A predator's response to a prey's deterrent signal changes with experience.

Prey signalling to predators is an attempt to divert or nullify an attack even before it occurs. If these signals are backed up by a potent defence, then the likelihood of the predators learning to avoid them is high. In species that use deceptive signalling, predators could learn to overcome such a display and diminish the efficacy of the display. We studied the effect of experience on the efficacy of tephritid fly displays against jumping spiders. We compared attacks on displaying flies, non-displaying flies, and two other prey species (a facile prey and a prey with a defence). Spiders were more likely to attack displaying flies over time. However, spiders that were familiar with the fly appearance but not display also increased their attack rates. We suggest that spiders attend to both components of the fly display, i.e. motion and appearance, but with motion cues taking priority.

The effect of irradiation and mass rearing on the anti-predator behaviour of the Mexican fruit fly, Anastrepha ludens (Diptera: Tephritidae).

Fruit flies (Diptera: Tephritidae) are major pests worldwide. The sterile insect technique, where millions of flies are reared, sterilized by irradiation and then released, is one of the most successful and ecologically friendly methods of controlling populations of these pests. The mating behaviour of irradiated and non-irradiated flies has been compared in earlier studies, but there has been little attention paid to the anti-predator behaviour of mass-reared flies, especially with respect to wild flies. Tephritid flies perform a supination display to their jumping spider predators in order to deter attacks. In this study, we evaluated the possibility of using this display to determine the anti-predator capabilities of mass-reared irradiated, non-irradiated flies, and wild flies. We used an arena setup and observed bouts between jumping spiders (Phidippus audax Hentz) and male Mexican fruit flies (Anastrepha ludens Loew). We show that although all flies performed a supination display to their predator, wild flies were more likely to perform a display and were significantly more successful in avoiding attack than mass-reared flies. We suggest that this interaction can be used to develop a rapid realistic method of quality control in evaluating anti-predator abilities of mass-reared fruit flies.