A STUDY ON THE ACCUMULATIONS OF URBAN AIR POLLUTIONS SO2 AND Pb IN THE BODY OF EULECANIUM GIGANTEA (S.)(COCCIDAE) AND THEIR HOST-PLANT SOPHORA JAPONICA
Abstract:The effect of urban air pollution on the populations of the scale insects,Eulecanium gigantea (Shinji) and E.kuwanai kanda in the planted street afforestation trees was studied in Taiyuan City from 1994～1995. The accumulative amounts of city air pollutants SO2 and Pb in the bodies of the soft scales and their host plant Sophora japonica were determined by the methods of analytical chemistry. The results showed as follows: 1.The scale insect population density (SIP) is positively correlated with the number of cars (Aut.No) driving in a certain district. The correlation equation is Y(SIP)=-30.508+0.0441X(Aut.No) and the correlation coefficient is r=0.895. The scale population density shows three undulatory levels, decreasing progressively from the city center to suburban districts.This regularity coincides with the gradient tendency of urban air pollution in the same area. 2.The contents of sulphur and lead in the body of the scale insects and their host plant are much higher in the polluted districts than that in the relatively clear districts, and the highest values are up to 1.92 g/kg and 6.80 mg/kg respectively. The accumulative amounts of pollutants are positively correlated with the automobile number. 3.Based on our study, it is suggested that Eulecanium gigantea and E.kuwanai can absorb and tolerate pollutants and that is an important mark on their resistance to city pollution. Futhermore, other reasons which result in the increasing number of scale insect are also discussed from the point of view of biological chain “scale insecthost plantnatural enemy” in the paper.