• To measure trapping success, it would be useful to correlate damage reduction with the reduction of the fruit fly population. It is recommended that additional traps be set up for monitoring purposes. Monitoring traps can be placed every 5-6 ha inside the farm area as well as at border areas surrounding the fruit orchard. Fruit-fly populations are monitored weekly in order to calculate the number of flies trapped per day (FTD): 39 FTD = Total No. fruit flies collected in traps x No. days No. traps • Total No. fruit flies trapped/No. traps x No. days. An area can be considered free of the pest if the FTD is 0. An FTD between 0.1 and 1 means that the population is suppressed, while an FTD >1 warrants for continued control efforts. The success of fruit fly control can be further determined by observing the percentage of fruits that are infested. Fruit samples are taken randomly and placed individually in ‘rearing’ boxes (room temperature) to check whether or not fruit flies will emerge after about two weeks. The number of infested samples versus the total number of samples indicates the proportion of infestation. • Food lure (protein bait): Protein bait is applied as spot spraying on 3-4 spots per tree. About 25 ml of bait is sprayed on each spot. Fruits should not come in contact with the bait, which can reduce their quality due to stains. The average dosage for a protein bait application is 1 litre/ha. In practice, protein bait can be mixed with selected insecticides (e.g. malathion, fipronil), which would classify this approach as a ‘lure and kill’ system. Applications are carried out during the morning hours (e.g. 08.00 to 10.00) and usually start at the beginning of fruit formation once about 75% of the trees on the farm have reached this stage. They are continued on a weekly basis until harvesting time. It is estimated that about 18-20 applications are needed in a growing season, depending on the type of fruit. Protein bait can also be applied as a mass trapping tool, in combination with ME block. Because protein bait attracts females while ME attracts males, the number of ME blocks can be reduced to 7-9 units per ha. 3.3.2 Conclusions: development of BCA in fruit production The correct identification of fruit fly species is crucial to design proper strategies for control. Current control methods include cultural practices, use of attractants for mass trapping and attract and kill systems, fruit bagging, sanitation, the potential use of natural enemies and other biocontrol agents. An important requirement for success is an area-wide control approach covering areas larger than just a single fruit orchard. Additionally, locations outside the fruit growing area should be considered as potential sources for fruit fly and checked accordingly. Applications of control techniques should be done simultaneously throughout the target areas. This also requires that farmers cooperate and are properly informed about the advantages of a community (area-wide) approach. Successful fruit fly control can be maintained over many years, but only after the awareness of farmers and others living in the target area has been increased to a level that results in effective cooperation.
Implementing Biological Control Agents in the ASEAN Region
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