Expression of Bt toxin in transgenic Bt cotton and its transmission through pests {\sl Helicoverpa armigera} and {\sl Aphis gossypii} to natural enemy {\sl Propylaea japonica} in cotton plots

Abstract

The amounts of expressed Bt toxin in organs of transgenic Bt cotton NUCOTN 33B were higher (79.7--1390.0 ng/g fresh weight) than those in GK-12 (16.5--264.0 ng/g fresh weight). During the blooming period of NUCOTN 33B plants, the order of Bt toxin content was as follows: stigma, anther>ovary, petal>grouped tender tip; the Bt toxin concentrations were similar as well as equal to those in grouped tender tip, when the newly development tender leaf of 5--7 leaf stage, the young square of early squaring period and the young boll of blooming period of NUCOTN 33B plants were tested. And during the blooming period of GK-12 plants, the order of Bt toxin concentration was as follows: anther>stigma>petal>grouped tender tip>ovary; the Bt toxin concentrations were similar and equal to those in grouped tender tip, when the newly development tender leaf of 5--7 leaf stage, the young square of early squaring period and the young boll of blooming period of GK-12 plants were detected. Moreover, the detection of trace amounts of Bt toxin in young boll, anther, stigma and ovary of the control cotton line, Simian 3, might be related to pollinators. In GK-12 and UUCOTN 33B cotton plots, Bt toxin could be transmitted to cotton aphis and cotton bollworm elder larvae. In the body of P. japonica larvae and adults, trace amounts of Bt toxin were detected only in those collected from NUCOTN 33B cotton plot.