The venom of the tropical ctenid spider Cupiennius salei contains hundreds of components. We identified many of them (amino acid sequence, disulphide bridge structure, spatial structure) and analysed their activity on target structures such as insects, membranes or ion channels. The result of a venom injection into a prey item is a highly complex interaction between many components: a hyaluronidase destroys tissue, cupiennins perforate membranes, and neurotoxins inhibit ion channels. The activity of several of these components is synergistically enhanced by other components so that the overall dose needed is considerably minimized (Lucia Kuhn-Nentwig).
Among prey insects of C. salei dipteran flies are very sensitive, whereas some ant, beetle, or cockroach species need up to 4 log units more venom. The spider tries to invest its venom as economically as possible (venom optimisation hypothesis) and injects only the minimum amount needed. C. salei selects low-venom demanding prey items when its venom glands are empty and it is able to distinguish low- and high-venom demanding prey by smell (Wolfgang Nentwig).