The use of host reproduction number and host suitability index to rank hosts of fruit flies in Africa

Tephritid fruit flies are major economic pests for fruit production and are an impediment to trade. Different host fruits are known to vary in their capacity or suitability for fruit flies to complete their life cycle and this is particularly important for regional and local fruit fly management. The capacity of host fruit to support the full life cycle of fruit flies is measured by the number of adults produced from one kg of fruit. This metric is termed the Host Reproduction Number (HRN) and values range from zero for non-hosts to many hundreds for highly suitable hosts. Twenty-one published papers were reviewed to extract fly-host data. Here, the HRN was used to divide host status into six Host Suitability Index (HSI) categories. The HRN and HSI concept was applied to 21 host status papers covering 211 hosts and nine species of polyphagous fruit flies in Africa. Preferably, field infestation rate was used, rather than laboratory experiments. The HRN and HSI may be a useful concept in developing management strategies that recognise varying host status, for determining surveillance and detection protocols for potential incursions, and to guide the appropriate regulatory response during endemic fruit fly outbreaks and exotic incursions. HRN and HSI could be used for exports and imports and the associated levels of risk mitigation.