فصلنامه گیاه پزشکی
سال سی و هفتم شماره 2 (تابستان 1393)

According to the classical concepts, the smut fungi are plant parasitic Basidiomyceteous microfungi possessing teliospore. 1640 smut species have been reported from the world until 2012. In this study, 19 species of the smut fungi were obtained from Hamedan province which were identified as Ustilago turcomanica, U.hordei, U. tritici, U. bullata, U. cynodotis, U. maydis, U. phrygica, U. hypotydes, U. striiformis, Tilletia laevis, T. bornmuelleri, Anthracoidea eleocharidis, Sporisorium cruentum, S. reilianum, S. schweinfurthianum, Microbotryum tragopogonis- pratensis, Urocystis gladiolicola, U. colchici, U. muscaridis. In order to confirm tentative morphologicallyidentified U. hordei on rye, ITS regions (ITS1. ITS2 and 5.8s gene) of ribosomal DNA from this species were sequenced. Results of the molecular study proved morphological diagnoses. Among the identified species, Urocystis muscaridis on grape hyacinth (Muscari neglectum), Urocystis colchici on autumn crocus (Colchicum autumnale), Ustilago hordei on rye(Secale montanum), Ustilago striiformis on timothy-grass (Phleum pretens(, U. phrygica and T. bornmuelleri on medusahead (Taeniatherum crinitum) are considerd to be the first report from Iran. In addition, Goatgrass (Aegilops cylindrica) is a new host species for Ustilago tritici in the world.

The use of resistant plant cultivars could be an effective strategy in integrated pest management of rice. Resistance and susceptibility of three selected rice lines (8615, 8405, 1-23-DN and Tarom variety as check) to the striped stem borer (S.S.B.), was investigated in the in greenhouse of Iran Rice Research Institute during 2010-2011. Seedlings of 30 days were transplanted in pots and were placed in randomized complete design with four treatments and four replications in four separate cages. The egg mass of striped stem borer on the leaf was used for host preferance. Larva weight mean and the survival percentage of larva were evaluated for antibioses resistance and percentage of white head and reducing yield was used for estimation of tolerance to the striped stem borer. Data was compared by One-way Analysis Of Variance (ANOVA) followed by LSD test. Parameters were analyzed by using the SAS software. The results revealed that there was no significant differences in the size of egg masses in the first generation and larvae weight mean, but there were significant differences in the size of egg masses in the second generation, survival percentage and white head among the cultivars. Also, a meaningful relationship was found between egg masses and plant height, leaf blade and (50%) panicle excretion. A negative relationship was observed between larvae weight mean and tillers number.

Fumigant toxicity of Eucalyptus camaldulensis (Dehnh) and Callistemon viminalis (Gaertn) essential oils was investigated against adults (1-3 days old) of Oryzaephilus surinamensis L. and Cephalonomia tarsalis (Ashmead). The essential oils were obtained by the hydrodistillation method, using a modified Clevenger apparatus. The experiments were carried out at 27± 1 °C and 65 ±5% R.H. in a dark condition. Results of fumigant toxicity tests showed that mortality was increased with the increase in concentration and time. The lethal concentration of E. camaldulnsis and C. viminalis to cause 50% mortality of O. surinamensis (LC50) was estimated to be 3.27 and 1.42 µL/L air and for C. tarsalis LC50 values were 0.52 and 0.72 µL/L air, respectively which indicated more susceptibility of C. tarsalis compared to O. surinamensis. The lethal time to kill 50% of the adults (LT50) at concentrations of 35.71, 32.14, 28.57 and 25 µL/L air lasted 5.84, 5.59, 5.34 and 4.94 h for E. camaldulnsis oil and 4.33, 3.93, 3.61and 2.09 h for C. viminalis, respectively. The persistence of essential oils of E. camaldulensis and C. viminalis at 35.71 µL/L air against O. surinamensis was 11 and 6 days, and for C. tarsalis, the oil persistence reached 56 and 20 days, respectively.

The Sunn Pest (Eurygaster integriceps Put.) is the most important pest of wheat and barley fields in Iran. For mass rearing of egg parasitoids, an appropriate host is necessary. One of the hosts is the egg of sunn pest. Diapause of sunn pest is one of the limitations for egg production. The aim of this study was to inhibit the diapose of sunn pest with the use of juvenilhormon mimic (admiral) and to determine the procentae parasitism of the egg by Trissolcusgrandis Thomson. Collected Eurygasterintegriceps adults from overwintering sites in July, August, September and, October, were maintained on dry wheat grains and water was provided with a piece of wet cotton in laboratory conditions at 25± 3 Co, 50- 60% RH, and 16:8 (L:D). This experiment included 4 treatments (July, August, September and October) with 4 replications. Ten males and ten females of Eurygasterintegriceps were released in each replication in a ventilated cage (20*30*15cm). Admiral 10% (at the concentration of 0.002) was applied topically on the ventral abdomen of Sunn pest. Furthermore, a control treatment without admiral was considered. The data were analyzed using SPSS and the means were compared by Duncans multiple range test. Results indicated that admiral interrupted the diapose of sunn pest in the above mentioned months, and induced mating and oviposition. When different months were compared the highest percentage of ovipsition (39.6%), the lowest percentage of unhatched eggs (17.25%), the lowest percentage of dead adults (10%) and the highest percentage of egg parasitism (60%) were observed in July. It could be concluded that July is the most appropriate time for interrupting diapause of Eurygasterintegriceps which can be used for the mass reerying of Trissolcusgrandis. In adation, no parasitoid adults emerged from the parasitized Eurygasterintegriceps eggs.

Nowadays, Jasmine whitefly Aleuroclava jasmini (Takahashi) (Homo: Aleyrodidae) is the most important pest of citrus orchards in Khuzestan province, Iran. In order to determinate the most proper sample unit and universe of Jasmine whitefly population, some experiments were carried out in a 0.8 ha grapefruit orchard using one, two or three ways factorial experimental design with three replications at different times in 2010 and 2011. Some factors like the situation of one cm2 quadrats on undersurface of leaves (five situations), four heights (0.75, 1.5, 2.5 and 3.5 m above ground level), four geographic directions and the situation of leaves on 30-40 cm branches (at 16 levels) were studied. The number of immature population was counted on the undersurface of the leaves. Using mean population (m), RV and RNP indices and regression relationships revealed that one cm2 quadrates are suitable for assessment of population. But counting the population of eggs on the mid rib at the base of the leaf and also counting the population of nymphs on the widest portion of the leaf blade were determined as the appropriate sample unit. The height of 1.5 m was considered the most suitable for sampling at all times. There was no significant difference among geographical directions for RV values, although the north direction had the highest correlation with the total population on trees, so sampling from the north direction is preferred. From the end of branch, 10th to 14th leaves on March, first to 5th leaves on April, 6th to 7th on July and 9th to 12th on January had the least values of RV, so the best leaves for sampling from branches were changed by the passage of time.

Parasitoids cold storage is the most commonly used method for the storage of natural enemies. In this research, the cold storage feasibility of larval and pupal developmental stages of Lysiphlebus fabarum was studied at 4 °C. The effect of constant or fluctuating temperatures on these developmental stages was also considered. The three-week maintenance in different treatments showed that mummy/fluctuating temperature treatment was the best storage condition because the highest emergence rate and sex ratio and the largest offsprings were observed in this treatment. In this study, the lower temperature threshold for oviposition was also determined. For this purpose, mated females were introduced to black bean aphids for 24 hours at 4, 6, 8, 10 and 12 °C. The results showed that the females started laying eggs at 10 °C. At this temperature, all emerged adult were male while, at 12 degrees, both sexes were observed.

In this study, the filtrates of two nematophagous fungus Arthrobotrys oligospora and A. conoides were evaluated for the inactivation rate of the second stage juveniles (J2) of Meloidogyne incognita and M. javanica. The filtrates were used at three concentrations (25%), (50%) and (100%) from original preparation. Experiments were done using Completely Randomized Factorial Design. Results showed that under laboratory conditions, fungal culture filtrates show various impacts on the second stage juveniles of M. incognita and M. javanica. About the second stage juveniles (J2) of M. incognita, after 24 hours the maximum toxicity belonged to a concentration 100% of A. oligospoa with inactivity of about 75,5%. Also the minimum toxicity belonged to a concentration 25% of A. conoides about 21.25%. At the same time, the highest rate of disabled second stage juveniles of M. javanica belonged to a concentration 50% of A. conoides about 43.17%. After 48 hours, both species showed inhibition; also, maximum toxicity belonged to a concentration 100%, of A. conoides on the second stage juveniles (J2) of M. incognita with inactivity of about 100%. while the maximum toxicity on the disabled second stage juveniles of M. javanica belonged to a concentration 100% of A. conoides with inactivity of about 98.6%. Finally, after 72 hours, 100% of the second stage juveniles (J2) of M. incognita and M. javanica was inactivated at a concentration of 100% of A. conoides.