Target-invariant aggressive display in a tephritid fly

• We quantified the wing display of tephritid fly against male and female conspecifics and jumping spiders.
• Display rates and bout durations did not differ against spiders or flies.
• Flies were more likely to walk away or fly away after displaying to spiders.
• Other display characteristics remained similar between treatments.
• We suggest that fly display to spiders is not driven by predator recognition.

Fruit flies of the family Tephritidae (Diptera) use specialized wing displays in aggressive encounters with conspecifics and predators. These displays, called supination displays, have been thought to deter attacks from one of their main predators, spiders of the family Salticidae. However, there is no information whether the display is qualitatively or quantitatively different when the target is a conspecific or a predator. In this study, we sought to determine whether flies vary their displays depending on the display target. Using the Mexican fruit fly Anastrepha ludens, we compared the characteristics of the display that male and female flies use against conspecifics and spiders. Flies did not distinguish between spiders and conspecifics in terms of display rates and bout duration. In general, flies are more likely to retreat faster from spiders after performing a display. We suggest that supination is a generalized aggressive behavior that is independent of the target.