title: Dietary Risk Assessment ofv-ATPase AdsRNAs on Monarch Butterfly Larvae.
abstract: By suppressing the expression of genes with essential biological functions,in plantaRNAi can negatively affect the development and survival of target pests. As a part of a concerted effort to assess the risks of RNAi transgenic crops on non-target organisms, we developed anin vivotoxicity assay to examine the impacts of ingested dsRNAs incurred to the monarch butterfly,Danaus plexippus(L.), an iconic eco-indicator in North America. To create the worst case scenario, the full-lengthv-ATPase AcDNAs from the target pest, western corn rootworm,Diabrotica virgifera virgifera, and the non-targetD. plexippuswere respectively cloned. A 400 bp fragment with the highest sequence similarity between the two species was used as the template to synthesize dsRNAs for the subsequent dietary RNAi toxicity assay. Specifically, newly hatched neonates were provisioned with leaf disks surface-coated withv-ATPase AdsRNAs synthesized fromD. v. virgiferaandD. plexippus, respectively, a control dsRNA, β-glucoruronidase, from plants, and H2O. The endpoint measurements included gene expressions and life history traits. The 2283 bpD. plexippus v-ATPase AcDNA contains a 99 bp 5'-untranslated region, a 330 bp 3'-untranslated region, and an 1851 bp ORF encoding 617 amino acids. The temporal RNAi study did not detect any impact toD. plexippus v-ATPase Aexpression by the assay days and treatments. This was reflected in the phenotypic impacts of dietary RNAi, in which both survival rate and development time were not affected by the uptake of ingested dsRNAs. These combined results suggest thatD. plexippuslarvae are not susceptible to dietary RNAi, therefore, the impact of transgenic RNAi plants on this non-target organism is, likely, negligible.
authors.affiliation: Key Laboratory of Bio-Pesticide Innovation and Application of Guangdong Province, Department of Entomology, South China Agricultural UniversityGuangzhou, China; Department of Entomology, University of KentuckyLexington, KY, USA.
authors.forename: Huipeng
authors.initials: H
authors.lastname: Pan
authors.affiliation: Department of Entomology, University of Kentucky Lexington, KY, USA.
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Yang
authors.affiliation: Corn Insects and Crop Genetics Research Unit and Department of Entomology, Iowa State University Ames, IA, USA.
authors.forename: Keith
authors.initials: K
authors.lastname: Bidne
authors.affiliation: Corn Insects and Crop Genetics Research Unit and Department of Entomology, Iowa State University Ames, IA, USA.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Hellmich
authors.affiliation: Department of Entomology and Nematology, University of Florida Gainesville, FL, USA.
authors.forename: Blair D
authors.initials: BD
authors.lastname: Siegfried
authors.affiliation: Department of Entomology, University of Kentucky Lexington, KY, USA.
authors.forename: Xuguo
authors.initials: X
authors.lastname: Zhou
keywords: Danaus plexippus; Diabrotica virgifera virgifera; RNAi transgenic plants; environmental risk assessment; life history traits; non-target organisms