Journal of Basic and Applied Sciences  -   Volume 8 Number 2

Effect of Different Photo Periods on the Biological Parameters of Chrysoperla carnea under Laboratory Conditions
Qadeer Ahmed, Raza Muhammad, Nazir Ahmad, Javed Ahmed, Shahnaz Naz, Hayder Ali and Nazia Suleman

http://dx.doi.org/10.6000/1927-5129.2012.08.02.61

Abstract: Many insects are known to give response in adaptive way for seasonal changes in day lengths. Photoperiod control’s many developmental responses and allows insects to survive periods of unfavorable environmental conditions. An experiment was conducted to study the effect of different photoperiod lengths on biological parameters of green lacewing, Chrysoperla carnea. Four different photoperiod regimes were selected with varying lengths of light/dark hours (8/16, 10/14, 24/0 and 0/24) at a constant 26±2°C temperature with 70 % RH (relative humidity) in the laboratory. Photoperiod regimes affected the development of C. carnea from egg to adult. In complete darkness (L: 0 D: 24), minimum egg laying, hatching, larval survival and adult emergence were recorded. Incubation period for eggs, larval period and pupal duration were also significantly longer in complete darkness as compared to other treatments 8L: 16D and 10L: 14D. Whereas, the treatment with complete light hours (L: 24, D: 0) resulted in maximum egg laying hatching, larval survival and adult emergence. The incubation period for eggs, larval and pupal duration significantly shortened as compared to other treatments.Sex ratios skewed towards female when full light hours were provided for development.

Keywords: Chrysoperla carnea, photoperiod regimes, hatching, larval survival, sex ratios.

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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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