Managing Oriental fruit fly, Bactrocera dorsalis (Hendel): prioritising host plants using the host reproduction number

Abstract The number of adult fruit flies that can emerge from one kilogram of fruit is termed the Host Reproduction Number (HRN). HRN can be used to determine the level of host suitability, or the Host Suitability Index (HSI), is revolutionary because HRN makes assessment of incursion risk, risk of establishment or spread potential of tephritids easier. The HSI is a useful tool for managers to develop surveillance protocols or regulatory responses to fruit fly incursions associated with international horticultural trade. However, there is currently no comprehensive list of HRN and associated HSI classifications for Oriental fruit fly (OFF) Bactrocera dorsalis (Hendel). Oriental fruit fly is a tephritid fruit fly pest renowned globally for invasion success and crop destruction. In this study, we reviewed the OFF host suitability literature with the aim of providing a comprehensive list of categorised HRN data that could be used to inform fruit fly management decisions. In total, we found information on 613 B. dorsalis host plants. Of these, 138 had associated HRNs (22.5%) while 475 had no associated HRNs but were reported as host plants. Within the HRN group, the HSI classified these into 21 very good hosts, 66 good hosts, 39 moderately good hosts, 10 poor hosts, and 2 very poor hosts. There were 70 possible non hosts. We found that 20 plant species were in more than one HSI category. Surveillance measures and incursion management of OFF benefit from the incorporation of HRN values into existing policy. Currently, the usefulness of HRN values is limited by the large number of hosts (many of which are commercial) for which no associated HRN value is available. Also, the circumstances and geographic location in which HRN data was collected is missing. There would be great global benefit to OFF management programs if HRN could be determined and published in a consistent manner for a wider range of hosts and under a wider range of conditions.