Applied Entomology and Phytopathology
Year:2008 | Volume:75 | Issue:2 (84)|Papers Count:19

A survey was conducted to determine the distribution of Cauliflower mosaic virus (CaMV) in cauliflower (Brassica oleracea var. botrytis) fields. A total of 323 symptomatic cauliflower leaf samples were collected during different growing seasons from 32 fields in six provinces of Iran. These samples were tested by enzyme-linked immunosorbent assay (ELISA) using specific CaMV-polyclonal antibody. Serological diagnosis was confirmed by biological and polymerase chain reaction (PCR) tests. Based on ELISA, 292 cauliflower samples (90.4%) were infected with CaMV, ranging between 63.6-100% in the surveyed fields. Biological diversity of 21 CaMV isolates from various regions and with different symptom severity was evaluated based on their reactions on turnip (Brassica rapa), jimpson weed (Datura stramonium) and kohlrabi (B. oleracea var. gongylodes) plants. These isolates caused a variety of symptoms on turnip, including local lesions followed by vein clearing, mosaic, vein banding, rugosity and stunting. The severity of systemic symptoms observed varied depending on the isolate. In contrast, symptoms produced by the same isolates in Kohlrabi plants were restricted to older leaves and were much milder. Kohlrabi plants infected by all isolates tested eventually showed recovery and became asymptomatic. Eleven isolates induced local lesions on jimpson weed, and for two isolates, these symptoms were followed by systemic infections. All 21 isolates studied, were transmitted by green peach aphid (Myzus persicae). For molecular studies, ORF VI gene of nine selected CaMV isolates were amplified using specific primers. Comparison of sequences of the amplified fragments revealed a high identity (96.9-100%) among Iranian isolates studied. Comparison of these sequences with those available at GenBank indicated the highest identities of these isolates with D/H isolate from Hungary (96.1-96.7%). Phylogenetic studies showed clustering of Iranian isolates in a separate branch, together with the non-North American isolates. The Iranian isolates were also well differentiated from other exotic isolates using Hpy99I restriction enzyme.

The rice stem borer, Chilo suppressalis Walker overwinters as diapausing last instar larvae in which some carbohydrates were shown to be changed. To determine the presence of these compounds and their changes in diapause stage, mature overwintering larvae were collected from overwintering sites in rice fields during October 2004 to March 2005. Cryoprotectants and glycogen were measured by high-performance liquid chromatography (HPLC) and UV-Vis spectrophotometer respectively.Glycerol was identified as the major antifreeze compound and trehalose as the main sugar that both changed significantly during the different months. The lowest and highest content of glycerol was reported on October and January (1.21±0.18 and 15.53±3.7 mg/g of larval fresh weight respectively). In contrast of glycerol, trehalose showed the highest concentration on November (7.00±0.61 mg/g) and the lowest on January (2.79±0.57 mg/g); however, its content was nearly constant from November to late winter. Despite of negative correlation between glycerol and trehalose, this was not significant. Glycogen content was decreased as glycerol content was increased and there was negative and significant correlation between them (r=0.964; P<0.01) showing the interconversion of glycogen to glycerol during the overwintering period. It is concluded that glycerol may be more influential in cold hardiness of C. suppressalis in north parts of Iran and the insect’s diapause could be initiated on late November and terminated on February-March.

During a survey of Tetranychid mites in Northwest of Iran (2004-2006), four specimens from subfamily Bryobiinae and tribe Hystrichonichini were collected on Hazelnut (Corylus avellana L.) and Mediterranean willow (Salix aegyptiaca L.) in Fandoglo region (Ardabil province). They were identified as Tetranycopsis horridus (Canestrini and Fanzago). Tetranycopsis horridus and T. zambezianus are only species in the genus which appear to be injurious to economic plants. This is the first record of genus and species from Iran and Salix aegyptiaca identified as new host plant for T. horridus. The hazenut mite, T. horridus was recorded from hazelnut trees in Turkey (Ozman & Cobanoglu, 2001. Acta Horticulture, 556: 479-488.), Southeastern Europe, England, Russia and California (Jeppson et al., 1975. University of California Press, Berkeley, 614 pp.). It has also been reported on walnut, spruce, pine, yarrow and beans. Major characteristic features of the species are as follow: the claws and empodia are padlike with long tenent hairs. There are 4 pairs of propodosomal setae, anterior pair is very small. Dorsal setae are distinctly long and strong, set on prominent tubercles. There are 12 pairs of hysterosomal setae. The peritremes are free, anastomosing distally from lateral aspects of stylophore (Smith Meyer, 1987. Entomology Memoir No. 69. Department of Agriculture and Water Supply, Republic of South Africa, 174 pp.).

Entomogenous genus, Hirsutella Pat., is divided into two sections based on the presence or absence of synnemata. Some 35 mostly synnematous species are described (Minter, D. W. and B. L. Brady, Trans. Br. Mycol. Soc. 74(2): 271-282, 1980). Leaf hoppers collected from Shastkola forest in Gorgan (Golestan Province, see Fig. 1a) collected in September 2007 and those collected from Megophthalmus scabripennis (Acer leaf hopper) Gilan Province in Summer 2005 were examined. Specimens were identified H. versicolor Petch (Petch, T. 1931. Trans. Br. Mycol. Soc. 16: 227) following microscopic examination. Various specimens of this fungus were collected from leaf hoppers by Petch (Petch, l. c.). Despite all efforts the fungus could not be cultures on potato dextrose agar (PDA) or malt-extract agar (MA). A brief description together with a figure (Fig. 1) of this fungus is presented in this paper. Mycelium forms a pale yellow to greyish brown mat radiating from the leaf hopper to the leaf surface. Conidiophores reduced to sessile conidiogenous cells arising singly or sometimes 2-3 in verticillate or non-verticillate arrangements. Conidiogenous cells mostly monophialidic (with one slender, straight neck) or polyphialidic (with 2-3 such necks), hyaline, smooth 13-22 mm in length, swollen up to 3.2-4.2 mm wide near the base, tapering rapidly to one to three slender straight necks each about 0.5 mm wide. Conidia aseptate, hyaline, smooth, more or less falcate fusiform measuring 4.2-5.5×1.5-2 mm, formed solitary or in groups at the apex of the neck, embedded in a mucous sheath. At the apex of some phialides a globose conidium, about 4 mm (Fig. 1f) may be seen, that is described by Petch as a secondary spore. Perfect state of this fungus is described under Calonectria pruinosa Petch (Petch, l. c.) that was later combined in Torrubiella (Minter and Brady, l. c.).Measurements reported in this paper are slightly smaller than those reported by Petch and those specimens collected from Gilan Province had smaller dimensions compared with those collected from Golestan Province. Secondary spores reported by Petch were produced by all specimens examined (Fig. 1f, h). In specimens collected from Gilan Province thick hyphae resembling chlamydospores were seen (Fig. 1g). Slide preparation of the specimen collected from Gilan Province is preserved in the Fungus Collection of the Ministry of Jihad-e-Agriculture (IRAN 12669F).Another important entomogenous fungus, Lecanicillium muscarium (Petch) Zare & W. Gams, is isolated from the same specimen collected from Shaskola forest which is preserved in the culture collection of the Ministry of Jihad-e-Agriculture at the senior author's address under the accession code IRAN 1214C. This is a new record of L. muscarium from Iran on a leaf hopper. Both L. muscarium and H. versicolor are considered important natural biocontrol agents of this insect.

Red palm weevil (RPW), Rhynchophorus ferrugineus is one of the most important pests of different palms in Asia, North Africa and Europe. At present, it is an internal quarantine pest in Saravan region (Sistan & Balouchistan province, Iran). Also date palm fruit stalk borer (DPFSB), Oryctes elegans is one of important pests of palm in Iran and Asia.Several experiments on the possibility of mass trapping of two beetles, RPW and DPFSB with their pheromone traps, have been carried out in infested date palm groves during 2004-2005 in Saravan region. The results showed that the traps baited with separate dispensers of aggregation pheromone of two beetles in comparison with traps baited with pheromone mix (50:50 ratio) in one dispenser significantly attracted more O. elegans. But all bait types were equally attractive for R. ferrugineus. Also there was not any significant difference between the means of O. elegans catched by traps placed in different heights (ground surface, 1.5 and 4 m heights). The traps placed on the ground surface significantly attracted more R. ferrugineus in comparison with traps placed about 1.5 and 4 m above the ground surface. The effect of date palm core aging on the catching of two beetles was similar. Captures of traps that the date palm core replaced every week, were significantly greater than those with baits replaced every 2 or 3 weeks. So the number of captured insects decreases with time. These results indicated that pheromone traps with separate dispensers of pheromone of R. ferrugineus and O. elegans to place on the ground can be used for mass trapping of these two beetles.

The Platygastridae is a relatively small hymenopteran family with an estimated 1100 species. Although platygastrids are mainly parasitoids of whiteflies, mealybugs and cecidomyids, some species are egg parasitoids of beetles and hemipteran bugs. This family has been poorly represented in Iran, with only one species, Amitus spiniferus, known as a parasitoid of the whitefly Aleyrodes rosae from the central province of Isfahan (Ghahari and Hatami, 2000. Journal of Entomological Society of Iran, 20(1): 1-24).Here, the species Synopeas tarsa (Walker, 1835) is newly recorded from the city of Roudan in the Persian Gulf province of Hormozgan. The specimens were collected by A. Bagheri in a citrus orchard on May 4, 2004 along with parasitoid wasps of Citrus Leafminer (CLM). However the parasitic relationship of S. tarsa to CLM appears to be questionable.The host of S. tarsa remain unknown although gall midges in the family Cecidomyiidae are parasitized by three other species of the genus Synopeas (Vlug, 1985, Keys to species, redescriptions, synonymy. Tijdschrift voor Entomologie 127: 179-224.;.Kozlov, 1988. Keys to the Insects of the European Part of the USSR, Vol. III, Hymenoptera, part 2, Leiden, 1341pp.).

The almond seed wasp, Eurytoma amygdali Enderlein, 1907 (Hym.: Chalcidoidea, Eurytomidae) is one of important pests of almond trees in the Palearctic region (especially Mediterranean area). The first parasitoid of this economic pest was recorded in 1978 from Armenia and the second one was recently collected in Turkey. During a biological study (2004-2006) on seed wasps of stone fruit trees in Iran, apart from E. amygdali some chalcid wasps were reared from collected fruits of Amygdalus spp. (Rosaceae) from different parts of Iran. Within this collection two parasitoids species belonging to Pteromalidae and Eulophidae families (Hym.: Chalcidoidea) were determined. The identification was made by using Boucek & Rasplus, 1991. Institut National de la Recherche Agronomique, Paris, p. 95; Graham, 1969. Bulletin of the British Museum (Natural History) (Entomology) Supplement 16: p. 430 and Doganlar & Bolu, 2004. Zoology in the Middle East, 32: pp.76-78. for pteromalid species and Graham, 1987. Bulletin of the British Museum (Natural History) (Entomology), 55(1): pp. 270-272 for eulophid. The species were identified as Gugolzia bademia Doganlar and Aprostocetus bucculentus (Kostjukov). It is a new record of these species from Iran.ugolzia bademia Doganlar, 2004: Material examined: Chahar-Mahal & Bakhtiari, Shahr-e Kord, III. 2004, (S. Roshandel), 4♀(male) & 1♂  (female).Remarks: G. bademia belongs to Pteromalidae, Pteromalinae. It was described recently from Turkey and based on Doganlar & Bolu, 2004. Zoology in the Middle East, 32: p. 76, it is the second record of occurrence of this species.Aprostocetus bucculentus (Kostjukov, 1978):Material examined: Chahar-Mahal & Bakhtiari, Shahr-e-Kord, iii. 2004, (S. Roshandel), 5♀(male). Qazvin, 2001, (B. Gharali), 4♀ (male). Yazd, Mehriz, iii. 2004, (A. Jafari-Nadushan), 4♀ (male) & 3♂ (female).Remarks: This parasitoid belongs to Eulophidae and Tetrastichinae (Graham, 1987. Bulletin of the British Museum (Natural History) (Entomology), 55(1): pp. 270-272). Mentioned it in the subgenus, Aprostocetus. It is distributed in the Middle East including Armenia, Turkey and Palestine.

During the survey of ichneumonid fauna of Gilan province in 2006, one specimen of Cidaphus alarius (Gravenhorst, 1829) of the subfamily Mesochorinae was collected and identified. This is the first record of this subfamily, genus and species from Iran. The specimen is deposited at the Hayk Mirzayans Insect Museum (HMIM) in the Insect Taxonomy Research Department of Iranian Research Institute of Plant Protection.The subfamily Mesochorinae contains nearly 665 known species in the world, of which 163 species occur in the palaearctic region (Horstmann & Yu, 1999. Zeitschrift Arbeitsgemeinschaft österreichischen Entomologen, 50: 77-84).Diagnostic feature of Mesochorinae is as follows: Small to large; fore wings 6-29mm long. Clypeus usually not separated from face by groove, the apical margin evenly convex and without teeth; sternaulus of mesopleuron short or absent; fore wings with areolet large and usually rhombic (diamond-shaped) (Ceballos, 1925. Academia de Ciencias Exactas, Físicas y Naturales. Madrid. 31: 293pp; Constantineanu & Mustata, 1982. Fauna Republicii Socialiste Romania. 9(10): 1-105. in Romanian). Almost all species are koinobiont hyperparasitoids of ectoparasitic ichneumonid wasps and less frequently, of Tachinidae (Diptera) (Goulet & Huber, 1993. Research Branch Agriculture Canada Publication 1894/E. 667pp).Cidaphus alarius (Gravenhorst, 1829), 13mm. Fore wings 9.5 mm; hind wings 6 mm. Head black; anterior margin of compound eye concave; occipital carina complete. Tarsal claws pectinate. Metasomal segments compressed (Lee, 1991. Contributions of the American Entomological Institute. 26:1-48). The specimen attracting to the light and well known as hyperparasitoid of Ichneumon mixtus (Hym.: Ichneumonidae) (Schwenke, 1999. Spixiana Supplement. 26: 1-124.; Yu et al., 2005. CD/DVD. Taxapad, Vancouver, Canada).It is widely distributed in the Palearctic and Oriental regions (Lee, 1991. Contributions of the American Entomological Institute. 26:1-48; Yu et al., 2005. CD/DVD. Taxapad, Vancouver, Canada; Fitton, 1985. Entomologist's Gazette. 36: 293-297). Locality and date: Gilan, Loshan, Amarloo-Damash, 1750m. 12.VI.2006. Leg.: A. Masnadi-yazdinejad.

In a taxonomic study during 2005-2006 on Coccinellid beetles (Col.: Coccinellidae) in Fars province, Iran, a large number of species were collected and identified. Morphological characteristics and male genitalia were used for identification. Professor Fursch from Germany confirmed the identifications.Review of literature indicated that Tytthaspis sedecimpunctata (Linnaeus, 1758) is a new record for Iranian fauna. 6 male and 3 female specimens of this ladybird were collected on wheat plants in 12, May, 2005 from Khafr.This species was recorded from Austria, Belgium, Britain, Bulgaria, Croatia, Czech Republic, Estonia, Finland, Germany, Hungary, Ireland, Italia, Lithuania, Luxembourg, Poland, Romania, Russia, Slovakia, Sweden, Switzerland, Netherlands and North Africa (Fauna Europaea Web Service, 2004; Available online at http://www.faunaeur.org).Tytthaspis Crotch 1874 and Micraspis Dejean, 1836 are synonymies and belong to Coccinellinae Latreille, 1807.T. sedecimpunctata (Linnaeus, 1758) is a small ladybird, 2-3 mm long, yellow in color with 16 black spots on elytra known as Sixteen-spot Ladybird.

Melanophila picta is one of the most important pests of poplar trees in Karaj. From 1993 to 1995, biology and natural enemies of the pest were studied with weekly samplings of poplar trees, and rearing of insects on poplar trees and cutting stems of poplar under controlled conditions in Alborz Research Complex, Karaj. The adults appeared on poplar trees from early May to the end of June. Peak of adults population was observed in early June. After mating the females were frequentely laied their eggs in bark crevices or around lateral buds of poplar trees. The average number of eggs per female was 108.08±56.30, and the average ovipositions and the incubation period of eggs were 15.29±7.02 and 7.14±1.21 days, respectively. Following the hatching of the eggs, the larvae feed superficially inside the bark, inner phloem and the cambial layer just beneath the bark. They bore the sapwood and construct larval tunnels with the lengths up to 10 centimeters. M. picta overwintere as last instars larvae inside sapwood. Overwintering larvae re-start their activity in early spring of the following year. The first pre-pupa and pupa were observed in pupal chambers from mid April and mid or late April, respectively. The average pupal period is about 15.18±6 days in Karaj area and the insect had 1 generation per year. Sex ratio (♀(male):♂(female)) was observed 1.14:1. During this study, 4 species of parasitoid wasps belonging to families Encyrtidae, Braconidae, Ichneumonidae and Chalcididae, as well as 1 species of predatory ant (Lasius alinus) were reared on the M. picta Pall. larval parasitization by Braconidae and Ichneumonidae families was estimated 4.21 and 17.72 percent, respectively in 1995.

In order to study the possibility of resistance in Amaranthus retroflexus L. and Amaranthus blitoides S.Wats biotypes to Chloridazon, Desmedipham and mixture of these two herbicides in sugar beet fields of West Azarbayejan, Isfahan, Fars, Khorasan and Khoozestan provinces, two experiments were conducted at greenhouse of Weed Research Department of Iranian Research Institute of Plant Protection during 2003 and 2004. The experimental design was completely randomized design using a factorial approach (27 biotypes of pigweed by 3 herbicides in greenhouse experiments and 6 biotypes of pigweed by one herbicide in bioassay trial) with 4 replications. The seeds that were suspected to be resistant at the recommended rates of herbicides were collected from the fields of these provinces and the susceptible seeds that had never been treated with herbicides were used in these experiments. In the greenhouse experiment for screening the suspected and susceptible biotypes, the percent dry weight and visual control were compared with untreated control biotypes. Any biotype was considered to be possibly resistant if the mean dry weight of the survivors was at least 50% of the untreated control plants. Six biotypes with inadequate control from greenhouse trial were selected and treated with six doses (0, 0.5, 1, 1.5, 2, 2.5, 3 g/l) of Chloridazon in bioassay test using petri-dish. For assessment of biotypes the root length were measured. The greenhouse experiments indicated that none of the biotypes were resistant to these herbicides, but the biotypes showed different responses to the herbicides and the biotypes such as FR(Am)1 and MR(Am.bl)5 were not completely controlled by Chloridazon. The biotypes such as ER(Am)2 and MR(Am.re)1 were less controlled by Desmedipham and also biotypes such as ER(Am)1, ER(Am)3 and MR(Am.bl)6 were inadequately controlled by mixture of two herbicides. Although the biotypes did not show resistance to the herbicides, the repeated use of PS II herbicides can lead to the emergence of resistant weed population. Results in bioassay test showed that with increasing dose of Chloridazon, the percent root length of all biotypes was decreased and herbicide resistance did not observe.

Viral diseases and their vector insects have a great concern in seed potato production. Systemic insecticides by killing the vectors reduce the incidence of the diseases especially in early growing stages of potato plants. In this study, the ability of seed tuber treatment with two neo-nicotinoid root absorbing systemic insecticides, thiamethoxam and imidacloprid, were evaluated to control the insect vectors and viral diseases under field conditions with natural occurrence of vector populations. The tests were conducted using a split plot RCBD design with 3 insecticides (thiamethoxam, imidacloprid and thiodicarb) as sub-treatment and 2 potato cultivars (Agria and Marfona) as main treatment in 4 replicates. The trials were performed in two locations, Bahar (Hamadan) and Firozkoh (Tehran), in 2001 and 2002. Each insecticide treatment consisted of seed tuber treatment at planting and second treatment at hilling. In seed tuber treatment, thiamethoaxam (Cruiser 350FS), imidacloprid (Gaucho 70WS) and thiodicarb (Larvin DF80) were used at 20mL, 28.5 gr and 37.5 gr ratio for 100 Kg seed tuber, respectively. In soil application at hilling stage of potatoes, thiamethoaxam (Actara 25WG), imidacloprid (Confidor 350SC) and thiodicarb (Larvin DF80) were used at 0.14 gr, 0.14 ml and 0.05 gr ratio, respectively, for each one meter of potato rows in field. Vector populations in 3 groups including aphids, leafhoppers and thrips were evaluated. Incidence of Alfalfa mosaic virus (AlMV), Potato leaf roll virus (PLRV), Potato virus M (PVM), Potato virus S (PVS) and Potato virus Y (PVY) in the plots was detected by double antibody sandwich-enzyme-linked immunosorbent assay (DAS-ELISA). Also, Tomato spotted wilt virus (TSWV) was detected by reverse transcription followed by polymerase chain reaction (RT-PCR) using specific primers as previously described. The data of early and late season tests were statistically analyzed. The results indicated that in early and late season, seed treatment with thiamethoxam and imidacloprid reduced significantly aphid and leafhopper numbers up to 3 fold relative to no treated controls. Thrips population was reduced up to 2 times in early season and 3 times in late season. Also, the incidence of AlMV, PVM, PVS, and PVY reduced up to half in early season and one third in late season in relative to non treated controls. Incidences of PLRV and TSWV in both early and late season were one fourth and one third of no treated controls, respectively. Thiodicarb treatments had not acceptable control on vector and disease incidence. Our results showed that seed potato tuber treatment at planting with thiamethoxam (Cruiser 350FS) or imidacloprid (Gaucho 70WS) at a ratio of 20 gr and 28.5 gr. per 100 kg of tubers, respectively, with a mid season soil application of thiamethoxam (Actara 25WG) or imidacloprid (Confidor 350SC) at a ratio of 0.03 gr and 0.14ml per one meter of plant rows, would reduce the vectors populations and viral disease incidence in potato fields. The Advantages of application of systemic root absorbing pesticids in vector and virus control in seed potato fields was discused.

Studies were conducted to investigate the antixenotic resistance of 15 Iranian rice cultivars to Sitophilus oryzae (L.) under laboratory conditions at 28 ±1oC, 70 ± 5% R.H. and 0:24 (L:D). The experiments were carried out under randomized complete block design in 2004. A mixture of 75 male/female of rice weevil was introduced in each of 4 replications for a period of 24h and 48h. In a free choice test, the orientation and colonization responses of the weevil were evaluated. There was not significant interaction between cultivar effects and time intervals, so a period of 24h was enough for adults settlement on their preferred cultivars. Twelve pairs of male and female weevils (1-8 days old) were released in each of 5 replications to estimate the oviposition response for choice test followed by egg-plug counts after 72h release. In both experiments, S. oryzae exhibited the lowest preference and oviposition on Kadus cultivar, therefore, Kadus could be considered as a potential resistant cultivar and to be investigated in further complementary experiments.

In two field experiments the effects of cover crop monoculture and polyculture on weed control of tomato (Lycopersicum esculentum) was investigated in Varamin Research Station during 2003-2005. Each experiment consisted a split plot design in a complete randomized block arrangement with three replications. supplemental weed control with 2 levels (weeding and weedy) were allocated as main plot and mixture of rye (Secale cereale) and hairy vetch (Vicia villosa) at 5 levels (100% rye + 0% hairy vetch, 25% rye + 75% hairy vetch, 17.5% rye + 82.5% hairy vetch, 10% rye + 90% hairy vetch and 100% hairy vetch + 0% rye) were placed as subplots. Results showed that biomass of rye and cover crop mixtures were higher than hairy vetch monoculture. Cover crop mixtures reduced weed density and biomass as compared to vetch monoculture in the first year. However, in the second year weed control of all cover crop treated plots was similar. Fruit yield in both years were similar in hairy vetch and rye monoculture and all mixtures but was lower in the rye monoculture in the first year. Tomato grown in the cover crops without weeding yielded lower than the corresponding weed free treatments. Cover crops affected fruit and plant weight and number of fruit on plant.