Occurrence and phenology of fruit flies (Ceratitis capitata and C. rosa) on host plants in the Western Cape

The objectives of this trial were to identify, map and determine phenology of alternate host plants and fruit flies, determine species composition in infested alternate hosts and to identify potential bio-control agents for fruit flies.

In the Groenland area, 93% of the flies emerging from fruits were Medflies, and only 7% were natal flies.  In the Stellenbosch area, both fly species seemed to have a number of bridging hosts throughout the year, with natal fly comprising 57% of the emerged flies, and Medfly comprising the remaining 43%.

Good hosts include jambos, Natal plum, mango, tree tomato and pepperdews, while  relatively low numbers of flies (<10) emerged from quince, peach, wine grapes, naartjies, apples, blackberries, guava and plum.  Alternate hosts such as loquats, guavas, oranges and early peaches are particularly instrumental in sustaining winter populations of flies in both areas.

Home gardens are indeed a threat to good fruit fly management programmes, as these yield exceptionally high numbers of flies relative to orchards for most months of the year.  The importance of good sanitation practices and encouraging home owners to adopt these too, cannot be overemphasized.  This project was part of a Masters thesis, which was supervised by the project leader and co-supervised by Dr Aruna Manrakhan.  We are in the process of developing an information pamphlet/CD from this data, which should assist producers and home owners in achieving good fruit fly management.