Motion-triggered defensive display in a tephritid fly

Abstract

Interactions between prey and predators are often mediated by signals sent by the prey. Passive signals such as aposematic coloration and active signals such as pursuit deterrence signals are thought to prevent attack from predators. In true fruit flies (Diptera: Tephritidae), the defensive wing display is called supination, and studies have shown that supination effectively reduces the chance of being attacked by salticid predators. In this study, we investigated the proximal causes of supination in staged interactions in an arena. We asked whether the movement of the display target influences the likelihood of triggering supination in the Mexican fruit fly Anastrepha ludens. We tested the effect of motion on fly display in three different ways using (1) a manually moved dead spider or beetle, (2) live bouts with a spider and a katydid and (3) video playback experiments where movement of the display target was controlled. Our results show that flies are more likely to perform supination when the display target moves. The identity of the display target did not influence display propensity, suggesting that the supination of flies is a generalised display behaviour against any possible threat.

A synthesis of deimatic behaviour

“…While ‘attacker’ often refers to a predator or competitor, it also extends to the range of natural enemies such as parasitoids, parasites, and micropredators ( sensu Lafferty & Kuris, 2002). Display initiation should coincide with the physical proximity of an attacker within some relevant distance – we suggest the phrase ‘display initiation distance’ ( sensu Aguilar‐Argüello, Díaz‐Fleischer & Rao, 2016) – and it will cease upon the perceived threat passing, such as when the attacker leaves the scene or obviously changes its motivation (e.g. from a focused attack to ignoring, or if the prey escapes the predator).…”