Role of mosquito saliva in blood vessel location.

In order to ascribe a blood feeding function to the saliva of mosquitoes, we determined whether this secretion may limit the initial probing phase of biting behaviour. The probing of hosts was indeed prolonged when the salivary ducts were severed, but this prolongation was absent when mosquitoes were fed on an artificial meal contained beneath a membrane. In vitro, turbidometric assays demonstrated that saliva inhibits the ADP- and collagen-mediated aggregation of platelets. ATP and ADP were hydrolysed by saliva, and this apyrase activity explains, in part, the observed effect upon platelets. We conclude that the saliva of mosquitoes functions by facilitating location of blood vessels.