Abstract:

The effects of transgenic poplars to the structure of insect community was studied by the comparition of stands of transgenic and non-transgenic poplars.The study revealed that there was no much difference of insect and spider community between transgenic and non_transgenic poplar trees in an area of 1hm² while in 6.7hm² obvious difference of that was observed. Through the comparison of insect and spider community structures between pure transgenic poplar stand and 1∶1 mixed stand of transgenic and non_transgenic poplars, it was clear that Bt transgenic poplar could influence the insect community structure. In pure transgenic poplar stand, dominant species was Poplar Sawfly (Pristiphora benjingensis) while in mixed poplar stand was Poplar Prominent (Clostera anachoreta). To reduce the risky of being damaged by other non_lepidoptera defoliators resistant species to this kind of pest species should be used when Bt gene is transferred. The diversity and uniformity of pure transgenic poplar stand were higher than that of mixed transgenic poplars stand which leads to higher stability. However the density of Lady Beetles was 10 times higher in mixed transgenic poplar stand than that in pure transgenic poplar stand, averagely 0.21 per twig and 0.021 per twig respectively while the density of spiders in pure transgenic poplar stand was higher than that in mixed transgenic poplar stand, averagely 0.125 per twig and 0.0625 per twig respectively. Further study was needed in the effect of transgenic poplars to the non_target insects and natural enemies. The damage rate of pure transgenic poplar stand and mixed transgenic poplar stand were 11.26% and 18.48% respectively, the former was better but no significant difference.

Key words: Transgenic poplar, Bt, Non target species, Community structure