The Potential Effects Of Six Bt Proteins On Apolygus Lucorum And Its Predatory And Parasitic Enemies

In 1996,genetically modified(GM)crops were firstly commercialized in 6 countries with 1.7 million hectares,and in 2016,the first year after the second decade of commercialization of GM crops,GM crops were grown by 26 countries with 185.1 million hectares.It is noteworthy that the worldwide grown area of GM crops with insect-resistant(IR)traits expressing insecticidal proteins derived from the soil bacterium Bacillus thuringiensis(Bt)accounted for 41% of the total global planted area of GM crops in 2016.Undoubtedly,the cultivation of insect-protected crops has delivered several economic and environmental benefits,like effective suppression of economically important pests,increased yield,reduced application of broad spectrum synthetic insecticides and the resurgence of beneficial insects.However,in addition to these benefits,IRGE crops also have brought some serious problems,like evolution of Bt resistance and pose potential adverse effects on their non-target organisms.In China,the planting of Bt cotton provides excellent control of Helicoverpa armigera,but fail to control the mirid bugs.Therefore,some mirid bugs,like Apolygus lucorum has emerged as an important economic pest in this low spray environment conferred using Bt cotton.Nowadays,the main management tactic for the control of mirids is the application of broad-spectrum synthetic pesticides,but few insecticides can effectively and sustainably suppress the outbreak of mirids without causing any resistance,health and environmental problems.Thereby seeking for new ways for controlling the frequent outbreak of A.lucorum is urgently needed,like developing new transgenic crops with resistance to mirids.Last year,a new developed cotton variety expresses a Bt crystal protein,Cry51Aa2,that is toxic to mirid bugs.Although the commercial use of this variety is still unknown,the development and application of transgenic crops with resistance to mirids would greatly benefit worldwide agriculture.Thus,the development of dietary exposure assays for assessing the toxicity of insecticidal compounds to A.lucorum and its predatory and parasitic enemies is necessary before realease the transgenic crops with resistance to mirids in one country.Basing on the requirements of Tier-1 assay in the non-target risk assessment of insect-protected crops,we developed dietary exposure assays for assessing the potential toxicity of insecticidal compounds to A.lucorum and its parasitic enemy Peristenus spretus.Then we used the experimental systems assessing the toxicity of Cry1 Ab,Cry1Ac,Cry1 F,Cry2Aa,and Cry2 Ab proteins,which have been transformed into several crops,against A.lucorum and Peristenus spretus.In addition,we also used the dietary exposure assays developed previously assessing the potential toxicity of the five Cry proteins on Harmonia axyridis and Chrysopa pallens,which are two main predatory enemies of A.lucorum.In the tri-trophic bioassays,we used the insects that are insensitive to the test Cry proteins as the prey or the host of the predatory and parasitic enemy to study the potential effects of the test Cry protein on the natural enemies of A.lucorum through tri-trophic bioassays.Finally,we used the developed dietary exposure assays evaluating the toxicity of novel protein Cry2 Ah on A.lucorum and its predatory and parasitic enemies.1: The results of the fitness of A.lucorum fed on the artificial diet demonstrated that the diet support the normal survival and development of A.lucorum.In the fitness bioassay,about 90% of the A.lucorum nymphs that were fed on this diet developed into adults,which was more than 80%.The concentration of PA in the exposure assay diet at > 4 ?g/g FW of diet and E-64 at > 2 ?g/g FW could used as suitable positive controls in the dietary exposure assay.Addition of single Cry toxins or combinations of Cry toxins to the exposure assay diet with high concentration did not significantly affect the development and the activity levels of some important digestive enzymes,detoxifying enzymes and antioxidant enzymes of A.lucorum.2: The potential influence of the five Cry proteins on H.axyridis and C.pallens were assessed using the dietary exposure assays developed previously,and the results showed that the test Cry proteins did not negatively affected the development or the test enzyme activities of H.axyridis and C.pallens.When H.axyridis and C.pallens preyed on insects that had fed on artifical diets containing Cry toxin,the development of H.axyridis and C.pallens were not significanlty affected.3: The concentration of E-64 in the honey solution at > 2 ?g/g FW could be used as suitable positive control in the dietary exposure assay of P.spretus.Feeding of single Cry toxins or combinations of Cry toxins did not significantly affect the adult longevity and total fecundity of P.spretus,as well as the test digestive,detoxifying and antioxidant enzyme activities in P.spretus.Furthermore,the development and survival of P.spretus larvae and pupae were also not significantly affected when using A.lucorum that fed on diets containing different Cry proteins as the host.4: The potential toxicity of novel protein Cry2 Ah on A.lucorum,H.axyridis,C.pallens and P.spretus were evaluated using the dietary exposure assay system developed above,and the results indicated that ingestion of Cry2 Ah at high concentration did not significantly affect the development and the test digestive,detoxifying and antioxidant enzyme activities of the four insects.