Evaluation of Rearing Parameters of a Self-Limiting Strain of the Mediterranean Fruit Fly, Ceratitis capitata (Diptera: Tephritidae)

Abstract

Simple SummaryThe Mediterranean fruit fly (medfly), Ceratitis capitata, causes billions of dollars in losses to a wide variety of fruit and vegetable crops. Therefore, it needs to be effectively controlled. The use of chemical control is not sustainable because of its negative effects on the environment. As an alternative, the use of an area-wide sterile insect technique (SIT) has been shown to be a cost-effective and environmentally friendly option. This technique involves the mass rearing, irradiation for sterility, and release of males. Matings between wild females and sterile males result in no offspring production. The genetically sterile female specific medfly strain OX3864A has the potential to reduce the population of medfly through periodic male releases in a process similar to the common SIT. This study looked at ways of optimizing the mass rearing of the OX3864A strain. We found that the highest egg production is reached when mass-rearing cages are populated with pupal densities ranging from 14,000 to 18,000 per cage. In parallel, the optimal embryo densities for strain propagation and male-only pupal production are recommended. Using these densities, the quality of the insects meets the common standards.The Mediterranean fruit fly (medfly), Ceratitis capitata, is a significant pest of stone and pome fruit that causes considerable economic losses worldwide. Current control is primarily based on insecticides, which are often mixed with protein baits. Oxitec has developed a self-limiting medfly strain (OX3864A) that demonstrates conditional female-specific mortality in the early life stages. Sustained release of OX3864A males offers medfly control, which should lead to substantial economic benefits in area-wide programmes. In the current study, the optimum quantities of mature and immature stages of the strain are assessed under semi-mass production. Moreover, the rearing and quality control limitations related to the production of this strain are provided. The data here demonstrate that the egg hatch rate can reach >85% under optimum rearing conditions. However, this depends on the number of pupae loaded in a cage and their ages. The suggested pupal density ranges between 14,000 and 18,000 pupae per cage to provide optimum egg production. In parallel, the embryo densities of 1.25–1.5 mL/kg larval Tet+ diet are recommended for strain propagation, while embryo densities of 1.25–2.0 mL/kg larval Tet− diet are suggested for male-only pupal production.