JWSS - Journal of Water and Soil Science

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Evaluation of uric acid contents of poultry excreta was examined for use in the estimation of apparent protein digestibility. Uric acid was determined either by high-performance liquid chromatography or by spectrophotometric method. A high-pressure liquid chromatographic assay was used with absorbance measured at 285 nm. The method used a reverse-phase system with a C18-bonded column (250*4.6 mm, i.d.). The mobile phase was distilled deionized water. Injection volume was 20 l with a flow rate of 1 ml/min. Correlation (r) between the two methods for uric acid content of excreta from birds fed diets with different methionine levels was 0.976. The uric acid values were then used to determine apparent protein digestibility. The apparent protein digestibility values, when corrected for uric acid nitrogen, were comparable with those calculated from amino acid analysis.

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Populations of Arboridia kermanshah Dlabola is increasing in Isfahan vineyards. In this study, some morphological characteristics of the immature stages, over wintering sites, number of generations per year, and seasonal population fluctuations of this pest were studied in vineyards in Isfahan Province. Eggs showed apparently four distinct embryonic developmental stages. At 25.8 ±2˚C, development of eggs was completed in 10.9 ± 0.7 days. There were five nymphal developmental stages. Nymphal stages can be distinguished with wing pad development and width of head capsule and width of pronotum. The grape leafhopper overwintered as adults under leaves and crop residues. Rearing studies showed that the grape leafhopper had three generations per year, each lasting 33.9±0.6 (without overwintering period), 46.3±0.7 and 37.3±0.6 days, respectively. Seasonal monitoring of adults, nymphs and eggs showed three or four overlapping periods of activity in the field. Four periods of activities of adults were recorded through season from early May – mid June, mid June – mid July, mid July - late August and early September – mid October.

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Some bioecological aspects of grape leafhopper, Arboridia kermanshah Dlabola, including: the egg distribution under the leaf surface, eggs and nymphs spatial distribution on the vine arms, the adult distribution on three strata of the vine canopy, the adult diel activities and the geographical distribution of this species in Isfahan province were studied. Samplings were done in the 1997. The egg distribution under the leaf surface was determined by repeated sampling during the season and the egg density was estimated on three regions such as the main and secondary vein, the leaf surface margins and others. Eggs and nymphs spatial distribution along the vine arms were studied weekly for six weeks by sampling an arm of five vines during the second generation, the leafhopper population was the highest. The adult spatial distribution on the vine canopy was determined by sampling three strata of the vine canopy using the D-vac apparatus. Diel activities were studied by sweeping nets fifty times per vineyard at the two hour intervals from 8 a.m. to 20 p.m. Temperature and the relative humidity were also measured in the shade once per hour. The presence and the abundance of this species in 87 vineyards in the different climatic conditions were studied by a sweeping net. The leaf margin and around of the secondary vein were preferred for the oviposition of the leafhopper. Adults, nymphs and eggs were more abundant in the middle strata of the vine canopy than others. The mean pattern of the daily activity of the adult indicated one peak at 8 a.m. and the other one at 20 p.m. Maximum temperature thereshold for the adult activities was 28º C. The study of the grape leafhopper distribution in isfahan province indicated that this species was distributed in the most vineyards, but was highly abundant in more humid conditions.

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In 1997, in two vineyards of Isfahan university of technology and Zobeahan in Isfahan, the density fluctuations of Arboridia kermanshah Dlabola and their injury symptoms were studied. In each vineyard three leaves of each of ten randomly selected vines were sampled weekly. Nymphs in different instars were counted directly and rate of injury symptom (leaf discoloration) was determined with planimeter. Special cages were used to determine rate of injury symptom for each nymphal instar in comparison to each other. Rate of injury symptoms and nymphal density indicated two peaks through growing season until harvest. Tolerance threshold for A. kermanshah nymphs was determined 80 first instar nymphal days or presence of 11-12 first instar nymphs and feeding for seven days. With increase of nymph densities, damage symptom increased rapidly.

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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).

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  Aphids are known as important pests of plants specially almond trees. Seasonal population fluctuation of two aphid species, Brachycaudus amygdalinus (Schout.) and Hyalopterus amygdali (Blanch.) were studied in 1999-2000 on almond trees in Najafabad area. Characteristics such as times of egg hatch, appearance, outbreak, spring migration to alternative hosts, migration from alternative hosts in fall, oviposition, number of eggs laid, damage degree, alternative, other primary hosts and some natural enemies were investigated. In early spring damage signs of B. amygdalinus were expressed on almond twigs as serious leaf curling followed by retarded growth of twigs and shortened internodes. Shortly after that H. amygdali colonized other leaves. For both species egg hatching was coincided in late winter however colonization and population increase of H. amygdalei were observed two weeks later than what was observed for B. amygdalinus. With the onset of warm season, both species moved from almonds to alternative hosts for aestivation. Gynoparae shortly followed by males appeared on alternative hosts in late summer and migrated to almonds. Oviparae produced by gynoparae mated with males and laid their eggs near the buds.

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Due to injuries of pesticides to natural enemies of pests and pollinator insects, especially honeybees, during the flowering periods, it is essential to protect them. Application of chemical compounds along with the pesticides on the plants could repel the non-target insects from the sprayed areas for sometime and lessen the hazards of pesticides to them. In this study, ten repellent chemicals whose repellency effect was proven in the laboratory in previous studies were screened in the field. Among tested repellents including, Acetophenon, Methyl ethyl ketone, Methyl isobutyl ketone, Cyclohexanone, Acetyl acetone, Methylsalicylate, Propionic anhydride, Maleic anhydrate, 2- Ethylhexylamine, and Dibutylamine, it was revealed that amino group compounds including 2- Ethylhexylamine and Dibutylamine and esteric compound, Methylsalicilate had the highest repellency effect on the honeybees under the field conditions. Repellency effect of these compounds was greater at 15 pm than other sampling times. Repellency effects of different concentrations of these three compounds, when mixed with 0.5% concentration of fixative compounds, showed that the mixture of 2- Ethylhexylamine with Benzylbenzoate, Dibutylphthalate and Benzylalcohole with concentration of 0.17, 0.4 and 0.03 % respectively, the mixture of Dibutylamine at the concentration of 1% with Benzylbenzoate and Dibutylphthalate and at the concentration of 0.08% and higher with Benzylalcohole, and also mixture of Methylsalicilate at the concentration of 1.8 % and higher with Benzylalcohole, all have repellency effect of more than 70% under the field conditions.

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Safflower having oil with high unsaturated fatty acids is a very valuable plant. However the sensitivity of safflower to some pests as safflower fly (Acanthiophilus helianthi), particularly in drought stress conditions has limited its production. In order to evaluate the effect of drought stress on population density and damage of important safflower pests, especially safflower fly, an experiment was conducted in the field using 5 irrigation treatments including 50, 70, 90, 110 and 130 mm evaporation from class A pan in a randomized complete block design with three replications. The local safflower variety used in this study was Isfahan land variety, Kooseh. In each irrigation regime, the half of one plot was locally sprayed by Chlorpyrifos in 2ml per liter of water to be compared with non-sprayed part. During 8 weeks of sampling, population of aphids, Uroleucon carthami, leafhopper, Empoasca decipiens and safflower fly, A. helianthi and also percentage of damaged heads by safflower fly were measured. The results showed that in non-sprayed conditions, the highest safflower fly (2.38 flies per net) and aphid population (165.57 aphids per plant) was observed at 130 mm evaporation regime. Drought stress also decreased (30.23 %) safflower seed yield. Severe drought stress together with non-spaying may increase safflower pests population particularly safflower fly and reduce seed yield. However low level of drought stress (70 mm evaporation from class A pan) may decrease relative number of insects and save irrigation water. Drought stress also decrease the population of leafhopper. In this study, 70 mm evaporation regime was the optimum irrigation treatment regarding lower aphid and fly damage (15.86% damaged heads in non-sprayed condition) and higher safflower seed yield (1687.5 kg/ha in sprayed condition).

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