دراسة دينامية الجماعة السكانية و الإنتاج الثانوي لمتشابهة الأقدام الأرضية النوع Porcellio spinicornis Say, 1818 في منطقة الجادرية- بغداد- العراق

Abstract EN

The Present study includes the study of the population dynamic and secondary production of species Porcellio spinicornis in AL- Jadiriya region in Baghdad.

Monthly samples have been taken by using a quadrate 0.0625 m2 from November 2007 to November 2008.Soil temperature, PH, Soil salinity relative humidity and organic matter contents of the Soil samples have been determined during the study period.

The results have been shown that these parameters ranged between 7-38C0, 7.5 -8.3, 1.5- 2.6 part per thousand, 18- 58 % and 0.3- 3.1 % respectively.

The soil texture of the studied area was consisted of 36.8 % sand, 16.4 % silt and 46.3 % clay.

The population density of P.

spinicornis, ranged from 891 ind/m2 in May 2008 to 148 ind/m2 in January 2008.

This species have been shown high aggregation dispersion in the study area.

The sex ratio have been shown that the number of females was more than that of males and significantly different P < 0.05 during the reproductive months.

Furthermore, it was found that the juveniles of species were present at most time of the year, But the large sized groups have been observed during summer and spring.

And showed a positive linear correlations between the size of ovigerous females and the number of eggs and The incubation period ranged from 25 to 32 day in this species, The number of eggs per brood ranged between14- 82 egg in this species.

The cohort analysis of the populations have been shown that P.

spinicornis had four generations during the study period .The life table analysis results have been shown that the expected life for this species was seven months.

And this species had two breeding season (spring and autumn), and a high growth rates was recorded in spring and summer .The total rates of biomass for this species was 4183.03 mg/m2 dry weight per year .And the secondary production for this species was 478.38 mg/m2 dry weight per year, while the (P/B) for this species was 1.1.