Preliminary trials for a continuous rearing of Bactrocera oleae (Rossi) on its natural host Olea europaea L. in laboratory and future perspectives
Abstract: A simple and affordable small-scale rearing technique to supply olive fruit fly (Bactrocera oleae Rossi) instars continuously throughout the year, even when fresh fruits are not available naturally to oviposit, is essential to optimize biological studies. Olive fruits came from a typical olive grove of northern Lazio (Cura di Vetralla, VT, central Italy), organically managed. Cages, feeders and instruments were specially designed. The fruits were kept fresh for more than 1 year in special “muffs” of straw and tulle, assembled directly on fruiting branches. The rearing started in 2005, as soon as emergences occurred. Adults were collected from the field and moved to the rearing cages with a bunch of sound and fresh fruits, to allow egg laying. Thereafter, every time a new lab generation started emerging, a bundle of fresh fruits was moved from the field into the cages to let new ovipositions occur. Temperature and RH were maintained at standard lab conditions, 20°C ± 2°C, 60% ± 5% RH, and natural photoperiod. From 11 October 2005 to 22 January 2007, the fly gave 13 continuous reproductive cycles in the lab, 1 generation every 40 days on average. An exception was the 9th generation (27 August-27 September) which lasted 31 days because of accidental high temperatures (26-27°C). This is the first method which has succeeded in obtaining olive fly generations continuously on its natural host. Fine tuning this technique will make it suitable for every other study (i.e. physiological, biological and behavioural studies, parasitoid rearing and release, sterile insect technique, etc.).