Iranian Journal of Plant Protection Science
Year:2010 | Volume:41 | Issue:2|Papers Count:20

Sphecidae is a large and important family of Hymenoptera. All members of this family are presocial predators of other arthropods and play a role in the control of pest complex. In this study, sphecids were collected from East Azerbaijan province using sweep net, Malaise traps and yellow pan traps. Twenty species of the family Sphecidae (Hymenoptera), belonging to subfamilies Pemphredoninae, Astatinae, Larrinae, Nyssoninae and Philanthinae, were collected from the province. The two species Psenulus pallipes Panzer and Cerceris rybyensis (Linnaeus) along with the genus Diploplectron Fox are new records for Iranian fauna. An identification key has been given for the genera and species, illustrated by figures and photographs.

Pathogenic diversity in Didymella rabiei in Ilam and Kermanshah provinces was assessed with the objective of finding out about the existence of pathotypes. One hundred isolates from different farms of chickpea growing regions in these provinces were collected in 2007. Isolates were arranged into ten different groups based upon their sampling regions. One isolate was chosen from anyone of the ten groups as the representative isolate one. Pathogenecity of the selected isolates was conducted on a set of seven chickpea differential hosts in glasshouse conditions. Reaction types of the ten isolates were studied one month past inoculation and on the basis of a 9 point scale. Based on disease reaction on differential hosts in accordance with disease reaction pattern on differential lines in ICARDA, three pathotypes were identified. The pathotypes included: pathotype 1 from Mehran, Ivan in Ilam province, Gilanegharb, Ghasrshirin, Sararoud and Sahneh in Kermanshah province; pathotype 3 from only Darahshahr in Ilam province, and finally pathotype 6 from Abdanan, Shirvan Chardavol in Ilam province and from Sarpolezahab in the province of Kermanshah.

Faunistic study of cryptostigmatic mites (Acari: Oribatida) in Rasht township was conducted during 2008-2009. Mites were extracted using Berlese funnel from soil samples and cleared in lactophenol. Cleared mites were mounted (in Hoyer’s medium) on microscopic slides. In total, 15 species, 15 genera and 13 families of oribatid mites (Acari: Oribatida) were collected and identified. Among the identified specimens, 12 species, 11 genera and 8 families are for the first time records from Guilan province while one species, two genera (with unknown species) and two families are the first record from Iran. The following list consists of the identified genera and species with the new records for Guilan province marked by one asterisk while the new records for Iran marked by two asterisks. Hypochthonius luteus* Oudemans, 1917, H. rufulus Koch, 1936 (Hypochthoniidae); Mesoplophora (Mesoplophora) michaeliana* Berlese, 1904 (Mesoplophoridae*); Sphaerochthonius splendidus* (Berlese, 1904) (Sphaerochthoniidae*); Phthiracarus incredibilis* Niedbala, 1983 (Phthiracaridae); Steganacarus (Steganacarus) spinosus* (Sellnick, 1920), S. (Tropacarus) brevipilus* (Berlese, 1923), Atropacarus (Atropacarus) ochraceus* (Niedbala, 1983) (Steganacaridae*); Rhysotritia ardua* (Koch, 1841) (Euphthiracaridae*); Lohmannia turcmenica* Bulanova-Zachvatkina, 1960, Papillacarus aciculatus* (Berlese, 1905) (Lohmanniidae*); Perlohmannia dissimilis (Hewitt, 1908) (Perlohmannidae); Epilohmannia cylindrica cylindrica* (Berlese, 1904) (Epilohmannidae*); Nothrus biciliatus* Koch, 1841 (Nothridae*); Heminothrus (Platynothrus) grandjeani** (Sitnikova, 1975) (Camisiidae*); Idiodamaeus** sp. (Idiodamaeidae**); Ctenobelba** sp. (Ctenobelbidae**).

The Sigatoka disease complex of banana involves three related ascomycetous fungi viz., Mycosphaerella fijiensis, M. musicola, and M. eumusae. Due to rather similar symptoms on banana, similar teleomorph morphology and problems associated with growth and sporulation in culture, species identification based on classical methods is troublesome. The exact distribution of these three species and their disease epidemiology remain unclear. Furthermore, M. fijiensis and M. eumusae have not been reported from many banana producing countries, so as to be considered as quarantine organisms. Rapid and accurate detection of these three species is essential to adopt and apply proper disease management strategy. In the present study, species-specific primer sets were developed as based on sequence data of actin gene. Species-specific primer combinations were designed with expected amplicon sizes of 500 bp from M. fijiensis, 200 bp from M. musicola, and 630 bp for M. eumusae. Accuracy and efficacy of each of species-primer sets were tested and verified on DNA extracted from pure cultures as well as DNA from naturally infected banana leaves. The sensitivity of the primer sets enabled reliable detection of M. fijiensis DNA as low as 100 pg, whereas for M. musicola and M. eumusae a higher sensitivity was achieved of 1 pg and 10 pg genomic DNA, respectively.

Ourmia melon virus (OuMV) is the causal agent of mosaic disease on melon in West-Azerbaijan province and probably in some other parts of Iran. Symptomatic and non-symptomatic samples of cultivated and non-cultivated hosts were collected from most cucurbit-planting parts of the province and surveyed using common serological methods namely: Indirect-ELISA, Direct-ELISA and Lateral flow. Some squash, cucumber, cantaloupe and melon samples were collected from the Experimental Fields of the College of Agriculture Karaj, while several samples were obtained from Shiraz regions to be tested upon. Distribution of OuMV during 2006-2008 and in western Azerbaijan province was surveyed whith squash, cucumber, melon, watermelon, cantaloupe, eggplant, tomato, carrot and bean detected as cultivated hosts while black binweed (Convolvulus sp.), red root pigweed (Amaranhtus retroflexus L.) and prickly lettuce (Lactuca scariola L.) as non-cultivated hosts. The virus was transmitted from the infected plants to healthy ones just by contact while other methods of transmission failed. Local varieties of cucumber and squash were observed to be more sensitive to OuMV than the commercial ones, as found out through resistance/tolerance assay. Occurance of the virus in other provinces of Iran showed its prevalence in other parts of the country too.

Biology of amaranth stem-boring weevil, Hypolixus pica (Fabricius) on red root pigweed, Amaranthus retroflexus L. was investigated under natural conditions in a citrus orchard in Dezful. Each red root pigweed was covered by a wooden cage of 50×50×100cm dimentions screened by muslin. Three to four adult females and males were introduced into each cage. After 3-4 days past the weevils were removed and the biology of the insect in its immature stages investigated. The insect bore three generations. Under natural conditions the duration of egg and pupa of the second generation were 3 and 8.86±0.84 days and the duration of egg and pupa of the third generation 3.55±0.49 and 10.33±0.47 days, respectively. The developmental time of the second and third generations lasted 44.68±4.01 and 50.88±4.67 days, respectively. The weevil was found to overwinter as either its last larval instar (fourth) or as adults. Females laid eggs in stems covering them by a black secretion. The larvae moved downwards, tunneling the stem. The adult stage made a hole above the gall and left the stem. The adult stage insect damaged the leaves and the seeds of A. retroflexus as well.

Common wheat, Triticum aestivum L. is of the greatest importance among the few crop plants that are grown extensively and for food in Iran. Among the reported wheat's pests, greenbug Schizaphis graminum (Rondani) causes severe damage to the crop. Because of the adaptation of the aphid to different wheat varieties being varied, this study was designed to focus on the effect of some common wheat varieties in Karaj region, namely: Pishtaz, Shiraz, Chamran, Mahdavi and Marvdasht on the biological parameters pertaining to the greenbug. The experiments were carried out in incubator and under controlled conditions of 22±1oC, 70±10% humidity and 16:8 photoperiodism. The results indicated the longest nympahl period on Marvdasht (7.39 days) and the shortest on Shiraz variety (6.36 days). The highest number of nymphs was produced on Shiraz (46.42) and the lowest on Mahdavi (35.72). The parameters rm, R0, l, T, and DT in relation to the aphid were also assessed and statistically compared on each wheat variety. A comparison of rm as the most important parameter indicated that the highest rm was obtained for Shiraz (0.31) while the lowest for Mahdavi and Marvdasht variety (0.28). The fertility life table parameters revealed that Shiraz was the most sensitive to greenbug in comparison with the other varieties. For the calculated parameters, pseudo-replicates were produced through jackknife and bootstrap re-sampling methods, and the results from the two methods were compared.

A computer software was designed to facilitate identification of nematode species. The first section of the computer program was prepared to identify the species of the genus Criconemoides. NEMIDSOFT can be easily installed on personal computers with a minimal requirements. The software can be edited by users and developed and generalized to other genera of the nematodes. By having the morphological characteristics and morphometrical data entered in the search section of the software, some of already identified and closely related species in the database are introduced to the user as the most similar species to the understudied populations. The user, based on a description of the introduced species available in the database, is led to select one of the species that is closest to the population. NEMIDSOFT is a very user-friendly tool and is the first designed software for computer identification of nematodes in Iran.

Turnip mosaic virus (TuMV), Cauliflower mosaic virus (CaMV) and Beet western yellow virus (BWYV) are considered as the most important viruses of canola, worldwide. In order to determine the distribution of these viruses in Golestan province, samples from three important canola growing areas of the province were collected during 2008 and 2009. The randomly collected samples were tested for the presence of TuMV, CaMV and BWYV through DAS-ELISA. The results revealed that canola field infection levels in 2008 with TuMV, CaMV and BWYV were at 4.5%, 2.5% and 6%, respectively. Canola field infection in 2009 with TuMV, CaMV and BWYV was at the levels of 8.33%, 1.66% and 6.33%, respectively. Data analysis showed that virus factor was significant for 2008 whereas region was the factor significant for year 2009. Furthermore, BWYV infection was confirmed through RT-PCR. It is to be mentioned that this is the first report of TuMV, CaMV and BWYV on canola in Golestan province.

The black bean aphid, Aphis fabae Scopoli, is a major pest of broad bean, Vicia faba L. and sugar beet, Beta vulgaris L., The most abundant parasitoid of A. fabae in agroecosystems is Lysiphlebus fabarum (Marshall), a multivoltine species with mainly thelytokous reproduction in central Europe. Since L. fabarum females mimic ants to obtain honeydew directly from aphids it was reasoned that a female's hunger level could influence her proportional time allocation to various behaviors associated with aphid exploitation. To test this, L. fabarum females were released individually onto bean leaf disks infested with A. fabae and continuous observations made. The females’ proportional time allocations were then recorded. Furthermore, instances of aphid defensive behaviors including kicking, raising and swiveling the body, releasing the plant and escaping from attack, as well as attempts to smear the attacker with cornicle secretions were numerically assessed. Hungry females spent 3.6 times longer in host patches (leaf disks with 15 second-third instar of A. fabae) than did females fed diluted citrus honey prior to testing, but there were no differences observed among number of aphids parasitized. All the assessed measured distinct behaviors were higher for unfed females than for fed ones. Because of the large effect of treatment on patch residence time, the incidence or duration of various behaviors was expressed as a fraction of patch residence time and then re-analyzed. Hungry females spent proportionally more of their time resting and antennating aphids with proportionally less time spent in searching, abdominal bending and probing aphids. A significantly smaller proportion of aphids kicked and escaped from attack following encounters with hungry females than when encountered with satedly fed females.

The snail Caucasotachea lencoranea Mousson is a pest of citrus in the north provinces of Iran. In order to adopt a better control of the pest and develop optimal management strategies, an understanding of the digestive enzymes’ function is inevitable. Snails were collected from some citrus orchards in the northern provinces of the country and digestive carbohydrases including a-glucosidase, b-glucosidase and a-amylase were investigated. For preparation of the enzyme extract from the digestive system, snails were dissected and the whole digestive glands removed. Results indicated that a-, b- glucosidase and a-amylase were present in the digestive gland of the pest. Optimum pH for a- glucosidase activity was obtained in the range of 4-5 and for b-glucosidase at 5-6. Optimum temperatures for a-glucosidase and b– glucosidase activity were recorded as 35oC and 40oC respectively. Optimum pH for a-amylase activity was 2 while the optimum temperature recorded as 40oC. Km and Vmax values of 9.84 mM and 0.11 mM/min were obtained for a-glucosidase respectively. The values of Km and Vmax for b-glucosidase were 10.48 mM and 0.0421mM/min respectively.

Some types of Faba bean suspected of root pathogens in Lorestan provincec, Iran were sampled during years 2007 to 2008. After some pathogenicity tests, 121 samples which suffered from root fungus disease and from chromista were totally isolated. The abundance of fungi, Fusarium solani, which caused the faba bean root rot was more than that of the other separated types and as well as the farming damages throughout the province looked more. The next respective abundant species were: Fusarium oxysporum, Rhizoctonia solani, Macrophomina phaseolina, and Pythium sp. A Pythium and Macrophomina, were first report for these species from Iran. In addition to these referred to agents, 57 bacterial strains from the above mentioned fields and from the rhizosphere of faba bean were also isolated. They were tested for antibiosis quality as well as inhibiting strains that were selected through formation of inhibiting halo in the presence of pathogens. Strains were identified by the aid of biochemical, morphological, and physiological attributes. The strains of, R10 and R14 were recognized as the genus Rhizobium and the strains P42, P34, P38 and P8, as belonging to the genus of Pseudomonas. These strains were applied in two modes of: 1) soil treatment, 2) seeds being soaked against pathogenic agents. The results revealed that when the bacterial suspension carrying Rhizoctonia solani, Macrophomina phaseolina, and Fusarium solani was added to the soil, the dry weight of the plant would be 1, 0.36, and 0.37 g respectively. When the seeds were soaked, the plants polluted with, Fusarium solani, Macrophomina phaseolina, and Rhizoctonia solani had the dry weights of, 0.34, 0.41, and 0.43 g. These results revealed that the growing factors of the plants which had an influence on the two isolations (when the soil was polluted) were increased, but these factors (in the case of two isolations of Marophomina phaseolina), were intensified only when the seeds soaked. All in all the results indicated that the strains of P8, P34, P38, and P42 were significantly the most effective in increasing the dry weights of the plants.

The developmental period, prey consumption of different nymph instars, survival, reproduction and longevity of Orius albidipennis were studied on three different diets including the two-spotted spider mite, Tetranychus urticae plus corn pollen; two-spotted spider mite; and eggs of Sitotroga cerealella plus corn pollen under laboratory conditions. Leaves of Pelargonium hortom served as oviposition substrate as well as moisture source. The results showed that developmental periods from egg to adult were significantly higher on eggs of grain moth plus corn pollen than on T.urticae and T. urticae plus corn pollen. The female longevity was significantly higher on grain moth eggs plus corn pollen than on T. urticae plus corn pollen and on T. urticae. There were no significant differences among the three different diets as male longevity was concerned. The survival rates on T.urticae plus corn pollen and on T.urticae were significantly higher than on the eggs of grain moth plus corn pollen. The oviposition period and fecundity rate on grain moth eggs plus corn pollen were significantly higher than on T. urticae plus corn pollen and on T. urticae. Daily egg-laying of O. albidipennis feeding on T. urticae plus corn pollen and on T. urticae were significantly higher than on grain moth eggs plus corn pollen. The sex ratio (the female to whole population ratio) was higher on grain moth eggs plus corn pollen than on the other two diets. The kind of diets didn’t have any effect on premating period, preoviposition period, embryonic development and percent of egg hatching. Results indicated that the bug O. albidipennis can act as the biological control agent against two spotted spider mite and secondly that the eggs of grain moth plus corn pollen constitute a suitable feed for rearing of this predator.

An identification of the environmental factors regulating the biosynthesis of antibiotics by fluorescent pseudomonads is an essential step toward improving the ability of these bacteria to control plant pathogens. Investigation of nine fluorescent pseudomonads, utilized in growth suppression of Rhizoctonia solani, the causal agent of root rot and damping-off of bean plants, by the method of HPLC showed that the three isolates Pf-100, Pf-101 and Pf-68 were able to produce pyoluteorin (Plt), 2,4-diacetylphloroglucinol (DAPG) and monoacetylphloroglucinol (MAPG). Study of the influence of different liquid cultures and time on DAPG production revealed that in KB only Pf-100 and in KBG as well as in YM all the three isolates produced DAPG with the antibiotic concentration being different depending on time past. GCM medium stimulated DAPG production in Pf-101 and Pf-68 within 24 h. MAPG production on KBG was detected in Pf-68 and Pf-101, while on YM all the three isolates produced MAPG with its production decreasing with the passage of time. KB stimulated Plt production by the three isolates and the antibiotic concentration reached its maximum levels at 24, 72 and 96 h for Pf-100, Pf-101 and Pf-68, respectively. Plt production was stimulated in KBG growth medium in all the three isolates but its concentration was lower than that in KB.

Wolbachia is an intracellular endosymbiont, which can induce thelytokous parthenogenesis in Trichogramma egg parasitoids with the infected females producing daughters without any mating. With regard to the usual transfer of Wolbachia which is vertical from the mother to her offspring through the cytoplasm of eggs, this manipulation of host’s reproduction can enhance its transmission to future generations. In this study, the intra- and interspecific transfer of this bacterium among Trichogramma wasps were investigated using one Iranian infected line of Trichogramma brassicae Bezd. (B 11W+) as donor and two Dutch uninfected lines of T. brassicae and Trichogramma evanescens West. (Y 175 and GD 011) as recipients. In both cases, horizontal transfer was observed when infected and uninfected parasitoid’s larvae shared the same host egg, Mamestra brassicae (L.). The F1 females from recipient lines were tested for the presence of Wolbachia and to determine their origin through PCR using wsp primers, specific primer of the ITS-2 region as well as TTG 49 microsatellite primer, respectively. On the whole, intraspecific horizontal and subsequent vertical transmissions (%78.8 and %38.5) occurred with significantly more success than interspecific transfer. Because of the advantages of unisexual wasps in biological control programs, the results obtained may be found as very useful in practival applications.

The entomopathogenic fungus, Beauveria bassiana (Bals.) Vuill., is one of the facultative insect pathogens with a significant host range and host specificity. Conidial survival may be affected by either environmental factors or by bio-pesticides and chemical products used to protect crop plants. In this research, compatibility of the above mentioned fungus was studied with some traditional insecticides namely: imidaclopride, flufenoxuron, amitraz, and as well with neem (Azadirachta indica A. juss (Meliaceae), Stinking assa (Ferula assa-foetida L. (Apiaceae)), Oleander (Nerium oleander (Apocynaceae)) and NeemAzal-T/S. Effect of pesticides and plant extracts on conidial germination and on vegetative growth of the fungus were studied. The formulations of pesticides and plant extracts were tested in three sets of concentrations (mean concentration-MC, half MC and twice the MC). The results indicated that flufenoxuron, neem, NeemAzal-T/S are not compatible with B. bassiana causing either complete or strong inhibition in its development. The compatible formulations with B. bassiana (isolate DEBI008) were on the other hand imidacloprid, oleander and stinking assa. These later formulations could be employed simultaneously with the entomopathogenic fungus in integrated pest management.

Carob moth, Ectomyelois ceratoniae Zeller (Lep.: Pyralidae) is considered as the most important pest of pomegranate in Iran causing serious damages up to 80% at pre and post harvesting stages. In this study larval parasitoids of carob moth were collected from three regions of production sites of pomegrante namely: Varamin, Qom, and Saveh during 2007. Eight species were collected from Varamin, 7 species from Qom and 4 collected from Saveh. The braconid, Apanteles myeloenta Wilkinson was the most prevalent species among the collected parasitoids which could be found in all the sites of study. The emergence peak of parasitoids occurred at the end of the cropping season (September). Parasitism started in Varamin from Aug., being continued until Oct. It prevailed from July until Oct in Qom and from Aug. until Oct. in Saveh. The highest diversity of parasitoids and the most parasitism percentage level was observed in Varamin. The highest percentage of fruits attacked by E. ceratoniae was found in the near harvest, period, starting in Oct. The percentage of infested fruits in the agricultural season was approximately 69.25% in Varamin, 47% in Qom and 56.25% in Saveh during October. This is the first report of parasitism of carob moth larvae by all species belonging to Ichneumonidae, Chelenus sp. (Hym.: Braconiade) and Fischeria bicolor (Dip.: Tachinidae) in the world. According to the obtained results, diversity of parasitoids and parasitism percentage of carob moth larvae is so considerable that many further studies on their control, and the conservating methods of the valuable natural treasures that can fall prey to them should be conducted.

Elimination of Potyviruses from two commercial Iranian garlic populations, Hamedan and Azar-shahr, through thermotherapy and by meristem tip culture were investigated. The infected bulbs of either one of the populations were initially treated at 30o C for one week and then at 36oC for 5 weeks. The meristems of cloves at two sizes of 0.4-0.6 mm and 0.6-0.8 mm were then cultured on MS medium supplemented with NAA and BA. Following the growth of explants, ELISA test was performed to detect infection to potyviruses. The elimination rate of potyviruses in explants that were produced from small size meristem cultures was higher than in those produced from the bigger ones, obtained as 100% and 91% for meristem cultures of 0.4-0.6 mm, and 0.6-0.8 mm in size, respectively. In samples with mere thermotherapy and without any meristem tip culture, elimination rates were 73% and 61% for Hamedan and Azar-shahr populations respectively. Control plants (non-treated) showed than 80% infection rate. Growth regulator, NAA at a concentration of 0.1 mg/l, exerted a significant positive effect on proliferation, growth of plantlets and on the number of leaves. BA at concentrations of 0.1 and 0.5 mg/l significantly and positively affected proliferation and the number of leaves. Interaction of cultivars and meristem size had significant positive effects on only plantlet length. Treatment S2C1 bore the highest plantlet length.

Two yeast isolates, A4 and A5 of Candida membranifuciens and one isolate, A6 of Pichia guilliermondii were tested either separately or in mixture for their effectiveness against apple gray mold, caused by Botrytis cinerea Pres.: Fr. As regards the compatibility of the biocontrol agents, it was shown that yeast isolates were compatible with each other in liquid media. Results of the experiments carried out on germination of pathogen spore in liquid media and in dual culture showed that inhibition varied from 14.39 to 37.73% in dual culture and from 11.66 to 46% in liquid media. The lesion area caused by B.cinerea when apple inoculated with 1x108 cells/ml alone or a mixture of them was less extensive than that in the control. This is while a combination of A6+A5 was the most effective in reducing grey mold when apple incubated at 20 or 4oC. These results indicate that by using yeast mixtures, it is possible to improve biological control of the disease.