Laboratory rearing alters activity and sleep patterns in the olive fruit fly

Abstract

Olive fruit flies, Bactrocera oleae (Diptera: Tephritidae) that are laboratory reared in artificial diet are essential for the genetic control techniques for this pest. However, the colony’s laboratory adaptation can affect their quality. We used the Locomotor Activity Monitor (LAM25, Trikinetics, MA, USA) to track the activity and sleep patterns of adult olive fruit flies reared as immatures in olives (F2-F3 generation) and in artificial diet (>300 generations). Counts of beam breaks caused by the adult fly activity were used as an estimation of its locomotor activity levels during the light and dark period. A longer than five minutes period of adults’ inactivity during the dark period was considered as one sleep episode. Activity levels and sleep parameters were found to be dependent on sex, mating status and rearing history. In virgin flies reared in olives, males were more active than females and increased their locomotor activity towards the end of the light period. Mating decreased the locomotor activity levels of males, but not of females olive-reared flies. Laboratory flies reared in artificial diet had lower locomotor activity levels during the light period and more sleep episodes of shorter duration compared to flies reared in olives. We describe the diurnal locomotor activity patterns of B. oleae adults reared in olive fruits and in artificial diet. We discuss how locomotor activity and sleep pattern differences may affect the laboratory flies’ ability to compete with wild males in the field.