67-3 Friday, Jan. 5 14:00 - 14:15 Leaping larvae: hydrostatic jumpers at the mm-scale FARLEY, GM*; HARRISON, JS; WISE, MJ; SUTTON, GP; PATEK, SN; Duke University; Duke University; Roanoke College; University of Bristol; Duke University firstname.lastname@example.org
The elastic jumps of small insects are typically powered by elongate legs and accessory elastic structures; however, in earlier stages of development, many insect larvae have worm-like bodies without legs, potentially limiting their ability to disperse or escape predation. Here we present a kinematic and energetic analysis of a larval insect that can jump effectively without the use of legs and that instead uses hydrostatic control to launch itself into the air. We studied gall midge larvae (Cecidomyiidae: Asphondylia sp.) that form galls within the silverrod, Solidago bicolor. The midge larvae express this capability during only the final (third) instar within the gall. When extracted from the gall, they coil their body, brace their mouthparts against the tail, hydrostatically load their small bodies and then jump. During this process, a transient launching “leg” is formed from an otherwise worm-like body form. We analyzed the kinematics of their jumps off of a hard substrate (14 animals, 42 jumps, 1-7 jumps per individual). They accelerated on the order of 104 m/s2, with an average velocity of 1.1 m/s which is equivalent to approximately 350 body lengths/s. They traveled a horizontal distance of an average 27 body lengths and up to 40 body lengths. Our theoretical models suggest that environmental losses, such as drag, reduced jump distance dramatically in addition to energetic losses due to rapid body spinning. Surprisingly, our kinematic results align these small hydrostatic jumpers with the capabilities of the renowned elastic, legged jumps of fleas.