Neighbor density and post-contact immobility duration as antipredator behavior: Antlion larvae do not fit the selfish prey hypothesis

Remaining immobile for an unpredictable period after being touched by a potential predator (post-contact immobility, PCI) may favor survival. However, the factors that determine variation in PCI duration are poorly understood. We tested whether PCI duration depends on the surrounding conspecific density (the selfish prey hypothesis) in the tropical antlion larvae Myrmeleon crudelis. These insects avoid predation by being immobile or burying themselves. The selfish prey hypothesis predicts a reduction in the PCI duration as conspecific density increases because this high density of conspecifics around can stimulate the redirection of the predator's interest in other nearby potential prey. In the field, we measured PCI and found that its duration was independent of the conspecific density. We also measured the PCI of a subset of larvae in a density-reduction lab experiment. We found that larvae displayed shorter PCI duration when we reduced their number of neighbors to zero. These results..., Field observations
We randomly selected 103 focal antlion pits (1-5 cm in diameter) and placed a 25 x 25 cm square plot with the selected focal pit at the plot center. Next, we counted the number of traps inside the plot and measured the pit diameter of all of them with a digital Caliper to the nearest 0.1 mm. We calculated the density of conspecifics around the focal pit (i.e., # of pits/625 cm2) and the total area of the surrounding pits (i.e., the sum of the area of all pits inside the plot excluding the focal larva’s area). The area of each pit was estimated using the formula of π * r2.
We measured PCI duration as the difference (in seconds) between when the antlion landed on the substrate and when its body moved for the first time. We extracted the focal larva from the ground by gently scooping the soil in the trap ~5 cm deep with a spoon. We placed the spoonful on a plastic kitchen sifter to locate the larva. Once located, we held it dorsoventrally with entomological forceps to si..., , # Antlion larvae post-contact immobilization duration

[https://doi.org/10.5061/dryad.2bvq83c0v](https://doi.org/10.5061/dryad.2bvq83c0v)

## Description of the data and file structure

ReadME Antlion data - selfish prey

FILE: “antlion data selfish prey.csv”

OVERALL DESCRIPTION: 

This file contains the data of the post-contact immobilization (PCI) duration in seconds of different antlion larvae measured in the field and a subset measured in the lab.

COLUMN EXPLANATION:

Phase: Denotes the source of data: Either “Field_observations” or the “Lab_experiment”. A subset of larvae were tested in both conditions.

Individual: The individual ID code for each larvae.

Pit_diameter_cm: The diameter of each of the antlion larvae in the field was measured to the nearest 0.1cm with calipers.

Number_of_neighbors: The total number of other antlion larvae with active pits in a 25x25 cm square plot surrounding the focal larvae pit.

Post_contact_immobilization_PCI_s: The difference (in seconds) bet...