| Transgenic corn expressing Bacillus thuringiemis cry1Ab or cry1Ac gene and B. thuringiensis insecticidal crystal protein were used for evaluating the effects of Bt to Pseudaletia separata Walker, Helicoverpa armigera Hubner, Locusta migratoria manilensis Meyer, Sitobion avenae, Galleria mellonella, Microplitis mediator Haliday in laboratory.1. Pseudaletia separata larvae were fed with Bt corn. The results indicated that the effects of Bt corn to P. separata were different with larval instar or varieties of Bt corn. The low instar worms were more susceptive to Bt corn. Compared with those fed with routine corn, the trend indicated that the weights of larvae fed with Bt corn were lower; the mortality rates of larvae were increased; the durations of larvae and pupal were prolonged, and pupal weights and eclosion rates declined; but no significant effects were observed that Bt corn to mature stage, number of eggs and hatching rate. Further studies indicated that Bt corn had antifeedant effect to P. separata. Analysis of hemolymph protein of the worms showed that the total hemolymph protein content of the worms fed with Bt corn was lower than that of the control. The results simplied that low hemplymph protein content might one of the factors leading to effects of Bt corn against P. separata. We also investigated host finding behavior of larvae, the results indicated that the neonates of P. separata were more attractable by the routine corn than Bt corn; but there was no significant difference on oviposition response of the female adult between Bt corn and the control. The honey-water containing B. thuringiensis crystal protein also had effects to the adult of P. separata, and the trend was that more higher the concentration was, more shorter the longevity of adult was.2. Bt corn had high lethal effect to Helicoverpa armigera. In the 6th day, mortality rates of 1st-instar and 3rd-instar larvae of H. armigera were 100% and 95%, respectively. Bt corn also had antifeedant effect to the worms of H. armigera. After they were fed with Bt corn, the dynamics of the larval weights decreased with the time going by and there was significant difference between the worms fed with Bt corn and routine corn. Analysis of hemolymph protein of the worms showed that the total hemolymph protein content of the worms fed with Bt corn was lower than that of the control; and feeding more time, this difference was more obvious.3. Locusta migratoria manilensis fed with Bt corn, its mortality rates were not obvious compared with the control. It indicated that the locusts were not susceptible to B. thuringiensis crystal protein. So, Bt corn field should pay attention to locust management. Further studies indicated that the total of hemolymph protein contents of the Locusta migratoria manilensis fed with Bt corn were lower than that in control within 72 hours; but as the time pass, the difference will diminish.4. Apterous or alate aphids of Sitobion avenae were artificially moved on Bt corn and routine corn. The results indicated that alate aphids of S. avenae had no preference to Bt corn and routine corn. The same result was also observed on apterous aphids of S. avenae. It suggested that Bt corncould not affect livability of S. avenae.5. The artificial diets containing B. thuringiensis kurstaki crystal protein(0.004ug/g~1600ug/g) had not significant effects on the larval duration, pupal weight, eclosion rate, mortality rate of Galleria mellonella. It suggested that G. mellonella was not susceptible to B. thuringiensis kurstaki crystal protein. As we know, at this time, the commercial Bt corns were mostly transferred gene from Bt subsp. kurstaki, and the total protein expressing in the pollen of Bt corn(MON810) was 0.09 ug/g(fresh weight). So, we concluded that Bt corn would not affect livability or development of G. mellonella. While analysed the hemolymph protein of the worms, we found that the total of hemolymph protein contents of G. mellonella fed with Bt corn were not different with the control within 2 days; ho... |
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