Effects Of Elevated CO₂ On Aphis Gosspii On Gossypium Hisutum And Its Symabionts

With elevating of CO2 concentration in the atmosphere, plant morphology, structure, chemical component contents, physiology metabolism have been changed obviously. For example N concentration and secondary metabolites of plant have been increased; however the C: N of pants has been decreased. Plant biomass has been increased. That indirectly impacted herbivore insects.In this study, we used C3 cotton(Gossypium hirsutum) and cotton aphid(Aphis gossypii) to analyze the effects of elevated CO2 750 ppm on plants, aphids and the symbionts. In this study, the extraction of cotton phloem sap was measured by the method of EDTA. We used LCMS measured the relative concentrations of amino acids and sugars, and RT-PCR to investigate the relative concentrations of Buchnera.The result as follows:1) Elevated CO2 not only raised cotton height, but also changed the concentration of some amino acids in cotton phloem sap, especially histidine. However, cotton phloem sap essential amino acids concentrations had been increased after aphid feeding cotton phloem sap histidine concentration rose. Elevated CO2 increased the concentration of leaf free amino acids and total phenols. After aphid feeding plant total phenols concentration rose.2) Under high CO2 concentration, aphid weight had been decreased, and cotton population had been increased. Elevated CO2 decreased concentration of aphid essential amino acids lysine, histidine and tryptophan. There were no consistency of aphid amino acids and cotton phloem sap amino acids.3) Under high CO2 concentration, there was no change of aphid symbionts species. However, the concentration of aphid Buchnera decreased more than half of the aphids lived under ambient CO2 387 ppm.After aphids feeding cotton phloem sap, the concentration of amino acids had been changed, which indicated that aphids can stimulate the movement of amino acids. Under ambient CO2, Buchnera colonying aphids has positive effect on the aphid that feed low nitrogen plant. Symbiont can assist aphids adapted new environment. The research indicates that elevated CO2 affected cotton leaf total phenol and phloem nutrient chemistry, cotton aphid will not break up.