Study On The Ecology Of Aphid Under Stressed Condition

Aphids are small sap-sucking insects whose characters include cyclic parthenogenesis(parthenogenesis generation and sexual reproduction genetation are alternative),multiple life cycles and ovoviviparous.Aphids which are parthenogenesis have a great reproductive capacity and growth rate.These features allows them to increase population size rapidly.Most of the agricultural crops serve as host plants for aphid species whose feeding reduces harvest yields.Air pollution,abuse of pesticides and many kinds of factors such as extreme high temperature,microwave and radiation etc have a great selection pressure to the aphids' growth,reproduction and survives.It makes the aphids develop a complicated way of life and adaptive mechanism during long evolution process.Therefore,study the influence of bad environment on Aphids has an important meaning for understanding their system evolution and adaptive mechanism.1.Clone and sequence analysis of cDNA fragment of heat shock protein 70 gene in cotton aphidThe cotton aphids' body color shows polymorphism adapting to temperature change, supposing it relates with HSP.The study is to amplify the partial cDNA sequences of HSP 70 gene of Aphis gossypii Glover and study the features of the sequences, possible relationship between HSP 70 gene and the body color.According to the conserved regions of other known insects,designed a pair of specific primers and used the RT-PCR method to amplify the partial sequences of HSP 70 from cotton aphid treated with high and low temperature.A fragment of cDNA which is 783 bp in size was amplified(Genbank accession No. EU109426).Nucleotide sequence analysis demonstrated that the nucleotide sequence of the yellow type and green type are same. HSP70 is not the reason to cause variation of body color in cotton aphid.Meanwhile,The deduced amino acid sequence contains 261 residues. Analyzed results show that there is high homology of amino acid sequence between the cotton aphid and other insects. The abtained 783 bp nucleotide sequence encoded the partial amino acid sequence of cotton aphids' HSP 70 gene.2.Influence of different time uv treated english grain aphid to the biological parameters of their offspringBy uv treatment of different time to two types of english grain aphid on different variety,analyze the biological parameters of their offsprings.The results show that different variety and time of uv treatment have an effect on the offspring'growth and development.There is an interaction between them.(1)On high resistent variety Astron(German variety),short time uv treatment(1h,2h,3h)to two types of english grain aphid does not influence the growth and development of their offspring.But there are obvious differences with the long time uv treatmen(t4h,6h,8h).(2)On resistent variety xiaoyan-22(Chinese variety),short time uv treatment(1h,2h,3h)to the red type has an inhibitory effect to the growth and development of its offspring.But the long time uv treatmen(t4h,6h,8h)has no effect.Uv treatment of different time to the green type has an inhibitory effect to the growth and development of its offspring.(3)On variety xiaoyan-22, uv treatment of 1h and 2h to the red type has a great inhibitory effect to the growth and development of its offspring than the green type's.(4)The ecological impacts of the uv radiation to aphid has inherited to filial generation.Both of the variety Astron and xiaoyan-22,uv treatment of different time to two types of english grain aphid has an inconsistent effect to the growth and development of their offspring.There are differences between them.The results of this study will benefit the further research of stress-resist ability mediated by HSP70 and function way, mechanism of HSP70 for Implementing its functions.Meanwhile,it also helps to study the influence of ultraviolet radiation to biotic genetic material and protein metabolism.It can provide theoretical basis for evolution of aphid.