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Sipha maydis (Passerini) is a pest of Poaceae in many cereal-growing area of the world and Iran. The effects of temperature on biology and life table were investigated at five constant temperatures (15, 20, 25, 30 and 32.5±1°C), 60±5% relative humidity (RH) and a photoperiod of 16L : 8D h. The results indicated that aphids failed to complete development at 32.5°C. Developmental time was ranged between 17.28 to 9.55 days at 15 and 30°C, respectively. The lower developmental threshold (T0) and thermal constant of S. maydis were estimated to be –5.52°C and 332.22 degree-days, respectively. The Analytis-3/Briere-1 model (as non linear model) is highly recommended for the description of temperature dependent development of S. maydis. The highest life expectancy of adults at emergence was 33.35 days at 20°C. The mean adult longevity of females and nymphipositional period were the highest at 20°C. The mean lifetime fecundity at 15, 20, 25 and 30°C were 21.24±1.97, 44.82±3.18, 22.25±2.33 and 16.39±1.15 nymphs/female, respectively. The survivorship curves of S. maydis were type I at 20 and 25°C (H < 0.5) and type III at 15 and 30°C (H > 0.5). The highest and lowest values of intrinsic rate of increase (rm) were observed at 20 (0.173±0.012 females/female/day) and 15°C (0.109±0.003 females/female/ /day), respectively. The growth index (GI) at 15, 20, 25 and 30°C were 0.033, 0.069, 0.062 and 0.038, respectively. According to this research the optimum temperature for population growth of S. maydis was 20°C. Our findings provide fundamental information and when this information is used in association with other ecological data, it may be valuable in development and implementation of management programs of S. maydis.
A new species, Caesarodispus shandizensis sp. nov. (Acari: Heterostigmatina: Microdispidae) associated with ants of the genus Temnothorax Mayr (Hymenoptera: Formicidae) from northeastern Iran is described. We also found Caesarodispus minutus (Sevastianov, 1981) associated with Temnothorax sp. These findings provide a new association between the mite genus Caesarodispus and ants of the genus Temnothorax. A key to world species of the genus Caesarodispus is provided and the host range of the mite genus is reviewed, showing that all ant hosts of the mite genus belong to the subfamily Myrmicinae (Hymenoptera: Formicidae).
The temperature-dependent development of Hemiptarsenus zilahisebessi Erdös (Hymenoptera: Eulophidae), a biological control agent of Liriomyza sativae Blanchard (Diptera: Agromyzidae), was studied in the laboratory at seven constant temperatures (10°C, 15°C, 20°C, 25°C, 30°C, 35°C, and 40°C) with a relative humidity of 65% and a photoperiod of 16L:8D h.. The total developmental time (egg to adult) decreased significantly with increasing temperature, and there was no development at 10°C or at 40°C. Linear and nonlinear models were used to describe the relationship between developmental rate (1/days) and temperature (°C), and to determine developmental thresholds. Using a linear model, the lower temperature threshold (zero development) was estimated to be 8.94°C for males and 9.02°C for females, and the thermal constant (K) was 147.1 degree-days (DD) for males and 156.3 DD for females. Among the nonlinear models examined, the Briere-1 and Briere-2 models were accepted on the basis of goodness-of-fit to the data (residual sum of squares and coefficient of determination) and estimable temperature thresholds (T0, Topt and Tmax). These models gave the best description of the temperature-dependent development of H. zilahisebessi. Temperature-based development models can be useful in designing massrearing protocols, in helping to make decisions in augmentative release trials, and in the development of predictive modelling.
The temperature dependent biology of greenbug, Schizaphis graminum Rondani on Kavir barley cultivar was studied at seven constant temperatures including 10, 15, 19, 22, 26, 31, and 33±1°C, 70% relative humidity (RH), and a photoperiod of 16:8 (L:D) hours. The period of immature development ranged between 6.60 days at 26°C to 28.56 days at 10°C, respectively. All tested aphids failed to develop at 33°C. The calculated rm and λ values were significantly the highest at 26°C and lowest at 10°C, respectively. The mean generation time and doubling time of S. graminum decreased linearly by increasing the temperature from 10 to 26°C. Additionally, the total number of offsprings per female was extremely low at 10 and 31°C, contrary to the highest and lowest values of life expectancy at 10°C (41.73 days) and 31°C (7.66 days), respectively. The results of the present study revealed that temperature had great effects on biology of S. graminum, which was never previously studied on barley in Iran.
Mirax caspiana sp. nov. from Iran is described and illustrated. The new species is characterized by having the second metasomal tergite aciculate, the width of face 1.2 times longer than height of face and clypeus combined, the penultimate flagellomere twice as long as wide and the malar space as long as basal width of mandible. A key to the species of the genus Mirax Haliday in the West Palaearctic Region is provided.
Genetically manipulated food barley, Hordeum vulgare L. var. valfajr, was compared to commercial-grade starch as carbon sources in groundnut and soybean based media for supporting growth, sporulation and delta-endotoxin production by Bacillus thuringiensis Berliner B. thuringiensis kurstaki HD-1 and a promising newly isolated B. thuringiensis strain (referred to as BTA) were used. MgCl2, CaCl2, and MnCl2 were used as trace-elements. Culture media were compared in shaken flasks and then in 5 l Fermentors. Biomass, delta-endotoxin levels and the number of spores as colony forming units (CFU) were evaluated. For each of the two strains, biomass and delta-endotoxin synthesis were not significantly different in soybean-based media after substitution starch by barley flour. There were significant differences between the two strains with respect to biomass and toxin production. Evaluated costs of media preparation showed that food barley is an economical alternative to commercial-grade starch in the production of BTA bioinsecticide.
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