| Using transgenic Bt cotton"GK22"and conventional cotton"SM3", transgenic Bt+CPTI genes cotton"SGK321"and conventional cotton cotton"SY321", a series of researches were conducted in laboratory and field, We constructed life table of laboratory population and natural population of Podoptera litura on four different cotton varieties, studied the behavior habits and analyzed the influences on the growth,development and nutritional indices of the P. litura on the different cotton varieties, and detected effects of the four different cotton varieties on three detoxification enzyme. The results were as following:By studying different cotton varieties selectivity of larvae feeding and adult oviposition of P. litura, we found that transgenic cotton had no negative trend for larvae feeding, but also had positive trend. The tender head of transgenic Bt+CPTI genes cotton had more attractive to 2nd and 3rd instar larvae feeding than conventional cotton, the number of P. litura on transgenic Bt+CPTI genes cotton were 10.7 and 9, when there were 7 and 5.7 on conventional cotton. We also found transgenic cotton had no negative trend for adult oviposition.By constructing life tables of laboratory population of P. litura in four cotton varieties, we found that the index of population trend(I) of continuous generation fed on these four cotton varieties (conventional cotton"SM3",transgenic Bt cotton"GK22",conventional cotton cotton"SY321"and transgenic Bt+CPTI genes cotton"SGK321") were 835.50,552.09,947.66,588.83 and 767.62,816.64,788.48,641.88, all larger than 1, the laboratory population were uptrend. the index of population trend(I) of the 2nd generation on transgenic Bt cotton"GK22"and transgenic Bt+CPTI genes cotton"SGK321"were 816.64 and 641.88, higher than the 1st generation, which were 552.09 and 588.83. but conventional cotton were on the contrary. It is showed that transgenic cotton not only had no resistance, but also beneficial to population increase of P. litura.By constructing life tables of natural population of P. litura in four cotton varieties, we found that the index of population trend(I) of the transgenic Bt cotton"GK22",transgenic Bt+CPTI genes cotton"SGK321"were 1.74,1.85,slightly lower than conventional cotton"SM3"and"SY321", which were 1.84 and 2.74, but all larger than 1, the natural population were uptrend, it is showed that transgenic cotton had control function to P. litura, but no significant, and did not control the natural population. By analyzing the important factors of population control further, we found that the key stage of the P. litura was 1st to 2nd instar larvae, the survival rate of this state(Si) only were 0.0191-0.0262. The major control factors of population control on different types of cotton fields were loss and wash away, the exclusion index of population control(EIPC) were 9.6428-19.5248. The second control factors of population control were predated, and the EIPC were 5.1836-10.3196. The third control factors were virosis and natural death, the EIPC were 1.3172-1.6909 and 1.3637. And found that the EIPC of predated on transgenic cotton"GK22"and"SGK321"were 9.6232 and 10.3196, all higher than conventional cotton"SM3"and"SY321", which were 6.6992 and 5.1836.By studying the influences of the different cotton varieties on the growth and development of larvae of P. litura. we found that effects of different cotton varieties on developmental duration of larvae of the first generation and the second generation was no significant. But had significant differences in the survival rate of the larvae and pupa weight of the two generations, the survival rate of the larvae of the fist generation when feeding on transgenic Bt cotton"GK22"and transgenic Bt+CPTI genes cotton"SGK321"were 68.7% and 71.7%, lower than conventional cotton"SM3"and"SY321", which were 83.8% and 82.9%, and the pupa weight of the fist generation when feeding on transgenic cotton were 328.8±28.6mg and 332.2±22.0mg, aslo lower than conventional cotton, which were 344.1±21.6mg and 347.0±22.7mg. But in the second generation, the survival rate of the larvae feeding on transgenic cotton went up, which were 81.9% and 92.0%, higher than the conventional cotton,which were 66.7% and 80.8%, and the pupa weight were 337.3±15.5mg and 393.1±9.4mg, more significantly higher than the conventional cotton, which were 312.2±15.7mg and 334.5±12.8mg. It is concluded that there was no significant influences on the growth,development and nutritional indices of the larvae of P. litura when feeding on the transgenic cotton, and even going for P. litura.By analyzing the influences of the different cotton varieties on the nutritional indices of the third, forth and sixth instar larvae of P. litura, we found that the relative growth rates of the forth instar larvae feeding on transgenic Bt cotton"GK22"was 0.86, significant higher than conventional cotton"SM3", which was 0.76, but on transgenic Bt+CPTI genes cotton"SGK321"was 0.75, more significantly lower than conventional cotton"SY321", which was 0.83. On top of that, relative feeding rate,digested food efficiency,ingested food efficiency,approximate digested rate,relative metabolize rates and relative growth rates of the three instar larvaes when feeding on transgenic cotton had no significant differences compared to the conventional cotton. It showed that it had no qualitative influences on nutritional indices of the larvae of P. litura when feeding on the transgenic cotton.By detecting effects of different cotton varieties on three detoxification enzymeα-naphthylacetate esterase, glutathione-S-transferase (GST) and mixed function oxidase (MFO) of P. litura, we found that after feeding with four cotton varieties, the activities of three detoxification enzyme in P. litura had no significant differences among transgenic cotton and conventional cotton. It showed that influences on three detoxification enzyme of the larvae of P. litura when feeding on transgenic cotton and conventional cotton was no significant. All in all, this experiment demonstrated that the transgenic cotton didn't have resistance on P. litura. |
PDF Full Text Request