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Ecological Risk Assessment of Bt Rice on Arthropod Community and Dominant Natural Enemies in Rice Paddy Habitat

Author: LiuZhiCheng
Tutor: HuZuo
School: Zhejiang University
Course: Agricultural Entomology and Pest Control
Keywords: Bt rice cry1Ab gene cry1Ac gene ecological risk assessment arthropod herbivores Sogatella furcifera Nephotettix cincticeps Nilaparvata lugens Cnaphalocrocis medinalis parasitoid wasp Insect predator Cyrtorrhinus lividipnnis spider Tetragnatha maxillosa Ummeliata insecticeps Pirata subpiraticus community structure functional responses population density growth and development reproduction
CLC: S185
Type: PhD thesis
Year: 2002
Downloads: 381
Quote: 10
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Abstract

Facing to the fact that biosafety of transgenic insect-resistant plant is having become a focus in the world, a series of laboratory and field studies using four transgenic Bt rice homogenous lines, i.e. TT9-3 and TT9-4 with a hybrid gene of cry] Ab / cry 1 Ac, which are indica rice with their parental control cultivar 1R72, as well as KMD1 and KMD2 with crylAb gene, which arejaponica rice with their parental control cultivar Xiushui 11, were carried out to evaluate the ecological risk of transgenic rice released in the environment. The result are as follows:1 Impact of Bt Rice on Arthropod Community Structure in Rice Paddy HabitatThe dominant group compositions of arthropod guilds were almost the same between Bt rice paddy habitats and their control. Both for Bt rice and the control, planthoppers and leafhoppers, braconids and pteromalids, and sminthurids and tomocerids were the dominators among non-target herbivores of Bt rice, parasitoids and detritivores, respectively. As to the predators, the dominators were the insect predators including capsid bugs, and longlegged flies or empidids, and spiders including tetragnathids, linyphiid and wolf spiders. The abundance of parasitoids in Bt rice was apparently lower than the control, while no significant difference (.P>0.05) was found. As to arthropod community structure parameters such as species richness, Shannon-Winner diversity index, evenness index, dominant index and their dynamics in rice paddy habitat, there were no marked difference between Bt rice and the control. The arthropod community structure in Bt rice paddy habitat was very similar to the control.Fn general, Bt rice was no markedly negative effect on arthropod community structure in rice paddy habitat.2 Impact of Bt rice on Sub-community Structure and the Dominator Population Dynamics of Bt rice Non-target Herbivores in Rice Paddy HabitatThe species composition of non-target herbivores sub-community in Bt rice paddy habitat was similar to the control, in which planthoppers and leafhoppers were the dominant groups. The differences in the whole individual number of non-target herbivores, the dominance distribution of each group, total individual number and population density dynamics of dominant groups such as planthoppers and leafhoppers, and the population density dynamics of Sogalella furcifera, Laodelphax striatellus and Nephotettix cincticeps varied with the lines of Bt rice, the tested year and the tested place between in Btrice fields and the control. In general, the differences were not significant, while very clear in some cases. In theses cases, the individual number and population density for Bt rice were significantly higher or lower. According to theses results, it was clear that Bt rice sometime could perform negative or positive effects on the whole individual number and population density of non-target herbivores, particularly for the dominant groups or species.3 Impact of Bt rice on Sub-community Structure and the Dominator Population Dynamics of Parasitoid Wasps in Rice Paddy HabitatIn contrast to the control, the family composition of parasitoid wasps and their dominance distribution were not significant different in Bt rice fields. While the differences in the individual number and population density between Bt rice and the control varied with parasitoid groups. In general, the individual number and population density of parasitoid wasps using target insect pests of Bt rice as hosts, including braconids and ichneumons, were less or lower in Bt rice fields than the control, and even the differences between Bt rice and the control reached the stastically significant levels. In contrast, the difference between Bt rice and the control did not encounter to the parasitoid wasps using non-target insect pests of Bt rice.4 Impact of Bt rice on Sub-community Structure and the Dominator Population Dynamics of Insect Predators in Rice Paddy HabitatFor total individual number and total density dynamics of insect predators, total individual numbe

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