Trends of precipitation extreme indices over a subtropical semi-arid area using PERSIANN-CDR

In this study, satellite-based daily precipitation estimation data from precipitation estimation from remotely sensed information using artificial neural networks (PERSIANN)-climate data record (CDR) are being evaluated in Iran. This dataset (0.25°, daily), which covers over three decades of continuous observation beginning in 1983, is evaluated using rain-gauge data for the period of 1998–2007. In addition to categorical statistics and mean annual amount and number of rainy days, ten standard extreme indices were calculated to observe the behavior of daily extremes. The results show that PERSIANN-CDR exhibits reasonable performance associated with the probability of detection and false-alarm ratio, but it overestimates precipitation in the area. Although PERSIANN-CDR mostly underestimates extreme indices, it shows relatively high correlations (between 0.6316–0.7797) for intensity indices. PERSIANN-CDR data are also used to calculate the trend in annual amounts of precipitation, the number of rainy days, and precipitation extremes over Iran covering the period of 1983–2012. Our analysis shows that, although annual precipitation decreased in the western and eastern regions of Iran, the annual number of rainy days increased in the northern and northwestern areas. Statistically significant negative trends are identified in the 90th percentile daily precipitation, as well as the mean daily precipitation from wet days in the northern part of the study area. The positive trends of the maximum annual number of consecutive dry days in the eastern regions indicate that the dry periods became longer in these arid areas

Effect of four powdered spices as repellents against adults of Rhyzopertha dominica (F.), Sitophilus granarius (L.) and Tribolium castaneum (Herbst) in laboratory conditions

Studies were conducted to test the repellency of four powdered spices, black pepper (Piper nigrum.), chili pepper (Capsicum annuum), cinnamon (Cinnamomum aromaticum) and turmeric (Curcuma longa), against three stored-product insects, the lesser grain borer, Rhyzopertha dominica, the granary weevil, Sitophilus granarius and the red flour beetle, Tribolium castaneum. The cup bioassay technique was used, to determine the response of insects to potential repellents by measuring their movement from treated grain. The device is made of galvanized screening with 2 mm perforations shaped into a cylinder of 6 cm diameter and 15 cm high, with a mesh bottom, and is placed in the centre portion of plastic container of 15 cm diameter and 15 cm high. The powdered spices were poured into 200 g of wheat mass by a long-stemmed funnel at concentrations of 0, 0.25, 0.75, 1.5 and 2.5% on (w/w) basis. Twenty adults of three species are released into the centre of the grain mass in the container through a long-stemmed funnel. The experiments were conducted at room conditions. The number of trapped insects was determined at 3 different intervals after the introduction of the insects. Results showed that all tested plant powders had repellent activity against the three stored-product insects. Adults of S. granarius repelled faster, followed by T. castaneum and R. dominica. At the highest concentrations and intervals, wheat grains treated with cinnamon powder were the most repellent to adults of S. granarius (up to 92.5% after 1 h), followed by chili pepper treatment for T. castaneum (up to 72.5% after 6 h) and black pepper treatment for R. dominica(up to 58.75% after 24 h).Keywords: Repellency, Spices, Rhyzopertha dominica, Sitophilus granarius, Tribolium castaneu

A comparative study on the functional response of Wolbachia-infected and uninfected forms of the parasitoid wasp Trichogramma brassicae

Trichogramma species (Hymenoptera: Trichogrammatidae) are haplo-diploid egg parasitoids that are frequently used as biological control agents against lepidopteran pests. These wasps display two reproductive modes, including arrhenotoky (bisexuality) and thelytoky (unisexuality). Thelytokous forms are often associated with the presence of endosymbiotic Wolbachia bacteria. The use of thelytokous wasps has long been considered as a way to enhance the efficacy of biological control. The present study investigates the potential of a thelytokous Wolbachiainfected and an arrhenotokous uninfected Trichogramma brassicae Bezdenko strain as inundative biocontrol agents by evaluating their functional response towards different egg densities of the factitious host, the Angoumois grain moth, Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae). The results revealed a type II functional response for both strains in which parasitism efficiency decreases with host egg density because of an increasing host handling time. A model with an indicator variable was used to compare the parameters of Holling’s disc equation in different data sets. It was demonstrated that the two strains did not differ in host attack rate. However, the Wolbachia-infected strain did have an increased host handling time when compared to the bisexual strain. Some applied aspects of the findings are discusse

A Review of Global Precipitation Data Sets: Data Sources, Estimation, and Intercomparisons

In this paper, we present a comprehensive review of the data sources and estimation methods of 30 currently available global precipitation data sets, including gauge-based, satellite-related, and reanalysis data sets. We analyzed the discrepancies between the data sets from daily to annual timescales and found large differences in both the magnitude and the variability of precipitation estimates. The magnitude of annual precipitation estimates over global land deviated by as much as 300 mm/yr among the products. Reanalysis data sets had a larger degree of variability than the other types of data sets. The degree of variability in precipitation estimates also varied by region. Large differences in annual and seasonal estimates were found in tropical oceans, complex mountain areas, northern Africa, and some high-latitude regions. Overall, the variability associated with extreme precipitation estimates was slightly greater at lower latitudes than at higher latitudes. The reliability of precipitation data sets is mainly limited by the number and spatial coverage of surface stations, the satellite algorithms, and the data assimilation models. The inconsistencies described limit the capability of the products for climate monitoring, attribution, and model validation

A floristic study of the Sorkhankol Wildlife Refuge, Guilan province, Iran

Sorkhankol Wildlife Refuge with an area of 1209 ha is located in the central part of Anzali Wetland. In total, 81 species belonging to 35 families and 68 genera were surveyed and identified on the basis of a floristic study from July 2013 through June 2014. The largest families are Poaceae (11 taxa), Asteraceae (8 taxa) Apiaceae, Brassicaceae and Cyperacae (5 taxa). The dominant life forms were cryptophyte (43.21%), followed by the therophytes (39.51%), hemicryptophytes (13.58%) and phanerophytes (3.7%). From the chorological point of view, the largest proportion of the flora belongs to the pluriregional elements (44.44%). A comparison between our study and other parts of the Anzali Wetland showed that Sorkhankol was not particularly species-rich. Currently, the major threats to the research area include eutrophication, pressure from boating and fishing activities, invasion of exotic species and other human induced disturbances

Effect of single and mixed diets on the fitness of omnivorous thrips, Thrips tabaci (Thys.: Thripidae)

Abstract Food choice in omnivorous animals is influenced by the balance of nutritional needs, food availability, and quality of a particular food items. Here, we study whether omnivorous onion thrips, Thrips tabaci Lindeman, feed on the eggs of its competitor Tetranychus urticae Koch (Acari: Tetranychidae) when an alternative supplemental source is, or is not, available. Thrips were either fed a cucumber leaf alone, or this diet was supplemented with pollen, mite eggs, or both. We demonstrated that the supplemental food sources improved several fitness-determining traits of thrips with pollen, being nutritionally superior to mite eggs. Pollen reduced the development time and increased the population growth of thrips compared to mite eggs. When both pollen and mite eggs were available, thrips fed on both; pollen to improve nutritional status and eggs to eliminate the opponent, despite the latter's consisting lower of nutritional benefit. In all, this study showed that omnivorous thrips benefit from a cucumber leaf diet that is supplemented with other food sources and that pollen and mite eggs increase several fitness traitsand positively affect the dynamics of future thrips generations

Effect of single and mixed diets on the fitness of omnivorous thrips, Thrips tabaci (Thys.: Thripidae)

Food choice in omnivorous animals is influenced by the balance of nutritional needs, food availability, and quality of a particular food items. Here, we study whether omnivorous onion thrips, Thrips tabaci Lindeman, feed on the eggs of its competitor Tetranychus urticae Koch (Acari: Tetranychidae) when an alternative supplemental source is, or is not, available. Thrips were either fed a cucumber leaf alone, or this diet was supplemented with pollen, mite eggs, or both. We demonstrated that the supplemental food sources improved several fitness-determining traits of thrips with pollen, being nutritionally superior to mite eggs. Pollen reduced the development time and increased the population growth of thrips compared to mite eggs. When both pollen and mite eggs were available, thrips fed on both; pollen to improve nutritional status and eggs to eliminate the opponent, despite the latterâs consisting lower of nutritional benefit. In all, this study showed that omnivorous thrips benefit from a cucumber leaf diet that is supplemented with other food sources and that pollen and mite eggs increase several fitness traits and positively affect the dynamics of future thrips generations

Photoperiod Effect on Fecundity, Longevity and Sex ratio of Trichogramma brassicae (Hym: Trichogrammatidae)

The effect of photoperiod on parasitization of the eggs of Ephestia kuehniella Zeller (Lep: Pyralidae) by Trichogramma brassicae Bezdenko (Hym: Trichogrammatidae) was investigated under several photoperiodic regimes of L: D = 0: 24, 3: 21, 6: 18, 9: 15, 12: 12, 15: 9, 18: 6, 21: 3 and absolute light on. Fecundity of T. brassicae females (the number of parasitized E. kuehniella eggs) was independent of photoperiod in the whole life time of females. However, photoperiod had a significant influence on the longevity of T. brassicae females. The least fecundity and longevity was for those that developed and were kept under 18L: 6D and the highest fecundity and longevity was for those that developed and were kept under 21L: 3D and absolute darkness, respectively. On the other hand, the proportion of T. brassicae females was dependent of photoperiod and the highest proportion of females was observed under 18L: 6D. It seems that long term photoperiods may stimulate a particular gland to secret a special hormone which results in more longevity and female proportion of parasitoid. As a conclusion, long term photoperiods may improve efficiency of the parasitoid by increasing longevity and sex ratio