نشریه پژوهش های کاربردی در گیاه پزشکی
سال چهارم شماره 2 (پاییز 1394)

The Cabbage butterfly, Pieris brassicae (Lepidoptera: Pieridae), is a cosmopolitan and a destructive cruciferous pest that has been widely distributed. The aim of the current study was to investigate the effect of proteinaceous extracts of mung bean, pea and two wheat cultivars against the Pieris brassicae midgut α-amylase. Results showed that effects of obtained extracts on amylolytic activity of Pieris brassicae was as a dose dependent manner namely with increasing dose, the amylase activity decreased. Also, the results showed highest dose (1/64, 2, 1 and 1 mg.ml-1) of mung bean, cowpea, Alborz, Kavir caused 16, 4, 51, and 55% inhibition of the insect amylase, respectively. Effect of pH on amylase showed that the greatest inhibition of amylase was observed at pH 8 which is the optimum pH for the activity of the enzyme in in-vitro condition. The results revealed that pH had significant effect on inhibition of wheat seed cultivars on this insect α-amylase. It is concluded that extraction obtained from seeds of wheat cultivars affected more α-amylase of the pieris brassica than pea and mung bean seeds. Thus, proteins present in the wheat cultivars have a good potential to be studied further in order to purify them, indentify their structures and investigate their specificity for α-amylase of different animals.

The discoloration of rice grains is a complex disease due to infection by certain microorganisms on the glumes, kernels, or both, and its extension is different according to cultivar, season and locality. To access resistance source to rice grain discoloration disease, 66 Iranian local and improved, and foreign cultivars of rice were grown at the Rice Research Institute of Iran in Rasht county. After panicle exertion, plants were kept wet to develop grain discoloration until the evaluation time by a water sprayer system, above the tested plants in the field. Assessment of cultivars was done by sampling of 15 main panicles in each cultivar, seven to 10 days before harvest. The recorded data analysis revealed a wide variability among cultivars in terms of disease index, percentage of unfilled seeds and 100 seed weight. On the bases of disease index results, the local cultivars Hassansaraei Attashgah, Ali Kazemi, Hashemi, Sadrei and Binam showed significant resistance reaction to grain discoloration disease in the field conditions. From the fungi that were isolated from discolored grain, virulence of Bipolaris oryzae, Fusarium fujikuroi, Fusarium graminearum, Curvularia sp. and Alternaria sp. were confirmed on two local and improved cultivars namely Binam and Khazar respectively, whereas no disease symptom was appeared due to Nigrospora sp. and Ulocladium sp.

Small walnut aphid (SWA), Chromaphis juglandicola (Kaltenb), is a pest of walnut trees in many regions. Population fluctuations as well as spatial pattern of distribution of small walnut aphid (SWA) was studied during growing season of 2012 by weekly samplings in Mamaghan walnut orchards, East Azerbaijan, Iran. Sampling program was conducted for about six months from late April to November. All stages of aphid were counted separately on 128 clusters of leaves collected from eight walnut trees. Discrepancy of the sampling data from whether Poisson (random) or negative binomial (aggregation) statistical distributions was investigated by Pearson's Chi square test. Disregarding stages of SWA, goodness of fit tests were carried out with total populations. Contagiousness indices as well as Taylor's power low were also used to distinguish the pattern of distribution. In all samplings from 10 May to 10 August, data fitted to negative binomial distribution only with two exceptions. Afterward population deeply declined and well fitted to random pattern up to 20 September. Relative increase of population in late season leads to a tendency to aggregation once again. As a conclusion, SWA colonization begins as random; aggregation occurs following on site reproduction of females and finally random situation returns following depletion of patches. A second aggregation occurs late in the season when autumnal natality regains. Taylor's power low also showed a clumped pattern with a slope of b=1.55.

Cucumber is one of the most important cucurbits in Iran. Cucumber mosaic virus (CMV) is one of the plant pathogen viruses with widest host range. Resistance induction in plants is one of the most effective methods in combating viral diseases. The effects of foliar spraying of chitosan (0, 500, 1000 and 1500 ppm(on molecular, biochemical, disease severity and virus concentration was investigated in greenhouse conditions through spraying of chitosan on cucurbit seedlings at two foliage stages, in a completely randomized design with three replicates. The results of enzyme linked immunosrobent assay (ELISA) and reverse transcription-polymerase chain reaction (PCR) proved systemic infection status of plants. The lowest amounts of virus concentration and disease severity were estimated as 0.46 and 40.7, respectively. Chitinase gene expression levels in chitosan foliar treatments with 500, 1000 and 1500 ppm, increased as 6.229, 11.703 and 14.19 times more than healthy control, respectively. The results of present study showed that chitosan treatment causes induced resistance, reduction of the concentration of virus and disease severity through increasing the expression of chitinase and peroxidase enzymes belonging to the families of pathogenesis-related protein, This study can be an introduction of chitosan usage for increasing expression (over expression) of these gens and providing induced resistance of cucumber to CMV.

Agricultural practices such as application of fertilizer and various cultivars of host plant can affect population parameters of the pests and their natural enemies. In this research, effects of using different vermicompost: soil ratios (0:100, 10:90, 20:80 and 30:70 %) as a growth medium of two cucumber cultivars (Khasib and Karim) were investigated against biological parameters of the melon aphid, Aphis gossypii Glover and its predator gall midge, Aphidoletes aphidimyza Rondani. The experiments were carried out in a growth chamber at 25 ± 2°C, 65 ± 5 % RH and a photoperiod of 16:8 h (L:D). The longest and shortest longevity of the aphid was obtained at 0:100 % ratio of Khasib and at 30:70 % ratio of Karim. The highest total fecundity of the aphid were at 0:100 % ratio for both Khasib and Karim and lowest fecundity of it was at 30:70 % ratio of Karim. The shortest incubation period of A. aphidimyza was observed at 20:80 and 30:70 % ratios of Karim and at 30:70 % ratio of Khasib. The shortest larval period was also at 30:70 % ratio of Karim. The total fecundity of predator increased with increasing the vermicompost ratios. The results revealed that most biological parameters of the A. gossypii and A. aphidimyza were affected by the type of cultivar and dosage of vermicompost fertilizer. Therefore, intergration of the both cultural methods and natural enemy can lead to better controlling of the melon aphid in integrated pest management programs especially in greenhouse cultures.

Trichoderma species are of important antagonist agents in plant pathogens biocontrol. These agents utilize different mechanisms in their biocontrol activities such as production of extracellular enzymes. In order to evaluate the ability of antagonist and pathogenic fungus in producing extracellular enzymes, specific culture media such as amylase, cellulose, laccase, lipase and protease were prepared. Subsequently, each antagonist and pathogenic fungus was separately inoculated on the appropriate media and incubated for 3-5 days in 25±1°C. Results indicated that T. atroviridae (1-3), T. virens (6011) and F. oxysporum produced amylase, cellulase and laccase. T. koningii was only able to produce lipase enzyme. T. harzianum (Ahmedabad) produced amylase and cellulase but not laccase. T. atroviredae (6022) produced laccase but, was unable to produce amylase and cellulase enzymes. The results of the dual cultures, leads to T. harzianum (Ahmedabad) compared with other Trichoderma species had maximum growth inhibition on amylase and cellulase medium. While the dual culture assay of laccase medium indicated that the higher activity percentage of growth inhibition in F. oxysporum species compared with antagonists was significantly different.However, it seems each substrate during interaction of Trichoderma species with Fusarium sp., had different specific action due to enzyme production.

Efficacy of propamocarb hydrochloride + fosetyl aluminum (Previcur® Energy SL 840) in controlling of cucumber damping-off (Phytophthora drechsleri) was studied in comparison with metalaxyl (Ridomil® G 5%) under field and greenhouse conditions. Trials were done at CRBD during two years by three methods as soil drench, soil incorporation and their combination. The results of the field and greenhouse trials showed that there were significant differences between treatments. Combined mean comparison of two years in micro plot trials revealed that Previcur Energy at 2 and 3 ml/m2 rates had the same effects in disease control so that it decreased the disease by the 78% compared to the control. In this trial Ridomil at the rate of 2.5 g/m2 decreased the disease by the 68.4% compared to the control. The results of the greenhouse trials showed that there was no significant difference between Previcur Energy at the rates of 200, 300 and 400 ml/m3 of soil and 0.2, 0.3 and 0.4% in all application methods at the statistical level of 5 and 1%. These results revealed that Previcur Energy at applied rates decreased disease by the 66.6 to 91.26% compared to the control. However Ridomil 250 g/m3 and 0.25% decreased the disease rate by 45.74 to 63.52% compared to the control. Comparison of the effects of treatments in controlling disease through the different application methods demonstrated that two time application of Previcur Energy and Ridomil as soil incorporation at pre-sowing and soil drench at the two leaf stage had the best effects.

One of the methods of plant disease control especially in organic farming is the use of natural ingredients. In this study, the inhibitory effects of volatile and non-volatile metabolites of wood vinegar (Pyrolignious acid) on the mycelial growth of Phytophthora drechsleri and Pythium aphanidermatum and on the growth traits of the greenhouse cucumber were studied in vitro and in situ conditions. To study the effect of non-volatile metabolites, mycelial disks were placed on PDA culture medium containing 0, 0.025%, 0.05%, 0.125%, 0.25%, 0.37%, 0.5% and 0.75% of wood vinegar. To study the effectual volatile metabolites mycelia disks placed on one side of walled-petridishes, while on the other side, the above-mentioned concentrations were added. Both volatile and non-volatile metabolites inhibited significantly (at 0.05 probability level) the fungal growth P. aphanidermatum and P. drechsleri in vitro conditions. In greenhouse conditions, cucumber seedlings were transplanted into pot soil inoculated with fungus. Three concentrations of wood vinegar showed the maximum inhibitory effect on mycelial growth. Disease severity was significantly reduced in all concentrations used (α= 0.05). All concentrations of wood vinegar significantly increased the weight, length and height of the plants compared to the control (α= 0.05).

Cotton boll worm "Helicoverpa armigera" is one of the most important pests in cultivated crops. Physiological understanding is one of the basic steps to control pests by chemicals and pathogens. In this study, Lipase enzyme characteristics in mid gut of cotton boll worm were studied. Studying of enzyme activity and other treatments were done by Auto analyzer and chromogenic method. The highest and langest enzyme activity were observed in the 6th instar larvae and male adults, respectively, The highest enzyme activity was observed at 40°C. Optimum pH for lipase enzyme activity in the mid gut was 9.5. After eight week enzyme activity at -20°C was 17% of its activity in the first week. While enzyme activity at 4°C after five weeks, was 6% of its activity in the first week, then enzyme activity completely stopped. The results of the study of enzyme activity at different times of starvation showed that enzyme activity after four day starvation was reduced to approximately 9% of its activity when larvae had fed. Enzyme activity was decreased by ethanol 96%, and 3, 4 and 5mM of NaCl and 3, 4 and 5mM of CaCl2 and different concentrations of SDS. Enzyme activity was increased by 1 and 2mM of NaCl and 5mM of KH2PO4. Different concentrations of Tris, EDTA concentration up to 25% ethanol and 4mM of KH2PO4 also had no observed effect on enzyme activity.

In this study, efficacy of Paya® (Iranian diatomaceous earth) in different doses and exposure intervals on different grains evaluated against adults of the granary weevil, Sitophilus granarius (Col.; Curculionidae). All experiments carried out at 26 ± 2ºC, 65 ± 5% R.H., and continuous darkness. Adults’ mortality counted after 1, 2, 7 and 14 days on wheat, barley, rice and maize kernels treated with five dose rates of 0.125, 0.25, 0.5, 1 and 1.5 g/kg-1. To assess progeny production, all dead and alive adults were removed and treated grains left at the same conditions for 45 more days. Then, the number of adults emerged on treated grains was counted. Insecticidal efficacy of Paya® was highly affected by the type of grain, dose rate, and exposure interval. Observed mortalities after 1 and 2 days on four grains were very low for all doses. After 7-day interval, highest mortalities on wheat, barley and rice (14.52, 11.61 and 6.69 percent, respectively) occurred by using the highest dose, but in the case of maize, mortalities caused by doses of 0.5, 1 and 1.5 g/kg-1 reached up to 35.27, 40.90 and 38.26 percent, respectively. Insecticidal efficacy of Paya® was only notable on maize after 14-day interval and by using high doses of 1 and 1.5 g/kg-1 and it reached up to 95.83 and 90.14 percent, respectively. Evaluation of progeny production showed that numbers of F1 adult progenies were higher on barley (14.75-25.75 adults) and wheat (4.75-21.75 adults), respectively. The lowest progeny productions were also observed on rice (0.0-0.25 adults) and maize (0.5-3.11 adults), respectively, which had no significant differences at all doses used. As a conclusion, 100% control of adults of this pest especially on barley and wheat is needed for suppression of population increase at F2 and following generations.

Mealybug destroyer, Cryptolaemus montrouzieri Mulsant is the most important natural enemies of the citrus mealybug, Planococcus citri (Risso). Life table parameters of C. montrouzieri feeding on citrus mealybug, P. citri was studied at eight temperatures ranging 13 to 35 (±1) °C, 60 ± 10 % RH and a photoperiod of 16:8 (L:D) h. in growth chamber. Development of the coccinellid did not complete or laid eggs were infertile at temperatures 13, 15, 30, 33 and 35 °C. Therefore, life table parameters were estimated only in three temperatures, 20, 25 and 27°C. Construction of the life table and calculation of its parameters was conducted using Carey procedure. According to the results, the maximum and minimum values of the net reproductive rates (Ro) were 208.48 and 77.52 female/female/generation at 20 and 25°C, respectively. The values of finite rate of increase (λ) at the same temperatures were 1.04, 1.14, and 1.08 day-1, respectively. The maximum values of intrinsic rate of increase (rm) were 0.085 female / female / day and shortest mean generation time (T) was 57.37 days, at 27 °C. Estimated values for the doubling time (DT) were 15.56, 8.30 and 8.09 days at temperatures 20, 25 and 27°C, respectively. The results confirmed that temperature has a significant effect on population increase of the predatory coccinelid, C. montrouzieri and 27°C is the optimum temperature for population growth of C. montrouzieri among examined temperatures.

Tomato leaf miner, Tuta absoluta Meyrick is one of the most destructive pests of tomato in the world. In Iran, it was reported for the first time in 2010 from West Azerbaijan province. The pest feeds on foliage of the host plant and causes damages by reducing plant growth, creating galleries in leaves, making damage on fruits and reducing the marketable quality of the yield. Chemical method is the main measure for controlling the pest in the most parts of the world. In current study, the effects of indoxacarb and emamectin benzoate were studied against 2nd larval instar of tomato leaf miner. Rearing of the pest was carried out at 25±1 °C, 65±5% RH and a photoperiod of 16:8 (L: D) h. Bioassays were done on the larvae by leaf dipping method. Each concentration included three replications and there were 10 larvae for each replication. Treatments consisted of five concentrations for each pesticide and one for control. Insect mortality was recorded 24 h after initial exposure. In addition, sublethal effects of emamectin benzoate and indoxacarb were studied on some of biological parameters of the pest. LC50 values for emamectin benzoat and indoxacarb were 2.13 and 25.87 mg/L, respectively. Emamectin benzoat was more effective against 2nd instars larvae compared to indoxacarb. The sublethal effect study results showed that emamectin and indoxacarb reduced longevity, fecundity and pupal weight and increased larval and pupal periods. Overall, the results showed that emamectin benzoate has high potential for controlling tomato leaf miner.

In this study, antagonistic potential of fungal agents inhabiting rhizosphere of sugarbeet were evaluated against Cercospora beticola, the causal agent of sugarbeet leaf spot disease. For this purpose, 15 fungal isolates were recovered from rhizosphere of sugar beet plants. After preliminary screening of their antagonistic potential, three isolates were selected for further antagonistic assay. Isolates were identified based on the sequence data of ITS-rDNA region. The identity of isolates was determined as Trichoderma harzianum, Acremonium strictum and Geliocephalis sp. Three additional antagonistic fungi namely T. harzianum (T22), T. harzianum (Ta) and Hansfordia pulivinanta (Ha) were also included in current experiment. The results obtained in this study showed that all of the antagonists significantly inhibited the growth of C. beticola in compare to the control. In dual culture and volatile secondary metabolite assays T. harzianum T22 showed the highest inhibitory effect and A. strictum and Geliocephalis showed lowest inhibitory effect on C. beticola. In non-volatile secondary metabolite (autoclaved and non- autoclaved) assay, the highest and lowest inhibitory effects were recorded for T. harzianum and A. strictum, respectively. Antagonistic potential of Trichoderma isolates were further evaluated under greenhouse conditions in three different statuses including application of antagonists prior to, simultaneous and after inoculation of C. beticola on sugar beet leaves. The obtained results showed that both Trichoderma isolates significantly reduced the disease severity in compare to the control.

Vine Cicada, Psalmocharias alhageos (Hom.: Cicadidae), is a key pest of vine in Iran. Pest nymphs feed on vine roots sap and their adults damage the vines by ovipositing in branches. In a field study, during two years based on a random complete block design, with 8 treatments and 6 replications, the efficacy of two formulations of Fipronil (SC 5% and G 0.02% g/vine) at different concentrations, imidacloprid (Confidor® 350SC) (at 20 ml/vine) and cartap (Padan 0.5% g/vine) were assessed against Vine Cicada in Hamedan province. Treatments were applied in March 2012 and 2013, by making a 20-cm groove with a radius of one meter at under the canopy of vines. The number of nymphal exit holes and vine yield were subjected to analysis of variance followed by Duncan’s test. Based on The results 2012 and 2013, number of exit holes were observed for imidacloprid (3.33, 0.43), Foreign fipronil at 50 g (4.86, 1.56), and Iranian imported fipronil at 50 g of granule /vine (5.76, 1.68), respectively. The highest yield was observed in imidacloprid (3216.7, 3000 g/grape cluster) and Iranian fipronil at 50 g of granule /vine (2966.7, 2900 g/grape cluster), while the lowest yield was observed in control (566.7 g/grape cluster, 483.3 g/grape cluster) in two years stung, respectively. Based on our results, fipronil (G 0.02%) (at 50 g/vine) and imidacloprid (Confidor® SC 350) at 20 ml/vine can reduce population of vine cicada and increase yield if applied at suitable time.

The sugar beet weevil, Lixus incanescens Boheman, is one of the important insect pests of sugar beet, Beta vulgaris L., in Khorasan Razavi province. In this research, the effect of three types of vegetation in the sugar beet field margin on the population density of L. incanescens and its larval parasitism by parasitoid wasps were studied in the experimental fields of Juvein, Khorasan Razavi province from year 2013 to 2014. In this study a sugar beet plant was selected as sampling unit. In two years, the lowest density of eggs (6 and 6.3 eggs per plant, respectively) and larvae (3.1 and 3.3 larvae per plant, respectively) was recorded in the sugar beet field located nearby forage with trees. Also, four larval parasitoid species of L. incanescens including Bracon intercessor Nees, B. kozak Telenga, Eurytoma aciculata Ratzeburg and E. ghilarovi Zerova were collected and identified from the experimental fields. Among identified four parasitoid species, B. intercessor had the highest percentage of larval parasitism in two years (69 and 76%), respectively. In addition, the highest percentage of larval parasitism by each of four parasitoid species and the highest percentage of females of each of them were observed in the sugar beet field located nearby forage with trees. Therefore, it can be concluded that the presence of forage with trees on the margin of the sugar beet fields can increase larval parasitism and reduce population density of L. incanescens. These results could be useful in integrated management of L. incanescens in the sugar beet fields.