[Effects of transgenic Bt cry1Ab rice on collembolan population in paddy field]

To assess the potential ecological risk of transgenic Bt rice to non-target soil organisms in paddy field, transgenic crylAb rice KMD1 and KMD2 and their parental control rice line XS11 were planted in experimental fields, and collembolan species and their densities were investigated during grain-filling and post-harvest stages in 2003 to approximately 2004. By using an arthropod-sucking machine, two collembolan species, Entomobrya griseoolivata and Bourletiella christianseni, were collected from the leaf litter at soil surface during grain-filling stage (September,2003), and the population densities of E. griseoolivata in KMD1 and KMD2 paddy fields were significantly higher than those in XS11 paddy field. With bags contained rice stem-leaf litter and initially placed in the paddy field at harvest time (November,2003), four collembolan species, E. griseoolivata, B. christianseni, Hypogastrura matura and Isotoma monochaeta, were collected during post-harvest stages (April, 2004), and the densities of E. griseoolivata and H. matura in KMD1 and KMD2 paddy fields were also significantly higher than those in XS11 paddy field. The biomass loss of KMD1 and KMD2 stem-leaf litter was significantly greater than that of XS11's.