Abstract:

The influence of urban air pollutants SO₂ and Pb on the Comstocki mealybug's population density in Ginkgo biloba (Linn.)and Fraxinus Chinensis (Roxb.) were stuidied in Taiyuan City.The accumulated contents of environmental air pollutants SO₂ and Pb in the bodies of the scale insects, their host trees and natural enemies were determined by the method of analytical chemistry.The results showed as follows: 1.Pseudococcus comstocki (Kuwana) could parasite on Ginkgo trees,and brought about damage severely was found for the first time. 2.The Air pollutants,sulphur dioxide and lead,were absorbed and then accumulated in the bodies of the scale insects,their natural enemies,and the host trees (Ginkgo and Fraxinus)。 3.The Air pollutants,sulphur dioxide and lead could promote the development of Pseadococcus comstocki compared with the light polluted areas,oviposit period in the heavy polluted area was moved up 2～3d,oviposit amounts increased by 20.7～29.4 Ova/each in G.biloba and 32.5～49.9 Ova/each in F.chinensis. 4.The Air pollute level,pollutants contents in the bodies of the host trees were positively correlated with scale insect population density (SIP). The greater pollutants contents of host trees,the greater its SIP was. 5.The heavy pollution environment had changed the amino acid component of the trees. In the bodies of G.biloba the content of 13 amino acid component was increased by 24.4%～76.19%;the total carbohydrate and soluble carbohydrate were increased by 1.78% and 6.46% respectively. 6.Pseudococcus comstocki could develop largely in the pollution environment, the responsible reasons could be the weaken resistance of the host tree,the reduction of natural enemies and the improvement of scale insect tolerance.

Key words: Air pollution, SO₂, Pb, Pseudococcus comstocki, Ginkgo biloba, Fraxinus chinensis