Toxicological assessment of pollen from different bt rice lines on Bombyx mori (Lepidoptera: Bombyxidae).
The relative toxicity of Bt rice pollen to domestic silkworm, Bombyx mori Linnaeus (Lepidoptera: Bombycidae), was assessed by a leaf-dip bioassay under laboratory conditions. Silkworm first instars were sensitive to pollen from Bt rice lines, B1 and KMD1, but were not sensitive to pollen from Bt rice line TT9-3. First instars were 1.34-2.12 times more sensitive to B1 pollen than older instars. Bioassays of subacute toxicity under a worst-case scenario suggested that continuous exposure to a sublethal dose of B1 pollen or equivalent doses of non-Bt rice pollen affected silkworm survival and development. Young larvae were more affected by continuous exposure to Bt pollen than older larvae but less affected by non-Bt pollen. Ultrastructural observations showed that Cry proteins associated with Bt pollen were released into the larval lumen and resulted in pathological midgut changes and negative impacts on silkworm survival and development. However, considering that the sublethal dose of Bt pollen (LC15) used in this study is equivalent to the highest detected density of rice pollen on mulberry leaf under field conditions and that the likelihood of such high density of rice pollen occurring in the fields is extremely low, we suggest that the risk of Bt rice pollen on silkworm rearing is negligible.
Yao
Hong-Wei
HW
State Key Laboratory of Rice Biology, Institute of Insect Sciences, Zhejiang University, Hangzhou 310029, China.
Jiang
Cai-Ying
CY
Ye
Gong-Yin
GY
Hu
Cui
C
Peng
Yu-Fa
YF
D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism / Q000633:toxicity*; D001835:Body Weight / Q000187:drug effects; D012831:Bombyx / Q000187:drug effects* / Q000254:growth & development / Q000648:ultrastructure; D004731:Endotoxins / Q000235:genetics / Q000378:metabolism / Q000633:toxicity*; D041981:Gastrointestinal Tract / Q000187:drug effects / Q000648:ultrastructure; D006460:Hemolysin Proteins / Q000235:genetics / Q000378:metabolism / Q000633:toxicity*; D007306:Insecticides / Q000378:metabolism / Q000633:toxicity; D007814:Larva / Q000187:drug effects / Q000648:ultrastructure; D008854:Microscopy, Electron; D012275:Oryza / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000378:metabolism; D011058:Pollen / Q000378:metabolism*; D011679:Pupa / Q000187:drug effects; D023382:Toxicity Tests, Acute
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; D007306:Insecticides; C030956:insecticidal crystal protein, Bacillus Thuringiensis