Submitted to: PLoS One
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/17/2013
Publication Date: 11/11/2013
Citation: Sun, X., Liu, H., Zhang, A., Ai, C., Zhou, S., Zhou, C., Wang, M. 2013. Transgenic bt rice does not challenge host preference of the target pest of rice leaffolder, Cnaphalocrocis medinalis (Lepidoptera pyralidae). PLoS One. 8(11):e79032. Interpretive Summary: Transgenic crops that resist insects have been introduced worldwide and numerous transgenic rice cultivars have been successfully developed. Laboratory and field investigations have confirmed that transgenic rice can effectively control infestation of target moths. However, it is still not clear if the volatile chemical compounds emitted from transgenic rice are different from non-transgenic rice, and whether they influence searching behaviors of moths for their host and/or egg laying site. We evaluated this in the current study and found no significant differences in volatile chemical emissions, physical characteristics of rice leaves, electronic nose radar map of plantations, or in numbers of female moths laying eggs between transgenic and non- transgenic rice. The results from this research will be used to help scientists and growers better understand the interaction mechanisms between transgenic rice and associated insect pests, as well as assist in the assessment of ecological impacts of transgenic rice plantations where planted in large scale.
Technical Abstract: Transgenic Bt rice line T2A-1 expressed a synthetic cry2A gene and exhibited high resistance to Lepidoptera pests, including Cnaphalocrocis medinalis (Guenée) (Lepidoptera: Pyralidae). Plant volatile cues usually are essential for phytophagous insects to locate the food source and oviposition site. The question arose, if the volatile compounds can be altered in Bt rice, which may further influence the behavior of C. medinalis searching for oviposition sites or foraging natural enemies. In this research, results of electronic nose analysis showed that radar map of Bt rice cultivars was analogous to the non- Bt rice cultivars in each growing stage. Although PCA analysis was able to partly discriminate for some sensors between Bt vs. non-Bt rice cultures, it could not separate Bt species from non-Bt species. The headspace volatile profiles collected from Bt and non- Bt rice cultivars in the stage of seedling, booting or tillering were similar. In addition, there was no significantly quantitative difference for each compound identified by GC-MS between Bt and non- Bt rice cultivars in same stage. Moreover, the densities of the tubercle papicles and trichomes on adaxial surfaces were statistically equal in Bt and non-Bt rice. Finally, the target pests, C. medinalis, were attracted to host rice plants, but could not distinguish the transgenic and the isogenic rice lines. Based on above results, we conclude that Bt rice line T2A-1 did not affect the volatile profiles and physical characteristics of rice and has no negative impact on the target insect, C. medinalis, in food searching and oviposition behaviors. Our results add to the mounting evidence that Bt rice has no negative impact on the target insect behavior.