title: Bacillus thuringiensis insecticidal crystal proteins affect lifespan and reproductive performance of Helicoverpa armigera and Spodoptera exigua adults.
abstract: Being delivered as sprays or expressed in plant, Bacillus thuringiensis (Bt) crystalline proteins (Cry toxins) display insecticidal activities against numerous Lepidopteran, Dipteran, and Coleopteran larvae. Comparative study of toxicities of Bt Cry toxins between larvae and adults may afford important new insights into the interactions of the toxins with receptor proteins in host insect, and represent intriguing targets for the control of insect pests. However, the effectiveness of Bt Cry toxins in insect adults has paid less attention. In the present article, the effectiveness of Cry1Ac and Cry1Ca on lifespans and reproductive performance of Helicoverpa armigera (Hübner) and Spodoptera exigua (Hübner) adults were evaluated by in vivo experiments. Considering transgenic plants express modified, truncated versions of cry genes yielding active toxin fragment, we used activated Bt toxins at the concentration of 500, 100, and 20 microg/ml in a 10% sucrose aquous solution. At the highest concentration, Cry1Ac and Cry1Ca shortened 48.1 and 48.9% of H. armigera female lifespan, and 43.5 and 38.5% of S. exigua female lifespan, and they reduced 37.8 and 40.3%, and 50.5 and 47.4% of H. armigera and S. exigua male lifespans respectively. Bt toxins negatively affected copulation. Exposure to 500 microg/ml of Cry1Ac and Cry1Ca greatly reduced 50.0 and 46.8%, and 58.7 and 57.3% spermatophore acceptance by H. armigera and S. exigua females, respectively. Similarly, Cry1Ac and Cry1Ca exposure decreased 40.0 and 50.3%, and 61.3 and 60.0% of spermatophore transfer by H. armigera and S. exigua males, respectively. Moreover, exposure females rather than males to 500 microg/ml of Cry1Ac and Cry1Ca significantly dropped 57.5 and 57.5% of the number of eggs laid by H. armigera, and 35.4 and 45.8% of the number of egg masses deposited by S. exigua. In contrast, both Cry1Ac and Cry1Ca did not negatively influence the egg hatchability. At the middle and the lowest concentrations, however, the biological effects of Cry1Ac and Cry1Ca on lifespans and reproductive performance partially or completely disappeared.
authors.affiliation: Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yan
authors.initials: Y
authors.lastname: Ma
authors.forename: Pin-Jun
authors.initials: PJ
authors.lastname: Wan
authors.forename: Li-Li
authors.initials: LL
authors.lastname: Mu
authors.forename: Guo-Qing
authors.initials: GQ
authors.lastname: Li
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000235:genetics*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics / Q000494:pharmacology*; D002681:China; D004305:Dose-Response Relationship, Drug; D004731:Endotoxins / Q000235:genetics / Q000494:pharmacology*; D005260:Female; D006460:Hemolysin Proteins / Q000235:genetics / Q000494:pharmacology*; D008136:Longevity / Q000187:drug effects; D008297:Male; D009036:Moths / Q000187:drug effects* / Q000502:physiology; D012098:Reproduction / Q000187:drug effects; D013045:Species Specificity
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis