Abstract:

The effects of sulfur dioxide pollution from local factories to the outbreak of Diprion.jingyuanensis Xiao and Zhang were studied. Simulated pollution experiment in laboratory indicated that mean relative growth rate (MRGR) of D.jingyuanenisis larvae increased by 17% compared to CK, after they were fed with pine (Pinus tabulaeformis Carr.) needle which were fumigated by SO₂ (the highest concentration in a day was 255 μL) and the difference was remarkable (n=5,α=0.05,P=0.017). This revealed that the growth of D.jingyuanensis larvae could be enhanced after they were fed with contaminated needles in certain sulfur dioxide concentration. D.jingyuanensis in polluted area was easy to outbreak. Nevertheless, MRGR of D.jingyuanensis larvae was reduced by 8% compared to CK. after they were fed with pine needles which were fumigated by high concentration SO₂ (510 μL), and the difference was striking (n=5,α=0.05,P=0.01). High concentration of SO₂ seemed to hamper the growth of D.jingyuanensis larva. In the field the damage degree and cocoons density in polluted area was higher than non pollution area. In addition, the mechanism why SO₂ pollution was able to accelerate the outbreak of the sawfly was explored. The content of sulfur in pine needle in sulfur dioxide polluted territory was significantly higher than non SO₂ pollution area (α=0.05,P=0.09),but the content of nitrogen in needles at SO₂ polluted place was lower than non SO₂ pollution area.

Key words: Diprion jingyuanensis Xiao and Zhang, Pinus tabulaeformis Carr, Sulfur dioxide pollution, Mechanism