The Effects Of Three Transgenic Maize On Population Dynamics And Growth Of Natural Enemies Of Pests

Genetically modified crops must besubjectedto the intermediate testtosystematical lyassesstheir ecological risks in different ecosystems before commercialization..The study on whether the protein expressed in transgenic insect resistant maizes has an impact on the non-target pests or natural enemies in the food chains has just started in China.Through a two-year field survey,the effects of three transgenic maize events(Crylle,CrylAb/Cry2Aj and GlOevo-epsps,CrylAb and EPSPs)on the target pest,non-target pestand natural enemies in the field were studied with zong-31,Ruifeng-1 and DBN318 as the corresponding controls.The effects of the three transgenic maizes on the controling effecacy,on the growth and reproduction of Mythimna separata(Walker)(Lepidoptera:Noctuidae)and natural enemy predator Arma chinensis(Fallou)were also studied in the laboratory.The results will provide reference for the further evaluation of ecological safety of Bt crops and for the biological control in transgenic plant fields.The main results are as follows:The field system survey showed that transgenic maize IE09S034 had significant influence on the growth of Ostrinia furnacalis population and had no influence on the number and dynamics of the population of either non-target insect pests,such as planthoppers,trips,leaf armour,or natural enemies like ladybug,small flower bugs and grass flies.Transgenic double resistance 12-5 maize had significant effects on target pests corn borer and other insect pests.There were almost no symptoms of Asian corn borer,and there was no significant effect on the number and dynamics of the population of the non-target insect pests,such as the planthoppers,thrips,leaf annour,the natural enemy ladybug,the small flower bugs and the grass flies.Transgenic C0030.3.5 maize successfully controlled O.furnacalis population,and it had no effect on the number of dynamic and non-target pests and their enemies.The indoor experiment showed when each instar armyworm larvae were fed with IE09S034,the elder the larvae,the higher the survival was.There was no significant difference of the normal pupae between the transgenic maizes event and the control.The transgenic event had a significant killing effect on the 1st instar larvae,and the survival rate was 46.2%,but the acute killing efficiency was poor.Once the larvae were older than 3-instar,the effects of transgenic event on body weight,body length,developmental duration were not significant.Laboratory experiment showed that transgenic 12-5 maize had ideal resistance to 1-5 instar larvae.The mortality of 1-3 instar larvae was nearly 100%,and the acute killing efficiency was strong.After the 3rd instar larvae were treated by the transgenic event for 3 d,the body weight and body length of the armyworm were both significantly decreased,just up to 65.6%and 79.8%of the corresponding control respectively.Cry1Ab/Cry2Aj protein significantly inhibited the body weight and body length,and the longer the feeding time,the more remarkable the effect became.The developmental duration of the 3rd instar and 4th instar larvae was significantly prolonged for 4.5 d and 3 d respectively.The pupal weight of the 4-6 instar larvae fed with transgenic materials was significantly different from that of the control.The fecundity of adults which were fed with transgenic plants in the 5th and 6th instar was significantly different from that of the control.The egg number of the control group was 4.5 times that of the transgenicgroup.Laboratory experiment also showed that the transgenic C0030.3.5 maize had ideal resistance to 1-5 instar larvae.The mortality of 1-4 instar larvae was nearly 50%,and the acute killing efficiency was strong.After the 3rd instar larvae were treated by the transgenic event for 3 d,the body weight and body length of the armyworm were just 62.8%and 80.4%of the corresponding controls,respectively.Cryl Ab protein inhibited the body weight and body length,and the longer the feeding time,the more remarkable the effect became.The developmental duration of the 4th instar larvae was significantly prolonged for 2.2 d.The pupal weight of the 4-6 instar larvae fed with transgenic materials was significantly different from that of the control and the pupal weight wasup to 53.9%?56.8%and 54.6%of control.The fecundity of adults which were fed with transgenic plants in the 5th and 6th instar was significantly different from that of the control.The eggs number of the control group were 5.1 times and 4.7 times that of the transgenic group.The transgenic IE09S034,double resistance 12-5,and C0030.3.5 materials had no significant influence on the body length,body weight,survival rate,larval development period,oviposition rate and oviposition amount of A.chinensis which indicates that transgenic materials has no negative effects on the predators in the food chain.