Nucotn 33B (R) and Delta and Pineland cottons: Pink bollworm (Lepidoptera : Gelechiidae) infestations and Cry1Ac toxic protein in overwintered and seeded cottons with bioassay mortalities of other lepidopterous larvae.

摘要

NuCOTN 33B(R) (Bt) and Delta and Pineland (DPL 5415) cottons were grown in furrow and furrow plus drip irrigated cotton plots in Arizona. CrylAc toxic protein produced in Bt cotton was measured with commercially available enzyme-linked immunosorbent assay (ELISA) kits. Irrigation type had no effect on CrylAc measured in cotton leaves or bolls. First-instar, laboratory-reared pink bollworm (PBW), Pectinophora gossypiella (Saunders), larvae placed on Bt cotton bolls collected in field throughout the season died (100%) irrespective of decreasing CrylAc toxic protein levels in late season bolls. PBW field infestations averaged over 2.5 live larvae per (DPL 5415) immature green boll compared with no live larvae in Bt immature green bolls. Results were similar for PBW infestations of open mature bolls on Bt and DPL 5415 whole cotton plant samples. Two unexplained PBW larval exit holes occurred in open mature Bt bolls. These could have been on plants from non-Bt contaminated seed in Bt seed lots. In bioassays, using laboratory-reared cabbage looper (CL), Trichoplusia ni (Hubner), larval mortality percentages decreased with decreasing CrylAc content measured in Bt leaves. CrylAc protein was expressed in cotton bolls and leaves from overwintered Bt plants. PBW and tobacco budworm (TBW), Heliothis virescens (L.), larval mortalities averaged 99 and 100% (overwintered and 2002 seeded Bt cotton), respectively, compared with averages of 40 and 3%, respectively, on DPL 5415 bolls and leaves (overwintered and 2002 seeded cotton).