Turning lances into shields: Flower mantids stretch their raptorial forelegs to avert and deflect predator attack

Evolutionary co-option, in which existing traits acquire novel adaptive functions, is a key strategy by which organisms adapt to new environmental challenges. Although such co-option has been widely documented at the genetic and morphological levels, its incidence at the behavioural level remains largely unknown. Mantids stretch their forelegs to capture prey; however, some flower mantids also perform foreleg stretches in the absence of prey. The current study tested whether this behaviour represents a novel function of the foreleg stretch, thus representing a case of behavioural co-option. Predator encounter behaviour assays revealed that foreleg stretching facilitates the escape of flower mantids from large predatory mantids by delaying predator approach or deflecting their attack towards less vulnerable body parts. Phylogenetic analysis suggested that the ancestral function of foreleg stretching involves prey capture, with the anti-predator function subsequently acquired in the flowe..., Predator encounter assay
 
We performed predator encounter assays using 4th instar nymphs of the flower mantid Astyliasula basinigra (n = 26) as the model and 4th instar nymphs of the large-sized mantid Rhombodera longa (n = 9) as the predator.Results showed that:
 
(1) Foreleg stretching behaviour enhanced the survivor possibility of the flower mantids under predation risk.
 
(2) Foreleg stretching can significantly delay and reduce predator attacks, likely by intimidating the predators or confusing predatory mantids regarding the target location.
 
(3) Foreleg stretching can deflect predators’ attacks from the more vulnerable body trunk to the less vulnerable forelegs, thereby facilitating escape after the attack.
 
Characterising the types of foreleg stretching behaviours
 
We compared the stretching behaviour among three flower mantid species: A. basinigra, Pseudocreobotra wahlbergii, and Acromantis hesione. Type I is characterised by the alternative ex..., , # Turning the lances into the shield: Flower mantids stretch raptorial forelegs to avert and deflect predator attack

[https://doi.org/10.5061/dryad.3xsj3txq1](https://doi.org/10.5061/dryad.3xsj3txq1)

Contact Yuanlang Li ([[e-mail]](mailto:[e-mail])) with any questions. This manuscript has been accepted for publication at Proceedings of Royal Society B.

Li Y, Liu Q, Chen Z, Liang L, Wang Z, Duan Y, Song F, Cai W, Ge J, Li H, Tian L. Turning lances into shields: flower mantids stretch their raptorial forelegs to avert and deflect predator attack. *Proc. R. Soc. B* (accepted). 10.1098/rspb.2024.3081

## Description of the data and file structure

### Files and variables

#### File: DataS1.csv

**Description:** Data from *Predator encounter assay*, including normal groups and manipulated group.

##### Variables

* Predator IDs: Predator identity number
* Flower mantid IDs: Flower mantid identity number
* If stretching: Flower mantid stretching or not
* Targets: Predato...,