Predators must often employ flexible strategies to capture prey. Particular attention has been given to the strategies of visual predators that actively pursue their prey, but sit-and-wait predators have been largely overlooked, their strategies often characterised as stereotyped. Praying mantids are primarily sit-and-wait predators that often employ crypsis to catch their prey using a raptorial strike produced by their highly modified forelimbs. Here we show that the raptorial strike of the Madagascan marbled mantis (Polyspilota aeruginosa) varies in duration from 60 to 290 ms due to the tibial extension alone; slower strikes involve slower tibial extensions that may also be interrupted by a pause. The success of a strike is independent of its duration or the presence of these pauses. However, prey speed affects the duration of tibial extension and the probability of a pause occurring, both increasing at slower prey speeds. Adjusting the duration of the tibial extension according to prey speed allows mantids to time the final downward sweep of the tibia to their prey’s approach. The use of visual inputs to adjust the motor pattern controlling forelimb movements shows that not all aspects of the strike are stereotyped and that sit-and-wait predators can produce behavioural flexibility.

Madagascan marbled praying mantids (Polyspilota aeruginosa) [30] were purchased from a local supplier (BugzUK, Norwich, Norfolk, U.K.) and maintained in individual cages at the University of Sussex, U.K. They were fed with live crickets and maintained in a 12/12 hour light/dark cycle at room temperature (21-23°C).

To record strikes, mantids were placed on a black 10 x 10 cm cardboard platform, fixed on a 26 x 26 cm raiseable metal plate, in the middle of a 75 x 60 x 60 cm white arena illuminated from overhead. A target attached to a transparent fluorocarbon wire with a diameter of 0.16 mm (Airflo Fishing, Sightfree G3) was moved at constant speeds of either 200, 330, or 730 mm/s (referred to hereafter as slow, medium or fast prey speeds) near one end of the platform using a motor (MFA Como Drills, RE – 385). These speeds were representative of air speeds of flying insects such as fruit flies and blowflies. Targets were either 6 mm diameter dark plastic beads, blowflies or cricket nymphs ensuring the mantids were hungry whilst still being rewarded occasionally for hunting.

The animals were filmed through a circular aperture in the arena wall with a high-speed video camera (GC-PX100 JVC Ltd, Yokohama, Japan) at 200 frames per second. Analysis was performed offline using ImageJ (National Institutes of Health, Bethesda, MD, U.S.A.). The attacks were divided in phases based on femoral and tibial movements. The number of frames in each phase was then used to calculate duration. Joint angles were measured on the limb closer to the camera, either directly with the inbuilt angle tool, or limb segments were tracked using the MTrackJ plugin.

"Mantis" is a categorical variable identifying each animal. "Prey speed" is in mm/s. "Success" is a binary variable, 0 indicating failure in capturing prey and 1 indicating a successful capture. All other variables are in ms. "Approach" is the sum of "Extension" and "Pause". "Sweep" is the sum of "Thrust" and "Capture". "Strike duration" is the sum of "Approach" and "Sweep".