Take-off mechanisms in parasitoid wasps

Abstract

High-speed video analyses of the natural behaviour of parasitoid wasps revealed three strategies used to launch the insects into the air. Which strategy is the most energy efficient? In , 92% of take-offs by were propelled entirely by movements of the middle and hind legs, which were depressed at their coxo-trochanteral and extended at their femoro-tibial joints. The front legs left the ground first, followed by the hind legs, so that the middle legs provided the final propulsion. Second, in other species of a similar mass, and , all take-offs were propelled by a mean of 2.8 and 3.8 wingbeats, respectively, with little or no contribution from the legs. The first strategy resulted in take-off times that were four times shorter (5 versus 22.8 ms) and take-off velocities that were four times faster (0.8 versus 0.2 m s). Calculations from the kinematics indicate that propulsion by the legs was the most energy-efficient strategy, because more energy is put into propulsion of the body, whereas in take-off propelled by repetitive wing movements energy is lost to generating these movements and moving the air. In heavier species such as and, take-off was propelled by the combined movements of the middle and hind legs and wingbeats. In , this resulted in the longest mean take-off time of 33.8 ms but an intermediate take-off velocity of 0.4 m s In all three strategies the performance could be explained without invoking energy storage and power amplification mechanisms.

Effectiveness and efficiency of two distinct mechanisms for take-off in a derbid planthopper insect

“…contractions of muscles in its middle and hind legs without the need for a catapult mechanism, this form of take-off is also more energetically efficient than that of other wasps of similar mass that use wing beating to generate take-off (Burrows and Dorosenko, 2017b).…”

Three‐Legged Locomotion and the Constraints on Limb Number: Why Tripeds Don’t Have a Leg to Stand On

“…For example, ghost crabs and octopuses have multiple appendages and can utilize a wide range of locomotion types, including bipedalism, where only a single pair of arms is used. [6,7] Therefore, if any animal were to employ only three appendages during locomotion, regardless of the total number it has, that form of locomotion would appropriately be called tripedalism (or tripedality) and the animal may be considered tripedal. However, to be considered a true triped, the animal must only have three legs in total with which it can locomote.…”

“…[43] Insects are not the only multilegged arthropods that utilize the tripod gait; horned ghost crabs have also been observed to use it. [6] There are many vertebrates in which the tail essentially functions as a third or an even fifth appendage. Because of their highly specialized and elongated hind feet, bipedal walking for some macropods (e.g., kangaroos) is difficult and highly inefficient.…”

The effect of air resistance on the jump performance of a small parasitoid wasp,Anagyrus pseudococci (Encyrtidae)

“…It can serve the purpose of passing over obstacles (Fleagle, 1976;Kohlsdorf and Navas, 2007), escaping from predators (Burrows and Dorosenko, 2014;Suter and Gruenwald, 2000), capturing prey (Jackson and Pollard, 1996), righting the body (Evans, 1972;Frantsevich, 2004;Ribak and Weihs, 2011) and even 'hitchhiking' on a larger organism ( phoresy) as a means of dispersal (Fatouros and Huigens, 2012;Houck and O'Connor, 1991). In addition, many flying animals jump into the air as part of the flight initiation (take-off ) process (Burrows and Dorosenko, 2017;Card and Dickinson, 2008;Earls, 2000;Heppner and Anderson, 1985;Kutsch and Fuchs, 2000;Ribak et al, 2016). The energy required to move the body in the air during a jump is generated at take-off as the jumper pushes against the ground.…”

“…With a body length of less than 1 mm in some species, small parasitoid wasps provide an interesting research model with which to examine the constraints associated with body miniaturization. Jumps are routinely executed as the flight initiation mechanism of several parasitoid wasps (Burrows and Dorosenko, 2017), including the Anagyrus pseudococci species (Fig. 1) studied here.…”