Rearing technology and taxonomy of the Cape fly Ceratitis quilicii

The objectives of this project are to develop a larval diet and rearing protocol for Ceratitis quilicii (Cape fly) and identification tools using an APP for economically-significant fruit fly pests in South Africa and easier methods for larval identification.

1. Larval diet development and rearing protocol: Various diet ingredients will be investigated, namely sources of protein/sugar and their ratios, as well as additives, such as carrot/fruit juices and preservatives (e.g. nipagin) which were found to be successful in rearing of flies.  Both liquid and solid diets will be evaluated.  Different egg laying devices will also be tested, as well as different environmental conditions (humidity, temperature and daylength).
2. Identification tools: This objective will focus on developing easy-to-use identification APPs and will be done in collaboration with international partners at the RMCA.  The focus of the morphological identification will be the mouth hooks, which are the only ‘hard’ structure on the larval body.

The results obtained during this study point to developmental variations in flies reared from differing larval nutritional protein content, where in this case the 8% protein larval diet treatment performed the best overall. The 8% protein larval diet treatment produced larger flies and flies with the smallest wings, which could lead to better dispersal due to higher wing loading. An APP was developed for the identification of fruit fly larvae, and is now freely available.

Therefore, the findings of the current study can be used to gain a better understanding of the influence from larval nutrition on certain parameters of adult fruit flies and can help to improve the composition of larval diets to rear this species on a larger scale in laboratories for research purposes. The identification APP for fruit fly larvae is suitable only for users with some experience of dissection and taking of morphometric measurements, but ongoing improvements will take place to update the APP to make it more user-friendly.

A suitable diet with 8% protein content is recommended and was found to produce a fly with the best physiological and morphological characteristics. This can be used to incorporate into the mass rearing protocol of various projects and insectaries.  Larval identification of fruit flies is not easy, and should currently only be conducted by people with some expertise.  Although not that user-friendly, it is still the first tool to be developed (worldwide) for fruit fly larvae, and is now freely available.