JWSS - Journal of Water and Soil Science

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The biology of predatory fly, Leucopis glyphinivora Tanas. was studied under greenhouse conditions. Adult longevity was 8 days and the average fecundity was 35.7 eggs. Incubation period, the 1st, 2nd, 3rd larval instars and puparium duration averaged 2.7, 2.16, 3.48, 5.7 and 8.45 days, respectively. Each generation lasted about one month. The predator efficiency was studied by applying the egg together with the adults of A. fabae at ratios of 1:1, 1:2, 1:4, 1:8 and 1:16 on broad bean. First larval instar was exclusively feeding on small nymphs (1st and 2nd nymphal instars) of aphid. Predator:prey ratios of 1:4, 1:8 and 1:16 decreased the number of prey to 97.9%, 98.8% and 61%, respectively, but ratios of 1:1 and 1:2 were unsuccessful in decreasing the number of preys due to predatory larvae leaving the host plant for searching small nymphs of aphid. As a result, the predatory larvae were efficient merely in a particular range of aphid density and age structure.

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Green lacewing, Chrysoperla carnea (Steph.), is one of the important natural enemies of cotton aphid, Aphis gossypii Glover. In this study, two experiments were conducted on cucumber plant in netted cages (70*70*40 cm) in a greenhouse. In the first experiment, Chryso-bags (special net bags with 360 holes per 2.5 cm² and 8 cm in width and 12 cm in length) were used. Seven treatments of release ratios included 1:1, 1:5, 1:10, 1:15 and 1:20 (predator: prey) and two control treatments with and without empty bags were compared. The experiment was conducted once in spring and once in autumn. In the second experiment, better release ratios were compared with two methods, Chryso-bag and sawdust as a carrier of eggs. Release ratios were 1:1 and 1:5 (predator: prey). Control treatments included only empty bag and sawdust, respectively. Results of the first experiment showed that the ratios of 1:1 and 1:5 were significantly different in spring, whereas they were not in autumn. The difference was probably due to the difference in temperature. Interaction between treatments and seasons showed that the ratios of 1:1 and 1:5 were not significantly different. In the second experiment, the release ratios of 1:1 and 1:5 in sawdust with each other and with 1:1 in Chryso-bags were not significantly different, while the ratio of 1:5 in Chryso-bag compared with 1:1 in both methods were significantly different. However, leaf necrosis was observed in the sawdust treatment.

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Greenhouse whitefly, Trialeurodes vaporariorum West. is one of the most important pests of the field crops and ornamental plants in greenhouses. Pest control is based on using chemical insecticides and biological control agents. In this study, the efficiency of the green lacewing, Chrysoperla carnea ( Steph.) with release ratios of 1:1, 1:5, 1:10, 1:15, and 1:20 (predator:prey) using eggs in chrysobag and the effect of three insecticides including Confidor (35% Sc), Permethrin (25% Ec) and Dimilin (25% Wp) at concentrations of 0.3 ml/l, 0.3 ml/l and 0.15 g/l in water, respectively, were investigated. In one experiment, the eggs of the green lacewing were released on tomato plants that were infested with 150 different nymphal instars of the pest. Control treatment included chrysobag whithout any egg. After 11 days, nymphal mortality was calculated. In insecticidal experiments, in control treatment, only water was sprayed. Both experiments were conducted in a randomized complete block design with four replications in a greenhouse with 25±5 °C, 50-60% RH and 14:10 LD period light conditions. The means of data were compared using Duncan Multiple Range Test. The results showed that the maximum nymphal mortality of 52.42% was due to the release ratio of 1:1 (predator:prey) however, this was not sufficient and did not control the pest population. The results of the chemical control also revealed that one application of Confidor caused the highest mortality about 88% that was more effective in reducing pest population compared with the release of predator eggs. Neither method had absolute control. In general, results indicated that to be more effective the two methods need to be applied more than once, and they must be combined into one or with other control methods.

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In order to study the nectar quantity and quality of some onion cultivars and honeybees foraging activity on them, a complete randomized block design with three replications was conducted. Ten selected onion cultivars consisting of Ghom, Kashan, Azarshahr, Dorcheh, Tarom, Kazeroon 1, Kavar, Abarkooh, Hurand, and Yellow Sweet Spanish were used. Sixty mm mother bulbs of different onion cultivars were planted in 3×4 m plots on 6 lines. The distance between rows was 35 cm and plants were spaced 25 cm apart on each row. At flowering time, bees’ activity on the inflorescences was studied and flower nectar was collected in 10 micro-liter capillary tubes. Nectar volume was determined and analyzed. Mean numbers of honeybees visiting on inflorescence every 10 minutes and the mean residing time of each honeybee on a seed stalk (inflorescence) were significantly different in different cultivars. Hurand flowers had the least number of visitors and Dorche flowers had the longest visiting time. The amount of nectar varied in different cultivars, so did glucose (G), fructose (F), and sucrose (S) contents. Except for the Abarkuh cultivar that had more glucose than it had other sugars, all the cultivars had higher quantities of fructose than they had other sugars while sucrose had the least quantities among the sugars. Nectar sugar ratio in most of the cultivars was hexose dominant, which was identified by the low S/(F+G) ratio. Potassium, calcium, and sodium contents in nectar were different in different cultivars, too. Finally, the results showed that foraging activity of honeybees on onion inflorescences depends on the interactions of several factors such as nectar quantity and, more importantly, on sugar quantity and ratio as well as potassium content. .

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The coccinellid Cryptolaemus montrouzieri Muls. is an oligophagous predator that is used to control mealy bugs in the orchards and greenhouses. Citrus soft scale, Pulvinaria aurantii, as an active pest on citrus plants in North of Iran is also attacked by this predator. This research was conducted to study biological characteristics of C. montrouzieri on citrus soft scale and mealy bug, Planococcus citri. Initially, Cryptolaemus eggs were collected from colonies of two preys and reared in laboratory (14 L: 10 D, 25±1˚C, and RH 70 ±5%). The incubation period of eggs, 1^st, 2^nd, 3^rd and, 4^th larval instars, and total larval, prepupal, and pupal stages were studied on two preys. The developmental stages on two preys were not significantly different, except for the 4^th larval instar at 1% and total larval stages at 5%. The sex ratio of male to female on two preys were not significantly different at 1% and was 1:1. Except for pre-oviposition period, other parameters including female longevity, average number of eggs laid per day, average total number of eggs laid per female and percentage of hatching were significantly different at 1% on the two preys. The average feeding of total larval period on eggs of mealy bug and citrus soft scale were 5715 and 7694, respectively that, the difference was significant at 1%. The results showed that some of the biological characteristics of Cryptolaemus on two preys were significantly different. Since the predator feeding on the eggs of citrus soft scale was higher than the mealy bug, it seems that this beneficial insect could be used for biological control of the citrus soft scale.

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Elm leaf beetle, Xanthogaleruca luteola (Müller), life and fertility tables were investigated under laboratory conditions (25±2°C, 70±5%R.H. and 16L: 8D), on Ulmus carpinifolia, U.c.var.umbraculifera, U. glabra var. pendula and Celtis caucasica, in spring and summer. Since the experiments were conducted under controlled conditions, feeding on hosts with different nutritional qualities was considered to be the only cause of mortality. The aim of this study was to determine the susceptible hosts to the pest. The initial population for each life table was 100 first larval instar on 20 cm foliage which continued to the end of adult longevity. For larval and adult feeding, the foliage was replaced regularly. Larval and adult mortality and eggs number per female were recorded on a daily basis. Results showed that the net reproductive rate (R₀) and intrinsic rate of increase (r_m) were higher on U. carpinifolia than the other hosts in both seasons. The net reproductive rate was less than one on Celtis caucasica in spring and on U. c. var. umbraculifera in summer, which represented the negative population growth on these hosts. Therefore, U. carpinifolia was the most susceptible host to Elm leaf beetle, the other susceptible hosts being U. glabra var. pendula and U. c. var. umbraculifera, in a descending order and Celtis caucasica was the least susceptible one. .

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Elm leaf beetle were reared under controlled conditions (25± 2 ^oC, 70± 5%R.H. and 16L: 8D) to determine relationship between biological traits and the number of eggs per female on different hosts and to evaluate correlation between traits. U. carpinifolia, U .c. var. umbraculifera, U. glabra var. pendula and Celtis caucasica were examined as hosts. The biological traits consisted of 1^st, 2^nd and 3^rd larval developmental times first, second, and third larval percent mortality rates prepupal and pupal developmental times male and female longevity and pre-ovipositional period recorded during experiments. The relationships between traits and the number of eggs per female were determined by multiple regression (Foreward selection and stepwise). The correlation between traits was evaluated, too. The results showed that the number of eggs per female were mostly affected by certain special traits such as 2^nd and 3^rd larval developmental time, pre-ovipositional period and male longevity which are distinct in different hosts and seasons.

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Greenhouse whitefly, Trialeurodes vaporariorum West., is one of the most important pests of field crops and ornamental plants in greenhouses which usually controlled by chemical insecticide and/or by biologic control factors. In this study the effect of singular and integrated use of Confidor and predator, Chrysoperla carnea (Steph.) against different nymphal instars of the pest on tomato plant was investigated. This experiment was carried out in 7 treatments, each in 3 replicates. Treatments included predator alone, the use of insecticide alone, and 4 integrated treatments of both the predator and insecticide. The predator was released at 5, 10, 15 and 20 day intervals after insecticide application. The control (water), insecticide spray and release of the predator were repeated each 10 days. In integrated treatments, insecticide was applied only once at the beginning of the experiment. The results showed that there was a significant difference between treatments. Pest control was not achieved with one or two attempts of release of predator or spray of insecticide. Pest elimination was only observed after third spray in insecticide treatment and 3 releases of predator beginning 20 days after spray in integrated treatment. These two treatments were shown to be of equal effectiveness in pest control. Also pest population was controlled after 5 releases which began 5 days after insecticide application. The use of the alone predator was statistically found to be less effective than treatment with the insecticide alone. Generally, integrated treatment is a promising alternative approach to pest control in longterm. It has clear advantages over chemical control in terms of pest resistance, environmental and general pest control issues. .

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Fecundity and sex ratio are the important factors in the quality control of parasitoid, Trichogramma. In this research, the effect of the host egg deprivation on these factors in Trichogramma brassicae Bezdenko was evaluated. The experiment was conducted with four treatments, each in five replications in a completely randomized design. Twenty mated females (24 h old) were transferred into the glass tubes (1.5×10 cm) separately and were fed by honey 20% daily. In one treatment, parasitoids were provided with the 150 host eggs (Sitotroga cerealella) in first day, but in other treatments the 150 host eggs were offered after 2, 4 and 6 days. In order to obtain fecundity, black eggs were counted after 3 or 4 days. After emergence, adult parasitoids were recognized as male and female by their antennae and sex ratio was obtained. Results indicated that as parasitoids, Trichogramma sp., were deprived from the host eggs longer, more decrease was observed in fecundity and female ratio. Therefore, parasitoid quality was decreased by the host egg deprivation.

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The predatory beetle Cybocephalus fodori minor has recently been reported in Iran. Also few studies have been reported on life cycle of Cybocephalus beetles, especially on that of C. f. minor. Thus, the life cycle and feeding rate of this predatory beetle was studied on pistachio oyster shell scale, Lepidosaphes pistaciae under laboratory conditions (temperature: 25 ± 2 °c relative humidity: 65 ± 5% and photoperiod: 16:8 L: D/h). Life cycle of C. f. minor was completed at six stages including egg, three larval instars, pupa and adult. Duration of the development for one generation (not considering preoviposition period) was 43-46 days for males and 38- 42 days for females. The developmental time length for the egg, larval instars1-3, pupa, male and female adults longevity, preoviposition and postoviposition periods was 8.8 ± 0.1, 5.2 ± 0.1, 34 ± 0.1, 6.8 ± 0.1, 17.3 ± 0.3, 59.2 ± 2.2, 65.8 ± 3.1, 6.8 ± 1.6 and 3.5 ± 0.5, respectively. Average fecundidity (number of eggs laid by a female per her life time) was 64.7 ± 6.2. Sex ratio in the laboratory and in the field was 1:1. Daily feeding rate for the female and male adults, larval instars feeding on adult female scale was 7.1 ± 3.5, 6.9 ± 2.2, 1.8 ± 0.2, 3.7 ± 0.2 and 5.9 ± 0.3, respectively. These parameters were also determined when those stages were fed on the eggs and second nymphal stages of pistachio oyster shell scale. Adult beetles over 60 days exhibited the highest feeding on this scale.

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Endophytic fungi, Neotyphodium spp. symbiotically infect host grasses, Fescue arundinacea Schreb. and F. pratensis Huds. and Mealybug, Phenococcus solani Ferris attacks some forage plants. To evaluate the role of these fungi to control this pest, four genotypes of F. arundinacea and two genotypes of F. pratensis were used. Plant tillers were split into two sections, one section of which was freed from endophyte using a fungicide mixture. The mixture contained 2 grams of active ingredients of Propiconazol and 1 ml of Folicur per liter of water. New tillers from endophyte-infected and endophyte-free plants were transferred into the field. The number of mealybugs was measured after the first visible sign of infestation on roots. To count mealybug, one plant hill of each plot was randomly selected. Hay yield of each plot was measured by clipping the plants 5 cm above ground level. Correlation of hay yield and other growth characteristics with the number of mealybugs on roots as an index for mealybug damage on infested plants was determined. The results indicated that endophyte-free plants were highly infested with mealybug, P. solani compared with endophyte-infected plants that were completely free of P. solani, correlation coefficients showed that there was significant negative correlation between forage yield and mealybug numbers, indicating mealybug damage on infested plants. It seems that endophytic fungi are effective biocontrol factors for some root feeding pest such as mealybug, P. solani.

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Canola (Brassica napus) is one of the important oil seed crops cultivated in many parts of Iran. One of the main problems of seed production of canola is pollination and fertilization of flowers. Insects are the major pollinators. In order to study the fauna of insect pollinators of 3 cultivars of canola including Talaye, Okapi and S.L.M. and the difference between the attractiveness of these cultivars to insects during the flowering period, insects were collected by sweeping net and identified. Their abundance was determined at different periods of time during a day. Results showed that insect pollinators belonged to five orders and 18 families. The most abundant pollinators were Hymenopterous insects specialy honey bees (Apis mellifera) which were about 50%. Irrespective of Apis mellifera, the most abundant insects captured belonged to Diptera. Three Dipterous insects, Bibio hortulanus, Metasyrphus corollae and Platypalpus sp. were collected and identified. During the flowering period (March to mid April) in Isfahan, honey bees were more abundant in the warmer hours of the day, mostly noon and afternoon, but were less active in the early hours of the day, morning, because of cold weather and low nectar production. Honey bees were more active than other pollinators on Talaye at 9 a.m. and on Okapi at mid-day, noon, and during afternoon. Results also showed that insect pollinators could increase seed yield by 53%.

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Pollination and fertilization of canola flowers are the main factors of canola seed production. In order to study the effects of insect pollinators on seed quantity and quality of three chosen cultivars of canola, namly, S.L.M., Okapi and Talaye, a split plot experiment in a complete randomized block design with four replications was carried out in Isfahan region. Main plots consisted of canola cultivars, and subplots consisted of open pollination and non-pollination by insects. Results indicated that the time to seed ripening in pollinated plots was 10.5 days less than those of non-pollinated plots. Pollination by insects increased the number of pods per plant, number of seeds per pod and weight of 1000 seeds, by 14.3%, 23.5% and 10%, respectively. Grain yield also increased by 53% in pollinated plots. Pollination decreased seed moisture percentage by 3.15%, but its effect on seed oil percentage and germination percentage were not significant. Time to seed germination of plants of pollinated plots decreased three hours. Cultivars were significantly different in seed oil percentage and time to seed germination. Talaye cultivar produced the highest amount of oil (45.5%), while Okapi produced the lowest (40.8%). There were significant interactions between cultivars and pollination in terms of seed ripening, oil percentage and moisture of seeds, and the effects of pollination was different in different cultivars.

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Sarta longhorned beetle, Aeolesthes sarta, is one of the most destructive wood borer pests of fruit and shade trees in Iran. In this research, the reproductive parameters were studied under laboratory conditions. Fifteen pairs of newly developed adults (1-2 days after emergence from overwintering sites) were caged separately on 15 logs of Ulmus carpinifolia and fertility table was made using this data. The results showed that 3.9±0.2 days after emergence, females began to oviposit for 16.6±0.6 days, as oviposition period. Mean number of laid eggs was 122.6±17.5 per female. The mean longevity of male and female was 26±0.6 and 29.4±0.4 days, respectively. Females had no mortality during oviposition period, so gross reproductive rate (GRR) and net reproductive rate (R₀) (famale/female/generation) were equal (61.6±8.7). Intrinsic rate of increase (r_m), mean generation time (T) and doubling time of the population (t) were 0.0067±0.24^-5 famale/female/day, 612.5±0.4 and 102.7±3.6 days, respectively. The finite rate of increase (λ) (female/female/day) was 1.006±0.24^-5. Intrinsic rate of increase (r_m) was very low (0.00672), because of longer lifetime of females (mean 602 days), low longevity during reproductive period (maximum 22 days) and long mean generation time (612.5 days).