The Malpighian tubules also contain two types of granules, calcium-containing granules and potassium containing granules. The second type of granule is mainly potassium with a larger quantity of organic matrix and is formed between the apical mircovilli. The idea of using insects as biomonitors can be very appealing. They are small active, fast growing animals that are abundant in number, occupy many different environments and are know to accumulate metals. In this review there are a number of factors raised to consider before using insect as biomonitors.
Some insects show large variability both temporal and spatial.
The ability to relate laboratory findings to those found in nature, along with differences in size, age, developmental stage and sex must be accounted for in order to understand the importance and effects of metal exposure. Summary Insects accumulate metals in the form of metal-containing granules which appear to enable the insect to tolerate exposure to metals. Storage-excretion to reduce the toxic effect of metals and metal reserves are two main purposes for formation of granules. However, research is still needed to gain a complete understanding of the mechanisms of metal uptake, metal tolerance and storage. References Brown, B.E. 1982.