I want to detect signals of death in a insect tissue, it is possible do that with propidium iodide, I have seen that people used iodide with culture cells.
Technically, I think propidium iodide can't permeate living cells, so I guess if you add the stain and you see red it means they're dead? I've only used it to stain nuclei after fractionation of cells but it can also be used to stain DNA.
Propidium Iodide is often used as a dead cell marker.
It is a trication and thus cannot cross intact membranes.
It is then used for the detection of late stages of apoptosis.
In plant biology we also use PI as a cell wall stain. Maybe it will also stain chitine in insect tissue.
If you plan to use it on live tissue it may work, but there's no warranty. On live cells the membrane will appear fluorescent. In dead cells it is the nuclei that will fluoresce.
PI is usually used, with Anexin V, to detect early stage apoptotic cells (not late). The Anexin V stains the exteriorized phosphtidyl serines while the PI stains the DNA of cells with damaged cell (and nuclear) membranes. So, Anexin V positive PI negative cells have exteriorized phosphatidyl serines (a very early event is apoptosis) with intact cell (and nuclear) membranes. Cells positive for both have damaged cell membranes (so Anexin V and DNA are available for staining). Double negative cells are healthy with intact membranes (so no PI staining and no Anexin V staining). As noted by Katherine French, above, fluorescein diacetate (FDA) is a good stain for viable cells. It is abosrbed by cells and metabolized by healthy cells into a monoacetate that is trapped inside the cells, so with prolonged follow-up, one can see increasing stain intensity in the healthy cells.