A study on fruit fly host range reveals the low infestation rate of Bactrocera dorsalis (Tephritidae) in Mayotte

1. The oriental fruit fly (Bactrocera dorsalis) is one of the world's most invasive and polyphagous fruit pests. It causes severe damage throughout its range and can devastate the entire fruit harvest in unprotected orchards. In 2007, B. dorsalis was detected in Mayotte, where it now ranks ninth on the list of fruit fly species of economic importance. This tropical island is a good study area to analyse the host range of B. dorsalis and its interactions with other resident fruit fly species. 2. Two field campaigns were carried out from 2012 to 2014 and from 2019 to 2021. We collected fruit from all over the island in cultivated and non-cultivated areas and compared the infestation rates between the two periods. 3. We detected six fruit fly species, including the common species Dacus ciliatus, Neoceratitis cyanescens, Ceratitis capitata, B. dorsalis and two rarer species, Dacus etiennellus and Trirhithrum nigerrimum. 4. The most surprising result was the low occurrence of B. dorsalis, with only seven host plant species identified out of a total of 84 plant species. Infestation rates were low for these host plant species, even in the case of mango (11.71 flies/kg) and Indian almond (0.97 fly/kg), which are considered to be major host plants of B. dorsalis. 5. Bactrocera dorsalis seems to have a lower impact in Mayotte than in other parts of the world. We discuss the possible causes of the weak infestation rates observed, which could provide the key to regulating the species on the island.