Trophic structure and function in the larva of predatory muscid flies (Diptera, Muscidae)

摘要

Assessed multiple times over a 100-year period, yet poorly understood, we provide a new view of trophic structure and function in predatory muscid larvae based on Phaonia goberti (Mik) and Phaonia subventa (Harris) (Diptera, Muscidae). Trophic structure and function were investigated by morphological analysis, direct observation and filming. Larvae search for prey using a compartmentalised body. The rear compartment grips the substrate, while the middle one turns to the sides and the front one grabs prey. Two feeding mechanisms were recorded, sucking and lunging. Sucking occurs when the head is anchored inside the prey, and fluids are ingested using the pump in the head skeleton. Lunging is the head moving forwards and backwards, coordinated with lowering and raising of the mandibles during which fluids and tissue are gathered into the cup-shaped, oral cavity prior to sucking in. These mechanisms rely on prey being pierced, and this is achieved by a remarkable structural and functional partnership between the pseudocephalon, mandibles and accessory sclerites. The partnership involves tightening the integument of the prey between the oral bars and disengaging the mandible hooks to pierce it. Due to connections between the oral bars and pseudocephalon, the hooks do not extend from their sheaths except when piercing, an unusual feature in larvae of the Cyclorrhapha (Diptera).