Mortality and tissue damage by heavy metal contamination in the German cockroach, Blattella germanica (Blattaria, Blattellidae)

The accumulation of lead, cadmium, mercury, and chromium, supplied in the d iet under experimental conditions. was studied in adult German cockroaches. Chronic heavy-metal exposure determined different rates of mortality highe r in males than in females. In both sexes, Hg, Pb, and Cr bioaccumulated in rime, whereas Cd remained at constant low concentrations. Histological stu dies showed that in some organs and structures. such as the ovary, the test is, the alimentary canal and the fat bodies, there were profound and irreve rsible pathological anomalies in their tissues. Also the embryos of some tr eated females suffered heavy damage during development, and the symbiotic r elationships between bacteria and fat body cells were deeply altered.