No abstract

No abstract

No abstract

The insecticidal activity of transgenic cottons expressing endotoxin protein of Bacillus thuringiensis Berliner (Bt cotton) was quantified by measuring survival of tobacco budworm, Heliothis virescens (F.), larvae caged on different plant structures for varying lengths of exposure. Percentages of larvae surviving were measured on Bt cottons expressing Cry1Ab and CrylAc protein. Plant structure (terminal, leaf, square or boll) did not affect larval survival, and survival did not differ significantly between CrylAb and CrylAc cottons. Larvae exposed to Bt cotton for only 24 h had higher initial survival than larvae exposed for 48, 72 and 96 h. Larvae first exposed to Bt cotton at 4 d of age had higher survival than those first exposed as neonate or 2-d-old larvae. Survivorship of neonate and 4-d-old larvae exposed to CrylAc cotton was significantly reduced with only 48 h of exposure to the insecticidal plants. Seven-day-old larvae exhibited no significant reduction in survivorship with exposure to CrylAc cotton for 48 h.

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.