of Iran during about 10 years (2003-2013), several specimens of different stages of P. patavinus were collected mostly from forest litter in different area of Mazandaran, Guilan and Golestan Provinces. Also, some specimens of the species were collected in soil and litter of oak forests in Khoramabad County in spring of 2013. Previously, the genus has been reported from Iran by introducing an unidentified species, and this is the first record of a Polyaspis species from Iran.Some of the differential diagnostic characters of the species are as follows: A large suboval dorsal shield, a relatively narrow pygidial shield (ratio of length/width 3–4), and usually small and suboval marginal platelets bearing 1–3 setae on dorsal idiosoma; idiosomal setae with medium length or relatively short, mostly widened; genital shield suboval, densely covered with small polygonal reticulation, sternal setae v3 and v4 needle-like, on posterior area of shield; inguinal shields not attached medially behind genital shield.