HOST-PARASITOID RELATIONSHIP OF CERATITIS-CAPITATA (DIPTERA, TEPHRITIDAE) AND COPTERA-OCCIDENTALIS (HYMENOPTERA, PROCTOTRUPOIDEA, DIAPRIIDAE) UNDER HOST HEAVY-METAL STRESS

The development and fecundity of Ceratitis capitata Wiedemann (Diptera : Tephritidae) and the host-parasitoid relationship of C. capitata and its pupal endoparasitoid, Coptera occidentalis (Muesebeck) (Hymenopte ra: Proctotrupoidea: Diapriidae) were investigated under conditions in which the host was stressed by heavy metal ingestion. C. capitata lar vae (from first instar to pupation) were fed diets that were separatel y contaminated with three metals; each contaminant was applied at four concentrations that differed by a factor of 2. The lowest concentrati ons were as follows: copper 100 mu g/g, cadmium 25 mu g/g and lead 100 mu g/g diet dry weight (dw). Larval development, pupation rate and pu pal weight of the fruit fly were negatively affected by increasing met al concentrations. Metal concentrations of 400 mu g Cu, 50 mu g Cd and 400 mu g Pb/g diet dw were selected for studying reproductive perform ance of C. capitata and parasitisation rate, development and reproduct ion of C. occidentalis. Oviposition, actual fecundity and hatching rat es of C. capitata were not significantly influenced by metal contamina tion. The parasitoid did not discriminate between metal-contaminated a nd control fruit fly pupae. Parasitisation rates were similar in all t reatments (64.6-65%). Heavy metal induced stress of the host altered n either the parasitoid developmental rate nor the proportion of females in parasitoids that emerged from contaminated pupae. Life span and re productive performance of C. occidentalis females that emerged from me tal-stressed hosts were not significantly different from control femal es. However, a significantly lower percentage of females emerged from copper-and cadmium-contaminated hosts. In groups contaminated by 400 m u g Cu, 50 mu g Cd and 400 mu g Pb/g diet dw, whole body concentration s of the respective metals were determined in pupae and imagines of C. capitata and imagines of C. occidentalis.