Bimanual Food Manipulation by Locusts Feeding on Loose Food

摘要

Holding food bimanually for biting off pieces with the mouth is a behavior performed by several groups of insects with predatory or plant eating habits. Locusts often grab longer pieces of loose or dangling grass with their forelegs and eat it in repetitive movement patterns by holding the blade vertical between the opposed tarsal pads. Head and body remain still while the mouthparts bite off and ingest suitable pieces. The forelegs alone raise and guide the grass blade precisely between the mandibles that bite across it in series of 1-5 consecutive biting bouts. A typical series has 3-4 bouts and cuts a 5-7mm wide blade completely. The remaining edge of the grass blade is skewed at about 30-60 degrees. Consecutive series start with biting into the upper edge of the blade after the forelegs have pulled it nearer and under the mouthparts. During the first bites both legs extend forward moving the opposed tarsi along the blade and renew their grip more outward. The whole stereotyped but adaptive pattern involves only forelegs and mouthparts, while the palps continuously monitor the food's shape and relative position to the mouthparts. In this first study of bimanual (bi-tarsal) food handling in insects the standard sequence of movements and muscle coordination of the forelegs is described for locusts. This repetitive behavior is an example of object-centered coordination between several appendages within the peripersonal space of animals.