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

Abstract

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.

The Roles of Mating, Age, and Diet in Starvation Resistance in Bactrocera oleae (Olive Fruit Fly)

“…Male C. capitata that courted but did not mate have a similar lifespan to those that courted and then mated, meaning that courtship alone is metabolically costly [50]. It was also found that mating decreased the locomotor activity levels of males; these findings provide evidence that both courting and mating are metabolically costly [36]. Males may need to compete for access to mates or invest in courtship displays.…”

“…Flies that had been kept with conspecifics of the opposite sex were monitored by a human observer to verify mating. We observed the flies for mating from 16:00 to 21:00 because, in this species, mate searching and courtship take place during the late evening [34,36]. Individuals that had not mated were removed from the experiment and were replaced with others that had mated.…”

“…A recent study on D. melanogaster showed that feeding adults a protein-based diet for twenty generations led to lower body weights and wing reductions in male adults [32], and the trade-off between reproduction and lifespan is still an area under investigation [33]. There are several studies on topics related to B. oleae regarding the physiology of the insect (e.g., the determination of volatile substances in olives and their effect on reproduction [34], mating competition between wild and artificially reared adults [35] and altered activity and rest patterns [36]), but, to our knowledge, starvation resistance in B. oleae has not yet been studied. Additionally, the only existing work in the literature addressing starvation resistance in Tephritidae that examines how aging and diet affect starvation resistance was conducted on virgin C. capitata [16], which is a polyphagous, cosmopolitan insect.…”

Locomotor Activity of Adult Olive Fruit Flies Recorded under Conditions of Food or Water Deprivation

“…Subsequently, we pooled the recordings from the three monitors to obtain the total activity, which represented the cumulative movements across all three monitors (a total of 1440 recordings: 840 during the daytime and 600 during the nighttime). Next, we calculated the mean value for each individual adult every two hours, following the approach described by Terzidou et al [7]. Based on these results, we constructed twelve radar diagrams per age group and type of stress.…”

“…Recent studies were conducted on B. oleae regarding the lifecycle [5] and how landscape affects insect movement [6]. Additionally, the difference in mobility between wild olive fruit flies and artificially reared insects was studied using a LAM25 system (locomotor activity monitor)-Trikinetics [7]. It would be very useful to expand such studies to the adults of B. oleae to investigate the effects of abiotic stress conditions such as food and water deprivation.…”