Bioconcentration effects of Cd, Pb and Zn in soil-Eupatorium adenophorum Spreng-Procecidochares utilis Stone system

Procecidochares utilis Stone is an obligatory parasitic natural enemy widely used to control the highly invasive Eupatorium adenophorum Spreng plant. However, parasitic rate of P. utilis in E. adenophorum has significantly decreased in mining areas polluted with heavy metals. To study bioconcentration effects of Cd, Pb and Zn in soil-E. adenophorum-P. utilis system, soil, E. adenophorum and P. utilis samples were collected at the Lanping Lead-Zinc Mine in Yunnan Province using the concentric circles method. The samples were then analyzed for Cd, Pb and Zn contents. The results showed that Cd, Pb and Zn contents in soil-E. adenophorum-P. utilis system significantly declined from the center outwards. The ranges of bioconcentration factors of Cd, Pb and Zn in the soil-E. adenophorum system were 0.205~0.614, 0.058~0.079 and 0.222~0.398 with corresponding averages of 0.453, 0.067 and 0.315, respectively. The bioconcentration factors of Cd, Pb and Zn in the E. adenophorum-P. utilis were 1.06~7.69, 9.68~20.13 and 1.13~1.56 with corresponding averages of 2.47, 12.83 and 1.42, respectively. Pb was more easily absorbed than Cd and Zn. The results confirmed that Cd, Pb and Zn could be transferred and bioaccumulated in soil-E. adenophorum-P. utilis system. This mainly expanded the mode and trend of heavy metal transfer from soil to E. adenophorum to P. utili. This finding was also helpful in enriching the eco-toxicological effects of heavy metal pollution. It further strengthened the basis for future studies of the mechanism of heavy metal stress control effects on P. utilis.