Metal accumulation by ceratitis capitata (diptera) and transfer to the parasitic wasp coptera occidentalis (hymenoptera)

« Accumulation of lead (Pb), cadmium (Cd), and copper (Cu) (from food) by the fruit fly (Ceratitis capitata Wiedemann ; Diptera, Tephritidae) and the transfer of the metals to the internal solitary pupal parasitoid Coptera occidentalis Muesebeck (Hymenoptera, Proctotrupoidea, Diapriidae) were investigated expermentally by exposing host larvae to contaminated diets. Each metal was added to the diet at two concentration : Cd, 50 and 100 µg/g ; Pb and Cu, 400 and 800 µg/g diet dry weight. Whole-body concentrations of applied metals and of zinc (Zn) int the host and parasitoid were determined by atomic absorption photospectrometry. Concentration factors (CFs) for all metals (based on initial dietary concentrations) were lower at the higher food contamination level. Cadmium (CF=3,2-7,05) and Zn (CF=2,79-7,05) were accumulated by fruit fly larvae more efficiently than were Pb (CF=0,95-1,02) and Cu (CF=0,35-0,78, except control : 37, 2). Considerable quantities of the metals taken up by host larvae and retained in their pupae were eliminated via the meconium after eclosion of flies (Cd, 33% ; Pb, 33-51% ; Cu 24-1,4% to pupae and adults, respectively, depending on the applied metal). The remaining amounts of the metals were detected in the host puparia that remained after wasp eclosion. Vitaly and fecundity of the parasitoid were not impaired by host metal contamination. Thus, the parasitic wasp probably possesses an efficient regulatory mechanism that mediates excretion of toxic metals before pupation and that diminishes the potentiel hazard of high metal loads in the host. »