Abstract
The Mediterranean fruit fly Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) is one of the most important pest of fruits and vegetables in tropical and subtropical countries. The sterile insect technique (SIT) as a component of area-wide integrated pest management (AW-IPM) approaches is being used for the successful management of this pest. VIENNA 8 is a genetic sexing strain (GSS) that has a white pupae (wp) and temperature sensitive lethal (tsl) mutation, the latter killing all female embryos when eggs are exposed to high temperatures (34°C). The use of this GSS permits production and the release of only males which has increased the cost effectiveness of the SIT several fold for this pest. An efficient method of identification of recaptured sterile males can further increase the cost effectiveness of the SIT for this pest. Therefore, VIENNA 8-Sergeant2 (Sr2) strain and the transgenic strain VIENNA 8–1260 having visible markers were constructed. All three strains were evaluated for egg production, egg hatch, and egg sterility parameters under semi mass-rearing conditions and mating competitiveness in field cages. VIENNA 8–1260 females produced significantly fewer eggs as compared with the two other strains, which produced similar numbers of eggs. However, egg hatch of all strains was similar. Egg hatch of eggs produced by untreated females that had mated with adult males that had been irradiated with 100 Gy as pupae 2 days before emergence, was different for the three strains, i.e., egg hatch of 0.63%, 0.77%, 0.89% for VIENNA 8, VIENNA 8–1260, and VIENNA 8-Sr2, respectively. Differences in male mating competitiveness of the three strains against wild-type males were gradually reduced with successive generations under semi mass-rearing conditions. However, VIENNA 8 males adapted faster to laboratory conditions as compared with VIENNA 8-Sr2 and VIENNA 8–1260 males with respect to mating competitiveness. VIENNA 8 males of the F10 generation were equally competitive with wild-type males, whereas the mating competitiveness of VIENNA 8-Sr2 and VIENNA 8–1260 males was similar but lower as compared with wild-type males. Males from all three strains copulated earlier than wild-type males. Results are discussed in relation with the potential benefits of incorporating novel strains for more effective SIT application.
Highlights
The Mediterranean fruit fly Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) is the most destructive fruit fly pest in the world, causing extensive damage to fruits and vegetables [1,2]
Two main factors have made the sterile insect technique (SIT) for the Mediterranean fruit fly more cost-effective, i.e. the first was the technological developments that enabled the production of the flies on a large scale and the second was the development of genetic sexing strains (GSS) that enabled male-only releases [9]
Eggs collected during the course of the 5 generations tested (3rd, 5th, 6th, 7th, 10th) revealed that the 3 strains had significantly different egg hatch rates in those combinations with non-irradiated males (F2,887 = 27.5, P < 0.001), i.e. the eggs produced by the VIENNA 8–1260 strain had a significantly lower hatch rate than the other 2 strains
Summary
The Mediterranean fruit fly Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) is the most destructive fruit fly pest in the world, causing extensive damage to fruits and vegetables [1,2]. Two main factors have made the SIT for the Mediterranean fruit fly more cost-effective, i.e. the first was the technological developments that enabled the production of the flies on a large scale and the second was the development of genetic sexing strains (GSS) that enabled male-only releases [9]. Testimony to this is the fact that the overwhelming majority of operational programmes against this pest in the world that have an SIT component are rearing the GSS of this species [10]. Damage to the fruit that occurs due to oviposition by sterile females and secondary infestations caused by microbes can be avoided [13]
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