Kinematic analysis of the trophic apparatus of larval Chaoborus trivittatus (Diptera: Chaoboridae)

The functioning of the trophic apparatus of larval Chaoborus trivittatus Loew was recorded on film for the first time and is described. The feeding response was triggered by an acoustic signal in partly immobilized 4th-instar larvae. The cycle starts with the opening of the mandibles and the mandibular fans (mean duration = 0.11 sec), followed by an extension of the antennae (0.06 sec). After a pause of variable duration (0.04 to 0.25 sec), the antennae pull back (0.08 sec) and the mandibular apparatus scoops through the water toward the mouth (0.08 sec). The kinematics of the mandibular fans are suggestive of a filter-feeding action.