| The Pugionium cornutum belongs to the family Cruciferous, the Pugionium was live in two year, it is endemic species of China. It is a kind of wild vegetables and medicinal plant that our country developed newly in recent years. The Arthropod communities were studied systematicly in Pugionium cornutum field in from 2003 to 2004, and used life table to research their biological characters of the dominant species Plutella xylostella, the results were as follows:(1) Through the systematic investigation about Arthropod communities of the natural field and medicines field. 10155 specimens were collected in the natural field, which belonging to 2 phylums, 4 classes, 16 orders, 47 families, 78 species. 8274 specimens were collected in the medicines field, which belonging to 2 phylums, 4 classes, 16 orders, 33 families, 62 species. Richness, diversity, evenness etc. of natural field community was greater in the natural field than the medicines field, fluctuate smaller in the time array, community's stability was strong; Richness, diversity, evenness etc. of the medicines field, fluctuating greatly in the time array, the stability was fragile. Using the optimal sorting, the natural field in one year period was divided into 4 stages and the medicines field was divided into 5 stages. There were own development and change characters on different stage of two fields, natural field community structure steady was higher than the medicine field obviously.(2) Compare to alternative of laying eggs on Pugionium. cornutum, Brassicae campestris, B. napus and B. oleraceaas. The result showed that the alternative order of lay eggs was P. cornutum ≥ B. campestris > B. napus > B. oleracea. The rate of lay eggs was more 9 times on P. cornutum than B. oleracea.(3) The life table of P. xylostella on P. cornutum was studied at the constant temperature 24℃ in laboratory. The results were as follow: ①The net reproductive rate (Ro) of 76.30, the mean generation time (T) of 23.25 day, the intrinsic increase rate (r_m) of 0.19, the finite increase rate ( λ) of 1.20, the doubling time (t) of 3.72 day, the instantaneous birth rate (b) of 0.23 and the instantaneous death rate (d ) of 0.05. ② In age distribution of constant population, the immature period was 96.9% and the mature period was 3.04%.(4) Compared with life table of nature population and life table of lab population. Population trend index of the lab population was 77.45, and the total survival rate of generation was 0.41; Population trend index of the nature population was 28.98, and the total survival rate of generation was 0.15. Control index (EIPC) of "pray on and other " was the biggest in the nature filed, it was 6.99, Secondly was the parasitic, the control index (EIPC) was 3.44.(5) To feed the P. xylostella on P. cornutum, B. campestris, B. napus and B. oleraceaas 4 Cruciferous vegetables, the population trend index of P. xylostella showed as B. oleraceaas>B. campestris>B. napus>P. comutum; But the total survival rate is shown as B. campestris>B. oleraceaas>B. napus>P. cornutum.(6) The population trend index under different temperature was showed as 24 t>27 T>2] V> 30 X: >18 "C,The total survival rate was showed as 24 T>27 T>21 TC>30 V >18 *C too.(7) Development threshold temperature of P. xylostella was 9.85 "C, and the effective accumulated temperature was 259.41 day degrees. It took place 6-7 generations in one year of Ningxia, and it took place 3-4 generations in growth period of P. cornutum. And the hatching of egg, the adults hatching and the mating behavior has been described with carefully.
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