The Effect Of Long-term Combined Stress Of Cadmium And Zinc On The Population Ecosystem Of Sitobion Avenae(Hemiptera:Aphididae)

Environmental pollution leads the accumulation of heavy metals in the soil—plant—insect system, which destroyed the agroecologicalsystem and induced the unprecedented selective pressure. Effect of a single heavy metal stress on the Sitobion avenae(Fabricius) hasbeen studied in the previous researchers, andthe results showed that heavy metal could influence the growth and development and reproduction, however,there are almost combined stress of multiple heavy metal elements in the environment. In order to explore the combined stress of cadmium and zinc on the growth and development and fecundity of S. avenae, and the accumulation effect through the soil—plant—S. avenaesystem.The atomic absorption spectrometer was used to measure the content of cadmium and zinc in wheat and S. avenae at 1、6、11 generations, age-specific life table was established to evaluate the life table parameters of S.avenaeat 1、3、5、10 generations.Therefore, the exploration about combined stress of multiple heavy metal to S.avenae has provided the theory basis to the ecology genetics and evolution of insectThe result showed that :1.The content of Cd in wheat increased firstly,then it decreased with the increasing of Zn in soil, and Cd was transferred mostly at 800 mg/kg,but the content of Cd has no significant difference with controlat 1600mg/kg.2.Contrast with single Zn treating, the concent of Zn in wheat was only enhanced at1600mg/kg,others different contents of Cd and Zn inhibited the transfer of Zn to the wheat.3. The element Cd 、 Zn and the interaction effect all influenced the growth and development of S. avenae significantly, and Zn showed the maximum effect to S.avenae.4.The interaction of Cd and Zn performed higher effect on the net rate of increase(R0)of S.avenaethan the singleCd stress, and thevalue of net rate of increase(R0) was biggest at5 th,Cd and Zn had no significant effect on the mean generation time(T) of S. avenae at different generations.5.The age-specific survival rate(lx), age-specific fecundity(mx), and age-specific maternity(lxmx) of S.avenaeat the 1th、3 th、5 th generations all high than the 10 th, the area oftheage-specific maternity(lxmx)was most significant with the interaction of differentcontent Cd and 400 mg/kgZn.From the results of the study draws the following conclusions:1.In the soil—Wheat--Englishgrainaphid system, the interaction of Cd and Zn promote the transfer of Cd to wheat.And the long term Cd stress can cause a certain accumulation in S.avenae.2.The interactive effect of Cd and Zn was significantly greater than that of single Cd,and the zinc showed the biggest influence; Cd 120 mg/kg and Zn 400mg/kg was the most significant level, namely these concentration showed the largest impact on the S. avenae populations.3.The long term combined stress of Cd and Zninfluenced thegrowth and developmentof S.avenaesignificantly,and high generation(10) suffered higher stress than the low generationsignificantly, the 5th was the key generation.So, the exploration about defense mechanism of S.avenae exposed to multiple heavy metal for long time has the theoretical and practical significance for the integrated manangement.