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Transgenic Bt-cotton (Gossypium hirsutum L.) GK 12 is commonly used for control of lepidopteran pests in China, but concerns exist regarding possible unintended effects on soil microbial communities. Bacterial population sizes and community structures in the rhizosphere soil under intensive cultivation of GK 12, its near-isogenic parent Simian 3 and a conventional cotton DP 5415 were analyzed during 2009 to 2011 by quantitative polymerase chain reaction (qPCR) and denaturing gradient gel electrophoresis (DGGE). Dehydrogenase, urease, and phosphatase activities were also measured. It was found that these microbial-related parameters were significantly influenced by variations due to the year and plant growth stage. There were occasional differences in bacterial population size and community structures at some growth stages, but they were not manifested throughout the growing cycle and were not considered meaningful. Generally no significant differences were found in selected enzymatic activities, and bacterial population sizes and community structures in the rhizosphere soil of GK 12 and Simian 3. Three different species or bands were unique to GK 12 and Simian 3, but they were unamplifiable. The resolvable band profile or annotatable species composition was not different between GK 12 and Simian 3. Therefore, the data of this study did not show any significant and permanent impacts of Bt-insertion in GK 12 on selected enzymatic activities, bacterial population size, and community structures in the rhizosphere soil during 3-yr tests in northern China. [ABSTRACT FROM AUTHOR]

The alpha-proteobacteria of the genus Wolbachia is a widespread group of maternally inherited endosymbionts of arthropod and nematode hosts. Wolbachia infection induces a range of host phenotypes, including cytoplasmic incompatibility, male killing, feminization, and induction of thelytokous parthenogenesis. Heterogony (cyclical parthenogenesis) is a remarkable characteristic of oak gallwasps, Cynipini, the largest tribe of the Cynipidae. A few species of Cynipini are exceptional in that they are univoltine and exhibit thelytokous parthenogenesis, probably because they lost the arrhenotokous generation of their heterogonic ancestor species due to Wolbachia infection. In this study, the presence of Wolbachia was detected using polymerase chain reaction primers for the wsp genes in a thelytokous parthenogenetic species [ Dryocosmus kuriphilus (Yasumatsu)] (Hymenoptera: Cynipidae: Cynipini). Approximately 29.8 and 87.1% of adults of the Zhuzhou and Fuzhou strains, respectively, were infected with Wolbachia while all females of the remaining four strains collected from other localities in China were Wolbachia free. The length of the wsp fragment of Zhuzhou and Fuzhou strains was found to be 573 and 561 bp, respectively. The nucleotide sequence of the bacterial wsp fragment indicated that the endosymbiotic bacteria of the Zhuzhou and Fuzhou strains are members of supergroup A, but belong to different clades; they probably originated from two independent infection events. In conclusion, thelytokous parthenogenesis of D. kuriphilus is not caused by Wolbachia infection and the deletion of the arrhenotokous generation is thus not associated with such an infection. [ABSTRACT FROM AUTHOR]