Journal Of Crop Protection
Volume:9 Issue: 1, Mar 2020

One critical environmental stress that limits plant production and development is salinity stress. Recently it has been shown that application of plant growth-promoting rhizobacteria (PGPR) can alleviate the deleterious effects of environmental stresses. Present study aimed to evaluate the effects of some bacterial strains on proline, sugar, total phenolic compounds (TPC), Phenylalanine ammonia lyase (PAL), photosynthetic pigments and antioxidant activities (guaiacol peroxidase, polyphenol oxidase and superoxide dismutase) of cucumber plants under salinity stress. A completely randomized design was applied with a factorial arrangement of two factors: salinity at three levels (0, 50 and 100 mM) and Pseudomonas fluorescens and Bacillus subtilis strains, with three replications. The results showed that cucumber plants that were inoculated with Pseudomonas and Bacillus strains possessed noticeable variations in proline, sugar, TPC, PAL and enzymes activity compared to un-inoculated control. These results suggest that use of these bacterial strains overcame harmful effect of salinity by accumulation of proline, TPC, sugar, PAL activity and enzymes activity that can be considered as a suitable method to manage salinity stress.

The two-spotted spider mite (TSSM), Tetranychus urticae Koch (Acari: Tetranychidae) is a serious pest of many greenhouse crops such as bean, cucumber, rose and other products. The control of this important pest has been mainly based on the use of acaricides. Phytoseiid mites are used mostly for biological control of pest mites. In this study, control of TSSM by phytoseiid predatory mites, Phytoseiulus persimilis Athias-Henriot, Amblyseius swirskii Athias-Henriot and Neoseiulus californicus McGregor was evaluated on four rose varieties including Avalanche, Dolcevita, Samurai and Sorbet in a commercial rose greenhouse. The total number of motile stages and eggs of each studied species on a leaf were counted weekly, through a zigzag sampling pattern and using a hand lens. The sampling was carried out randomly and the leaves of a rose plant were taken from the canopy base (shoots bent over beds), the middle (area between base and top) and the top of the canopy (flowering shoots), which added up to a total of 30 leaves. The highest population density of TSSM per leaf was recorded on Samurai (17.96 ± 0.85) and the lowest population density was observed on Dolcevita (5.32 ± 0.39). Based on population fluctuation data of TSSM and its predators on four rose varieties, it was found that the predatory mite P. persimilis had the ability to reduce the high TSSM density and N. californicus also continued to operate in low TSSM density, but A. swirskii did not have a clear impact on TSSM density reduction.

The Mediterranean flour moth, Ephestia kuehniella (Zeller) (Lep.: Pyralidae) is not only known as stored products pest, but also used as a potential factitious host for mass rearing of biological agents. The aim of this study was to evaluate the effect of five different cereal cultivars (Wheat: Homma, Mihan and Zareh; Corn: 704 and Barley: Makui) on feeding performance and life table parameters of E. kuehniella, which was estimated by Carey life table producer. The results showed that preadult period ranged from 46.91 to 59.00 days on Corn and Zareh, respectively. The highest and lowest net reproductive rates (R0) were obtained on Homma (128.76) and Zareh (61.77) offspring/female, respectively. The highest values of the intrinsic rate of increase (r) and finite rate of increase (λ) were on Corn and Homma and the lowest was on Zareh (r: 0.079 day-1, λ: 1.08 day−1). Based on the life history and demographic parameters results, Corn and Homma were the most suitable hosts for E. kuehniella. These findings may provide helpful information in integrated pest management programs including rearing of E. kuehniella as the alternative host, which could be used in the mass production of natural enemies.

For successful implementation of integrated pest management (IPM) programs, having knowledge on lethal and low-lethal effects of pesticides on natural enemies is necessary. The present study evaluated the low-lethal effect of thiamethoxam on life table parameters of the subsequent generation of the predatory mite, Neoseiulus californicus McGregor (Acari: Phytoseiidae) fed on Tetranychus urticae Koch under laboratory conditions. The low-lethal concentrations LC5, LC10 and LC20 were determined based on a dose-effect assay. The raw data were analyzed based on age-stage two sex life table analysis. Exposure to the low-lethal concentrations of thiamethoxam had no significant effects on developmental time of offspring of treated mites. Compared with control treatment, the oviposition period of treated mites with LC5, LC10 and LC20 decreased significantly. The highest and lowest values of total fecundity were obtained at control (35.3 eggs/female/day) and LC20 (23.6 eggs /female/day), respectively. The net reproductive rate (R0) decreased with increasing dose from LC5 (22.6 offspring) to LC20 (15.0 offspring). The intrinsic rate of increase (r) and finite rate of increase (λ), were not affected by increasing concentrations. The mean generation time (T) decreased significantly at upper dose (LC20 = 13.2 d), compared with control (14.7 d). In consequence, the low-lethal concentration influences of thiamethoxam in combination with N. californicus in order to design management programs of T. urticae are discussed.

The egg-larval parasitoid, Ascogaster quadridentata Wesmael (Hym.: Braconidae) was stored for six months in the mature larvae of codling moth (CM), Cydia pomonella (L.) (Lep.: Tortricidae), under diapause conditions. Percentage of parasitoid adults (wasps) emerged from CM larvae reared under diapause conditions was about 86.6%. The biological characteristics (weight and longevity) were similar for both wasps that were treated under standard and diapause conditions. The data showed that percentage of parasitism for females emerged from standard conditions was 86.4%, while increased significantly to 97.8% for females emerged from diapause conditions. These findings may contribute to the mass rearing of A. quadridentata.

The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae) is one of the most destructive insect pests, feeding exclusively on wild and cultivated cruciferous species. The attacked plants produce considerable amount of glucosinolates in response to insects’ feeding. Herein, we studied digestive activities of P. xylostella on four different genotypes of family Brassicaceae including two canola cultivars (SLM046 and RGS003) and two cabbage cultivars (Green-Cornet and Glob-Master). The highest proteolytic and amylolytic activities of P. xylostella were observed on Green-Cornet and the lowest occurred on RGS003 and Glob-Master, respectively. The highest activity of α-glucosidase and β-glucosidases were observed on Green-Cornet and SLM046 and the lowest was observed on Glob-Master and RGS003. The zymogram analysis revealed different isozymes of protease, trypsin-like and α-amylase in the midgut extract of P. xylostella. Activity of the above mentioned isozymes was inhibited in larvae feeding on RGS003 and Glob Master as resistant host cultivars. Also, larvae feeding on the resistant genotypes showed more glucosidase activities, indicating possibility of high glycosinolate existence in the resistant genotypes. By these results we can state that host plant property can affect insect digestive physiology through inhibiting digestive enzyme activities. These findings provide insights into the direct effects of host plants on insect physiology which are conducive to change in insect fitness.

Potato tuber moth (PTM), Phthorimaea operculella (Lep.: Gelechiidae) is a serious pest of potato, Solanum tuberosum (Solanaceae). To study factors influencing capture of male PTM by pheromone traps, two sets of experiments were conducted in a split-plot factorial design. In the first experiment, four factors were studied: potato cultivar (Agria, Marfona, Jelly, Arinda, Santea and Sabalan), storage type (cold and conventional), trap shape (funnel and delta) and trap color (white and green). Significant differences were found among storage types and potato cultivars. Total moth catches were eight times higher in conventional storage than that of cold storage. Agria and Marfona cultivars had the highest capture, while Arinda and Sabalan cultivars had the lowest. There were no significant differences between trap shapes and trap colors. Results showed that trap catches in different cultivars were affected by storage conditions. In cold storages the highest and lowest captures were 7.00 and 5.58 moth/trap/week, whereas in conventional storages the highest and lowest captures were 59.9 and 42.3. The second experiment was aimed to assess the effect of cellulose mulch on the capturing of PTM in conventional storages containing Agria. Results showed that pheromone traps in control (no-mulch) treatments caught three times more PTM than the mulched treatments. It is concluded that lower numbers of PTM were caught in potatoes held in cold storages than that of conventional storages. Otherwise, in conventional storages, cellulose mulch can be applied to reduce PTM population density.

​Trichogramma evanescens Westwood is an important biological control agent of lepidopteran pests and is widely distributed throughout Iran and neighboring countries. Laboratory studies were conducted to determine the influence of Ephestia kuehniella Zeller eggs age on the number of parasitized eggs, development time, sex ratio, progeny longevity and fecundity. Understanding this influence is important for developing biological control programs. Mated female parasitoids (24 h age) were provided with 1, 2, 3, and 4-days-old E. kuehniella eggs in no-choice experiments, individually. T. evanescens developed on E. kuehniella eggs of all ages tested, while showing a better adaptation to younger host eggs with significantly faster developmental time, higher survival and more female progeny on 1-day-old eggs. Progeny emerged from 1-day-old eggs had also higher longevity and fecundity than those emerging from other host ages tested. The intrinsic rate of increase (r) values of T. evanescens reared on 1, 2, 3 and 4-days-old E. kuehniella eggs were 0.345, 0.322, 0.281 and 0.233 day-1 and the mean generation time (T) was 12.19, 12.13, 12.01 and 11.82 days, respectively. The current study provides useful information to use suitable host age of E. kuehniella for mass production of T. evanescens.

In this study, the effect of three temperatures was investigated on the functional response of Orius laevigatus to Aphis gossypii in climatic chambers at 20, 25, and 30 ± 1 °C, 60 ± 5% RH, and 16:8 h photoperiod. Different densities of first and second instar nymphs of A. gossypii (2, 4, 8, 16, 32, and 64) on cucumber leaf discs (6 cm in diameter) were separately offered to male and female predators. After 24 h, the number of consumed preys was recorded. Ten replicates per each aphid density were used. Based on the results, predator male and female exhibited types II, III, II and III, II, III functional responses at 20, 25 and 30 °C, respectively. Handling times (Th) for males were 0.7798, 0.9177 and 0.4476 h and for females were 0.6874, 0.3921 and 0.2831 h at 20, 25 and 30 °C, respectively. Using the indicator variable method, pairwise comparisons of handling times of both males and females were significantly different. The theoretical maximum predation rate (T/Th) of both males and females were obtained at 30 °C. The results revealed that O. laevigatus is more likely to be an effective biocontrol agent of A. gossypii at higher temperatures around 30 °C. However, additional studies under natural conditions are needed to provide further details of the predator-prey interactions.

Pistachio endocarp lesion (PEL) is one of the most important disorders that has spread in the pistachio-growing regions of Rafsanjan and Anar in recent years and has caused great economic losses to farmers. In order to identify PEL symptoms, and investigate the biologic factors involved in the development of this disorder, on May 2016, 90 orchards with different levels of PEL, were randomly selected. The rate of development in each tree was scored in- to four levels. The incidence of this disorder was estimated to be 25.8% in Rafsanjan. The seeds with PEL symptoms were differentiated into six types based on the appearance of the symptoms. Then tissue from infected parts of each type were cultured in the PDA. From among the 18 prepared culture media, fungal growth was obtained only in five cultured plates. Isolated fungi were Ulocladium sp. Penicillium sp., Verticillium sp. and Fusarium sp. To prove their pathogenicity, the spore spray technique was used on detached cluster in vitro. None of the purified fungi caused symptoms similar to the symptoms of PEL. Isolated strains from the pistachio seeds with PEL symptom often were saprophytic and soil borne; they were abundant in the orchard and could be transferred to the shoots of trees under the influence of various factors, such as: tillage, soil splashing by rain drops, and wind. In this study, the role of these fungal agents on the development of PEL was rejected.

Eleven species of Chalcidoidea (Hymenoptera) belonging to Aphelinidae, Encyrtidae, Eriaporidae and Signiphoridae associated with the cotton mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) were collected and identified during 2017-2018 from Khuzestan province in the southwestern Iran. Prochiloneurus rex (Girault) (Encyrtidae) is new record for the fauna of Iran. Meanwhile, biological associations of Bothriothorax serratellus (Dalman), Leptomastix dactylopii Howard and L. mayri Özdikmen (Encyrtidae) as parasitoids and Marietta picta (André), P. rex and Chartocerus kurdjumovi (Nikolskaya) (Signiphoridae) as hyperparasitoids of Ph. solenopsis were new.

Damping-off disease, caused by the fungus Rhizoctonia solani, is one of the most important diseases of cucumber plant and causes significant yield losses. R. solani possess some characters, such as wide host range and unlimited survival in soil, that make it as pathogen one of the most difficult agents to control. Therefore, the research for finding a biocontrol agent against this disease will be valuable. Two species of mycorrhizal fungi Glomus mosseae and Glomus clarum were evaluated against R. solani on cucumber plants. Mycorrhiza inoculated plants with both species showed a significant reduction in disease severity (DS), 21% and 25%, respectively, whereas the disease severity was 65% for non-inoculated plants. Furthermore, the effects of mycorrhizal fungi were evaluated on growth parameters of cucumber plants. Plants inoculated with both species of mycorrhizal fungi showed a significant increase in both shoot dry weight and root dry weight compared with noninoculated plants. It is concluded that both mycorrhiza species could be an important tool to control some soil-borne pathogens, increase plant nutrients absorption and increase resistance to abiotic stresses.

The genus Harrizia Delucchi, 1962 is represented by a single species, Harrizia mira Delucchi, 1962. This is first record of H. mira from Iran in the border of Eastern Palaearctic region and also the first record of this genus from Asia. The specimens were collected from Sistan-o Baluchestan and Kerman provinces in the South East of Iran. Brief diagnosis and illustrations of H. mira is provided and its distribution is discussed.

Analysis of genetic diversity of Fusarium verticillioides populations concludes different levels of information in management of crown and root rot disease in corn farms. Simple sequence repeat (SSR) markers were used to determine genetic structure and estimate genetic diversity in 77 F. verticillioides isolates from major producing areas in Ilam province, Iran such as: Dehloran, Mosiyan, Dasht Abas, Mehran, Eivan, Holeylan and Darreh Shahr during 2016 - 2017. Nine microsatellite (SSR) primer pairs revealed that the average number of alleles in populations were 34, the number of alleles in populations varied from 27 alleles in Dehloran and Mosiyan as the lowest to 40 alleles in Darreh shahr as the highest. Observed alleles (Na) number and effective number of alleles (Ne) were higher in Mehran (Na = 1.860; Ne = 1.463) compared to other populations. The genetic diversity (He) was higher in Holeylan (He = 0.284) and Shannon's information index (I) was also higher in Mehran (I = 0.436) but lower values were estimated for Mosiyan (He = 0.195; I = 0.303). The lowest genetic distance was found between Dehloran and Mosiyan (0.013) while the highest genetic distance was revealed between Dehloran and Darehshahr (0.139). Total gene diversity (Ht) and gene diversities between subpopulations (Hs) were estimated at 0.292 and 0.249 respectively. Gene diversity attributable to differentiation among populations (Gst) was 0.147, while gene flow (Nm) was 2.890. Cluster analysis based on UPGMA showed the lowest genetic distance between Dehloran and Mosiyan and then Dasht abas. The dendrogram indicated a high genetic distance between Darehshahr and the six remaining populations. Results from this study will be useful in breeding program of crown and root rot resistant cultivars and developing control methods for this disease.

The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) is one of the most important pest species, with an extended range of host plants in the world. Use of chemical acaricides is one of the principle ways of controlling this pest. Considering the resistance to acaricides, as well as undesirable effects of chemical compounds, finding a suitable alternative way to control this pest is necessary. In this study sublethal effects of Dayabon®, a herbal extract, were investigated on some biological parameter of T. urticae at 2.140 g/l (LC5), 2.682 g/l (LC10) and 3.526 g/l (LC20). The estimated LC50 for T. urticae adult was 5.950 g/l. When adults were treated with LC10 and LC20 of Dayabon, the oviposition period was significantly reduced compared to LC5. The highest and the lowest fecundity (number of eggs laid per female) were 56.02 offspring/individual in control and 39.11 offspring/individual at LC20 respectively. In addition the net reproductive rate (R0) was decreased as concentration increased. Whereas, intrinsic rate of increase (r) and finite rate of increase (λ) were not affected by Dayabon. Considering the detrimental effects of Dayabon on some biological parameters of T. urticae, it can be concluded that this product can be used to develop targeted interventions aimed at integrated management of T. urticae.