REDIA (2002) 85, 111-119

A. Raspi, E. Iacono and A. Canale (2002)
Variable photoperiod and presence of mature eggs in olive fruit fly, Bactrocera oleae (Rossi) (Diptera Tephritidae)
REDIA 85, 111-119
Abstract: Adults of B. oleae were submitted to different photoperiodic treatments. Treatment duration was a fixed term of 15 days after emergence. In each of the photoperiodic treatments, 3 different daily increases/decreases in the photophase of the first two days of treatment were chosen (15 min increase/decrease from the very first day, 60 min increase/decrease the first day or 60 min increase/decrease for the first two days); for the remaining days of treatment, the daily increase/decrease was 15 min.
The results obtained by the photoperiods with initial 12:12 (L:D), both for the increasing and decreasing photophase, showed that independently of the 3 daily increases/decreases chosen these photoperiods had an inhibiting effect on the eggs maturation. Thus only a small percentage of females was found to have mature eggs (from 17.3% to 27.9%) and the mean number of eggs/female was low (from 3 to 7.2). The results obtained by the photoperiod with initial 9:15 (L:D) and increasing photophase and by the initial 15:9 (L:D) with decreasing photophase showed that, independently of the 3 daily increases/decreases chosen, these photoperiods induced egg ripening in almost the totality of females (from 88.2% to 98.3%) and the mean number of eggs/female was high (from 10.6 to 16.3). The results obtained with the variable photoperiod treatments having as their initial photoperiod 9:15 (L:D), 11:13 (L:D) and 13:11 (L:D), characterised by increasing photophase, and with the treatments 11:13 (L:D), 13:11 (L:D) and 15:9 (L:D), characterised by decreasing photophase, allow the following statements to be made:
- the transition from the pbotoperiod 12:12 (L:D) (21st March and 23rd September) plays a major role to induce or to inhibit eggs maturation, as the shift from 12 causes an inversion in the photoperiodic trend;
- the percentage of females that ripen eggs and the mean number of eggs per female were related with the number of days during which females are exposed to the photoperiodic trend stimulating eggs maturation.
The results are well in line with field observations and clearly corroborate the finding that the olive fruit fly presents two periods of reproductive diapause, regulated by the photoperiod, one in the spring and the other in autumn, In nature females with eggs can be found throughout April and throughout October, although during the latter periods the females are already in reproductive diapause.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Database assignments for author(s): Angelo Canale

Research topic(s) for pests/diseases/weeds:
general biology - morphology - evolution
population dynamics/ epidemiology

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Bactrocera oleae