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

Abstract

The accumulation of lead, cadmium, mercury, and chromium, supplied in the diet under experimental conditions, was studied in adult German cockroaches. Chronic heavy‐metal exposure de termined different rates of mortality, higher in males than in fe males. In both sexes, Hg, Pb, and Cr bioaccumulated in time, whereas Cd remained at constant low concentrations. Histological studies showed that in some organs and structures, such as the ovary, the testis, the alimentary canal and the fat bodies, there were profound and irreversible pathological anomalies in their tis sues. Also the embryos of some treated females suffered heavy damage during development, and the symbiotic relationships be tween bacteria and fat body cells were deeply altered.

Key words:

• Blattella germanica
• Bioaccumulation
• Heavy metals
• Histology
• Endosymbiosis