Method of attachment of pupae of Mansonia annulifera (Theo.) and M. uniformis (Theo.) to Pistia stratiotes

Abstract

Detailed studies are described, and illustrated by photomicrographs, of the method by which the newly emerged pupae of Mansonia annulifera (Theo.) and M. uniformis (Theo.), which are important vectors of filariasis in Kerala State, India, attach themselves to the aquatic plant Pistia stratiotes. After emergence of the cephalothorax through the ruptured larval skin, the latter continues to support the pupal abdomen while this doubles over so that the respiratory trumpets of the cephalothorax are directed towards and eventually reach the point of insertion of the larval siphon into the Pistia root. The trumpets are then plunged into the hole occupied by the larval siphon, which is almost simultaneously yanked out of it by the straightening of the pupal abdomen, leaving the pupa attached by its trumpets. The pupa casts off the larval skin posteriorly and then curls round to assume the usual comma shape. The entire process occupies under one minute in M. annulifera and 3–6 minutes in M. uniformis.