关键词: 梨小食心虫, 寄主植物, 桃, 产卵选择性

Abstract: Taking two typical soil types (limestone soil and yellow soil) in Guizhou karst areas of Southwest China as test objects, this paper measured their pH value and organic carbon content as well as the carbon isotopic composition of dominant plant species foliage and litter and of soil organic matter (SOM), aimed to approach the vertical distribution patterns of soil organic carbon (SOC) and its stable isotopic composition (δ13Csoc) in the profiles of these two soil types. Limestone soil had a higher content of SOC, as compared with yellow soil. The SOC content in the profiles of limestone soil and yellow soil varied in the range of 3.6-69.8 and 2.4-51.2 g·kg-1, respectively. The SOC in yellow soil and yellow limestone soil mainly enriched in the 0-20 cm layer, while that in the 0-60 cm profile of black limestone soil decreased gradually with depth. The δ13Csoc in the profiles of black limestone soil and yellow soil ranged from -22.9‰ to -21.5‰ and from -25.6‰ to -22.4‰, respectively.
 The δ13Csoc in yellow soil increased with increasing soil depth, whereas that  in limestone soil was generally high in surface layer, increased rapidly down to a depth of about 20 cm，  and then decreased slowly. Compared with other soils, yellow limestone soil had a wider variation range of δ13Csoc (-23.7‰ to -18.2‰) in the profile, and the δ13C (δ13Cmax-δ13Cmin) value of SOM was 5.5‰. The δ13Csoc in limestone soil profile had a wider variation range than that in yellow soil profile during the process of litter degrading into surface soil organic matter. The δ13Csoc increased by 2.6‰-3.0‰ in yellow soil profile and by 5.5‰-6.3‰ in limestone soil profile. The results suggested that the changes in δ13Csoc and SOC content with depth in different soil profiles could provide information about the input of plant residue and its degradation and accumulation in soil, and help to reveal the mechanism of soil carbon cycle and to understand the soil formation process.

Key words: Grapholitha molesta, host plant, ovipositional preference, peach.