Effects of transgenic Bt corn pollen on a non-target lycaenid butterfly, Pseudozizeeria maha
2005
Shirai, Y. (National Inst. for Agro-Environmental Sciences, Tsukuba, Ibaraki (Japan)) | Takahashi, M.
To evaluate the effect of pollen released from transgenic insecticidal corn on non-target lepidopteran insects, corn pollen deposition density on the leaves of sunflower and black nightshade was measured near a cornfield. At 12 d from the start of anthesis, the highest cumulative pollen density on leaves was approximately 160 grains per square cm at 1 m from the edge of the cornfield, falling to 20 grains at 5 m and less than 10 grains at 10m. The pollen density calculated using a mathematical model in a previous study evidently had overestimated values. To evaluate precisely the effect of corn pollen expressing Bacillus thuringiensis (Bt) endotoxin (Cry lAb) on the survival of lepidopteran larvae, we im-proved the bioassay methods using the pale grass blue. Pseudozizeeria maha. the leaf disc of the wood sorrel. Oxalis corniculata. and transgenic Bt corn (Event-176). When the surface of the leaf was pretreaed with a small amount of 80% acetone solution, the preselected pollen dose was successfully applied onto the leaf disc. Larval survival of P. maha was significantly affected at pollen density of more than 20 grains per square cm on the leaf disc. It is unlikely that pollens from Bt corn expressing Cry lAb have wide-scaled deleterious effects on non-target P. maha near cornfields. because of low pollen deposition dose on the leaves.
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