The experiments were conducted in the laboratory of Entomology and Agricultural Zoology of the University of Thessaly, Greece, during the autumn-spring of 2005–2006 at 25 ± 1 °C, 65 ± 5% r.h., and L14:D10 photoperiod, with the photophase starting at 07:00 hours. Light was provided by daylight fluorescent tubes with the intensity inside the test cages ranging from 1500 to 2000 lux.
We tested four medfly populations, originating from Brazil [Petrolina (lat: − 9.40, lon: − 40.49, host: Psidium guajava L. (Myrtaceae)], Portugal [Madeira (lat: 32.74, lon: − 16.98), host: Prunus persica (L.) Batsch (Rosaceae)], Kenya [Nairobi (lat: − 1.27, lon: 36.80), host: Coffea arabica L. (Rubiaceae)] and Greece [Chios (lat: 38.47, lon: 25.99), host: Citrus aurantium L.(Rutaceae)]. Pupae retrieved from field-infested fruits were transported by a courier agency to our laboratory. Because host fruit species may affect several biological parameters of the medfly (Krainacker et al., 1987 ), we reared all four populations for one generation under identical lab conditions and used the F1 progeny in our experiments. Rearing of wild flies was done by keeping adults in groups of about 100 individuals in wooden, wire-screened cages (30 × 30 × 30 cm) provided with water and a standard adult diet (YS) consisting of a mixture of yeast hydrolysate, sugar, and water at a 4:1:5 ratio. Females were allowed to oviposit into 5-cm hollow, red plastic hemispheres (domes) that were artificially punctured with 40–50 evenly distributed holes. Eggs were deposited on the inner surface of the dome. Each dome was fitted into a hole (5-cm in diameter) in the cover of a 5.5-cm plastic Petri dish. Water was placed in the Petri dish in order to maintain humidity levels beneath the dome to an adequate level for female oviposition (Boller, 1985 ). A plastic cup containing 0.5 ml of orange juice was also placed in the Petri dish to stimulate oviposition. Immatures were reared (same density of 50–100 eggs per food amount for all populations) on an artificial diet consisting of 200 g sugar, 200 g brewer’s yeast, 100 g soybean flour, 4 g salt mixture, 16 g ascorbic acid, 16 g citric acid, 3 g sodium propionate, and 1 l water (Boller, 1985 ).
We tested four medfly populations, originating from Brazil [Petrolina (lat: − 9.40, lon: − 40.49, host: Psidium guajava L. (Myrtaceae)], Portugal [Madeira (lat: 32.74, lon: − 16.98), host: Prunus persica (L.) Batsch (Rosaceae)], Kenya [Nairobi (lat: − 1.27, lon: 36.80), host: Coffea arabica L. (Rubiaceae)] and Greece [Chios (lat: 38.47, lon: 25.99), host: Citrus aurantium L.(Rutaceae)]. Pupae retrieved from field-infested fruits were transported by a courier agency to our laboratory. Because host fruit species may affect several biological parameters of the medfly (Krainacker et al., 1987 ), we reared all four populations for one generation under identical lab conditions and used the F1 progeny in our experiments. Rearing of wild flies was done by keeping adults in groups of about 100 individuals in wooden, wire-screened cages (30 × 30 × 30 cm) provided with water and a standard adult diet (YS) consisting of a mixture of yeast hydrolysate, sugar, and water at a 4:1:5 ratio. Females were allowed to oviposit into 5-cm hollow, red plastic hemispheres (domes) that were artificially punctured with 40–50 evenly distributed holes. Eggs were deposited on the inner surface of the dome. Each dome was fitted into a hole (5-cm in diameter) in the cover of a 5.5-cm plastic Petri dish. Water was placed in the Petri dish in order to maintain humidity levels beneath the dome to an adequate level for female oviposition (Boller, 1985 ). A plastic cup containing 0.5 ml of orange juice was also placed in the Petri dish to stimulate oviposition. Immatures were reared (same density of 50–100 eggs per food amount for all populations) on an artificial diet consisting of 200 g sugar, 200 g brewer’s yeast, 100 g soybean flour, 4 g salt mixture, 16 g ascorbic acid, 16 g citric acid, 3 g sodium propionate, and 1 l water (Boller, 1985 ).
