|Thursday, 31 January 2013 15:09|
Quarantine surveillance encompasses activities that assist in the early detection of unwanted exotic fruit flies and other pests and diseases. It is not restricted to trapping systems alone. It includes border inspections, passenger profiling, profiling of airline and shipping routes with respect to level of risk, assessments of contents of quarantine bins, trapping, host fruit surveys and public and government awareness.
Quarantine surveillance is designed as an early warning system so that authorities are able to mobilize resources quickly to deal with an incursion or establishment of an unwanted pest species, before the introduced species becomes widely distributed.
Having an effective quarantine surveillance system in place gives importing countries confidence in data on the presence (or absence) and economic importance of fruit fly species that already exist in each country. Quarantine surveillance is a prerequisite for developing quarantine protocols for overseas trade in fresh fruits and vegetables. No quarantine surveillance = no trade in fresh fruits.
Trapping provides information that is an essential starting point for understanding and managing fruit fly populations. The type of information generated includes: the species of fruit flies present, geographic distributions on a regional and national basis, seasonal abundance, population density differences in different habitats (e.g. rainforest vs. village), abundance of fruit flies during fruiting periods, impact of control or eradication measures on fruit fly populations and, most critically, early detection of incursions and establishment of exotic species.
Numerous trap types have been designed and tested, with many being discarded. In the Pacific region, the commonly used model is the modified Steiner trap. It is an horizontal plastic cylinder with an opening at each end. The lure is added by suspending, from the centre of the trap, a cotton wick soaked in 2-3 ml of a mixture of a chemical lure and an insecticide, usually malathion or dichlorvos.
Modified Steiner trap for fruit fly monitoring (Photo: N.Waqa)
Various chemical lures may be used to attract flies to traps, but the most effective are male lures. Of the different male lures available, two are commonly used for trapping in the Pacific region: Cue-lure and methyl eugenol. Most fruit fly species in the Pacific region are attracted to one of the lures, but some species are not attracted to male lures at all. Lure attraction and distribution of pest species in the Pacific region are summarized below:
The species that do not respond to male lures may be sampled only by host fruit surveys and protein bait spraying. Major pests that do not respond to male lures to be kept outside the Pacific region, besides the above-mentioned species, include cucumber fruit fly (Bactrocera cucumis (French)), a pest of cucurbits, tomato and papaya in Australia, and Solanum fruit fly, (B. latifrons (Hendel)), a pest of tomato, eggplant, capsicum and chilli in Asia and Hawaii.
Two traps (one baited with Cue-lure and one with methyl eugenol) are usually set at each trapping site. Sites are selected to cover high risk areas such as international ports and airports, urban and suburban areas, tourist resorts, refuse dumps, near diplomatic missions, and education institutes that cater for overseas students, to detect rapidly foreign species that may be introduced through contaminated exotic fruits brought in by travelers. Some countries (Fiji Islands, Tonga, New Caledonia) also use traps baited with trimedlure, which attracts Mediterranean fruit fly (Ceratitis capitata), a species found in Hawaii and western Australia.
Traps are emptied weekly to monthly, and collected flies are placed inside small cardboard boxes for later examination.