Artificial diet alters activity and rest patterns in the olive fruit fly

Olive fruit flies, Bactrocera oleae (Diptera: Tephritidae) reared in the laboratory on an artificial diet are essential for the genetic control techniques against this pest. However, the colony's laboratory adaptation can affect the quality of the reared flies. We used the Locomotor Activity Monitor to track the activity and rest 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. Bouts of inactivity with duration longer than five minutes were considered a rest episode. Locomotor activity and rest parameters were found to be dependent on sex, mating status and rearing history. In virgin flies reared on 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 female olive-reared flies. Laboratory flies reared on artificial diet had lower locomotor activity levels during the light period and more rest episodes of shorter duration during the dark period compared to flies reared on olives. We describe the diurnal locomotor activity patterns of B. oleae adults reared on olive fruit and on artificial diet. We discuss how locomotor activity and rest pattern differences may affect the laboratory flies' ability to compete with wild males in the field.