Fruit fly: a major threat to New Zealand’s fruit and vegetable industries?
By: Dr Ram SriRamaratnam
Introduction
On 2 May 1996, Mediterranean fruit fly (Ceratitis capitata) was identified in the Mt Roskill suburb in central Auckland, with the trapping of two male flies. By 23 May 1996, this number had increased to 41 adults (31 males and 10 immature females) and 85 larvae extracted from twelve infested fruits (eight feijoas, two tangelos and two grapefruits). The initial find and its identification constituted a fruit fly incursion. In response to the trap captures, an A-zone (200 m radius) and a B-zone (1.5 km radius) around the finds were defined, in which further monitoring and necessary control measures have been undertaken.
The latest fruit fly find was the third in 1996, up to the end of May, and all of them were in urban Auckland. The previous finds were the papaya fruit fly (Bactrocera papayae) and the Queensland fruit fly (Bactrocera tryoni). The finds have all been within home gardens in urban Auckland. The control measures adopted by MAF in response to these recent incursions have been exhaustive, with no finds outside the A-zone.
Fruit flies belong to the family Tephritidae, which includes over 4,500 species. About 20 species can be considered as serious pests, even though 60 species are known to infest commercial fruit types. Some of the well-known species are the Queensland, Oriental, Mediterranean, Caribbean and papaya fruit flies. These fruit flies have a wide range of hosts; Queensland fruit fly is one of the most potent pests in that it infests more than 100 species of fruits. Mediterranean fruit fly is very similar, but is able to thrive better in drier conditions than Queensland fruit fly.
This article uses the recent incursion of Mediterranean fruit fly as a benchmark to consider the threat posed to New Zealand’s fruit and vegetable industries by the fruit fly pest. In order to carry out this task, the life cycle, the host preferences and the current worldwide distribution of this species of fruit fly are considered. The level of importance of the fruit and vegetable industries in terms of their export values and the levels of direct employment is also analysed, along with their regional production distribution in New Zealand.
Important features of New Zealand’s agricultural security system related to fruit fly, which is under the purview of MAF, are covered subsequently. This system consists of border protection measures, monitoring/surveillance systems and control/eradication mechanisms. This is followed by a description of control measures adopted in New Zealand and some other countries in response to fruit fly incursions. The nature of responses by important trading partners to the recent incursion is outlined next. Finally, certain aspects of potential future incursions such as location, timing, type of fruit fly and the phytosanitary (plant health) responses of trading partners are considered. These are used to provide an overall perspective on the scope of the economic impacts of a fruit fly outbreak in terms of trade losses, control costs and regional employment in New Zealand.
Contact for Enquiries
Manager, Strategic Science Team
MAF Biosecurity New Zealand
PO Box 2526
Wellington
NEW ZEALAND
Phone: +64 4 894 0115
Fax: +64 4 894 0731
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