title: Use of a dietary exposure system for screening of insecticidal compounds for their toxicity to the planthopper Laodelphax striatellus.
abstract: We developed a dietary exposure assay for screening insecticidal compounds for their toxicity and for assessing the side effects of insecticidal proteins produced by genetically engineered (GE) plants on the planthopper Laodelphax striatellus Fallén. The fitness bioassay confirmed that the diet fulfills the requirements to be used in the dietary exposure system. To validate the efficacy of the dietary exposure system, nymphs of L. striatellus were fed diets treated with different concentrations of an inorganic stomach poison, potassium arsenate (PA), or a cysteine protease inhibitor, E-64. The results showed that with increasing concentrations of E-64, the larval development time was prolonged, the adult weight was reduced and the survival rate of L. striatellus was decreased. Similarly the survival rates of L. striatellus consistently decreased with increasing PA content in the diet. The data indicate that the dietary exposure assay is able to detect the effects of insecticidal compounds on L. striatellus. Subsequently, this assay was successfully used for assessing the potential toxicity of Cry2Aa. The results showed that L. striatellus larvae were not negatively affected when fed the artificial diet containing purified Cry2Aa at 300 μg/g diet. In the assay, the stability and bioactivity of crystal (Cry) proteins in the food sources were confirmed by enzyme-linked immunosorbent assay and sensitive-insect bioassays. These results show that L. striatellus is not sensitive to Cry2Aa. We conclude that the dietary exposure system is valid and useful for assessing the toxicity of insecticidal compounds produced by GE plants on planthoppers.
authors.affiliation: State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing; Nanjing Agricultural University, Nanjing, China.
authors.forename: Zeng-Xia
authors.initials: ZX
authors.lastname: Wang
authors.forename: Ke-Jian
authors.initials: KJ
authors.lastname: Lin
authors.forename: Jörg
authors.initials: J
authors.lastname: Romeis
authors.forename: Yong-Lei
authors.initials: YL
authors.lastname: Liu
authors.forename: Ze-Wen
authors.initials: ZW
authors.lastname: Liu
authors.forename: Yun-He
authors.initials: YH
authors.lastname: Li
authors.forename: Yu-Fa
authors.initials: YF
authors.lastname: Peng
mesh_terms: D000818:Animals; D001149:Arsenates / Q000494:pharmacology; D001413:Bacillus thuringiensis / Q000737:chemistry; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004731:Endotoxins / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006430:Hemiptera / Q000187:drug effects* / Q000254:growth & development; D007306:Insecticides / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects; D007930:Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D008297:Male; D009758:Nymph / Q000187:drug effects; D012275:Oryza / Q000382:microbiology; D030821:Plants, Genetically Modified / Q000737:chemistry / Q000235:genetics; D017680:Potassium Compounds / Q000494:pharmacology; D018675:Toxicity Tests / Q000379:methods*
chemical_list: D001149:Arsenates; D015853:Cysteine Proteinase Inhibitors; D004731:Endotoxins; D007306:Insecticides; D017680:Potassium Compounds; D007930:Leucine; C024974:E 64
keywords: Cry2Aa; E-64; genetically engineered rice; potassium arsenate; risk assessment