Journal of Basic and Applied Sciences  -   Volume 8 Number 2

 

Impact of Release Intervals and Densities of Trichogramma chilonis (Ishii) (Hymenoptera: Trichogrammatidae) Against the Sugarcane Stem Borer, Chilo infuscatellus (Lepidoptera; Pyralidae) under Field Conditions

Raza Muhammad, Maqsood Anwar Rustamani, Nazia Suleman, Nazir Ahmad and Qadeer Ahmad

http://dx.doi.org/10.6000/1927-5129.2012.08.02.36

Abstract: The parasitization of Trichogramma chilonis parasitoids was found higher in the blocks where parasitoids were released to control Chilo infuscatellus at weekly interval (52.4 %) as compared to fortnight (40.9%) and monthly intervals (32.7%). Mean parasitization was (42.7%) when 80,000 thousand parasitoids were released on monthly basis followed by 41.4% (40,000), 37.8% (20,000) and 34.0% (10,000). However the mean infestation was below economic threshold levels ranging from 5.3 to 6.5 % in all the blocks where the parasitoids were released in variable numbers.

Keywords: Sugarcane, Trichogramma chilonis, Chilo infuscatellus, release interval, release densities.

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The Effect of Grain Size on Radon Exhalation Rate in Soil Samples of Dera Ismail Khan in Pakistan

Tabassum Nasir and Nisar Ahmad

http://dx.doi.org/10.6000/1927-5129.2012.08.02.29

Abstract: Radon concentration and its exhalation rate has been measured from twenty five soil samples collected from seven different locations of Dera Ismail Khan, in the north west of Pakistan. These samples were crushed after drying and passed through sieves with different sizes of pores to get three grain sizes, £0.595 mm, 0.595-2.00 mm and 2.00-4.00 mm of soil. CR-39 based NRPB (National Radiological Protection Board) radon dosimeters have been used to measure the radon concentration and exhalation rates. The maximum average value of radon exhalation rate has found to be: (3.57±0.38) Bq m-2 hr-1 in the samples having grain size 2.00-4.00 mm and the minimum as: (2.21±0.26) Bq m-2 hr-1, in the samples with grain size £ 0.0595 mm. This indicates that the radon exhalation rate increases with the grain size. The maximum average value of radon exhalation rate has been found in samples collected from river side where soil texture is silty clay loam. The obtained values of radon exhalation rate for all the samples are well below the world average value of 57.60 Bq m-2 hr-1.

Keywords: Radon concentration, Radon exhalation rate, grain size, soil texture.

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