The Toxicity And Toxicity Mechanism Of Transgenic Betula Platyphylla With Bt+spider Peptide Gene

In this paper, we determined the toxicity of transgenic Betula platyphylla with Bt+spider peptide gene. Larvae of Lymantria dispar were feed on leaves of transgenic Betula platyphylla with Bt+spider peptide gene, The mortality, reduced ratio of weight, ecdysis index and schedule time of every instar. The results showed that the foreign genes had integrated into the genome of Betula platyphylla, and expressed.The transgenic Betula platyphylla could significantly extend scheduled time of every instar. 4.38~5.73d was extended for 1st instar, 0.32~0.91d for 2nd instar and 0.62-1.08d for 3rd instar. Most of controlled larvae could develop into 5 1 instar and complete the development of larva, while none for treated larvae. The transgenic Betula platyphylla could restrain the increase of the weight of larva, and this function was more and more significant with the increase of the time of feeding. There was no significant difference between the weight of controlled and treated 10-d old larvae. However, by 20d, the weight of controlled larvae was 2.41-3.95 times of that of treated larvae, and about 5 times by 30d, 6.75-7.43 times by 40d. The transgenic Betula platyphylla could kill larva. The total mortality of treated larvae was 95.89%, which was 4. Itimes of that of controlled larvae. The mortal peaks of larvae wasl-7d and 29-35 d, in which most of treated larvae was killed. The transgenic Betula platyphylla could reduce the ecdysis index of larvae. The ecdysis index of controlled larvae was 3.323 by 30d, while 2.933-3.038 for the treated. The transgenic Betula platyphylla could reduce the feeding of larvae. With the increase of the time of feeding, the difference of food taken between the controlled and treated became larger. The food of controlled larvae taken was 0.105293-0.13750 grams than that of the treated by 3 d. and 0.529094-0.64103 grams by 21d.The toxicity of individuals of the transgenic Betula platyphylla was different.Foreign gene could destroy larva's mid-intestine, and reduce its appetite. Observation by microscope showed that the gaps between mid-intestine cells was extended in treated larvae, and the nucleus were destroyed, the gap between peritrophic membrane and mid-intestine cells was appeared, parts of peritrophic membrane was broken off from mid-intestine cells.